Rule2026-02350
Air Plan Revisions; California; Heavy-Duty Vehicle Inspection and Maintenance Program
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
February 6, 2026
Effective
March 9, 2026
Issuing agencies
Environmental Protection Agency
Abstract
The U.S. Environmental Protection Agency (EPA) is taking final action to partially approve and partially disapprove a submission by the State of California to revise its State Implementation Plan (SIP) relating to the control of emissions from non-gasoline combustion vehicles over 14,000 pounds. The EPA's partial approval will allow the submitted Heavy-Duty Inspection and Maintenance Regulation ("HD I/M Regulation") to become federally enforceable as part of the California SIP with respect to vehicles registered within the State. The EPA is partially disapproving the submission to the extent that the HD I/M Regulation purports to apply to out-of-state vehicles as inconsistent with the Clean Air Act (CAA), because the State has not provided adequate assurances under CAA section 110(a)(2)(E)(i) that implementation of the SIP is not prohibited by Federal law. The partial disapproval will not trigger CAA section 179 sanctions because the submittal is not a required submission under CAA section 110(a)(2).
Full Text
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<title>Federal Register, Volume 91 Issue 25 (Friday, February 6, 2026)</title>
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[Federal Register Volume 91, Number 25 (Friday, February 6, 2026)]
[Rules and Regulations]
[Pages 5325-5351]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-02350]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R09-OAR-2025-0061; FRL-12606-02-R9]
Air Plan Revisions; California; Heavy-Duty Vehicle Inspection and
Maintenance Program
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: The U.S. Environmental Protection Agency (EPA) is taking final
action to partially approve and partially disapprove a submission by
the State of California to revise its State Implementation Plan (SIP)
relating to the control of emissions from non-gasoline combustion
vehicles over 14,000 pounds. The EPA's partial approval will allow the
submitted Heavy-Duty Inspection and Maintenance Regulation (``HD I/M
Regulation'') to become federally enforceable as part of the California
SIP with respect to vehicles registered within the State. The EPA is
partially disapproving the submission to the extent that the HD I/M
Regulation purports to apply to out-of-state vehicles as inconsistent
with the Clean Air Act (CAA), because the State has not provided
adequate assurances under CAA section 110(a)(2)(E)(i) that
implementation of the SIP is not prohibited by Federal law. The partial
disapproval will not trigger CAA section 179 sanctions because the
submittal is not a required submission under CAA section 110(a)(2).
DATES: This rule is effective March 9, 2026.
ADDRESSES: The EPA has established a docket for this action under
Docket ID No. EPA-R09-OAR-2025-0061. All documents in the docket are
listed on the <a href="https://www.regulations.gov">https://www.regulations.gov</a> website. Although listed in
the index, some information is not publicly available, e.g.,
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Certain other material, such as
copyrighted material, is not placed on the internet and will be
publicly available only in hard copy form. Publicly available docket
materials are available through <a href="https://www.regulations.gov">https://www.regulations.gov</a>, or please
contact the person identified in the FOR FURTHER INFORMATION CONTACT
section for additional availability information. If you need assistance
in a language other than English or if you are a person with a
disability who needs a reasonable accommodation at no cost to you,
please contact the person identified in the FOR FURTHER INFORMATION
CONTACT section.
FOR FURTHER INFORMATION CONTACT: Doris Lo, EPA Region IX, 75 Hawthorne
St., San Francisco, CA 94105; telephone number: (415) 972-3959; email
address: <a href="/cdn-cgi/l/email-protection#fe9291d09a918c978dbe9b8e9fd0999188"><span class="__cf_email__" data-cfemail="1e7271307a716c776d5e7b6e7f30797168">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION: Throughout this document, the use of
``Agency,'' ``we,'' ``us,'' or ``our'' refers to the EPA. We use
multiple acronyms and terms in this preamble. While this list may not
be exhaustive, to ease the reading of this preamble and for reference
purposes, the EPA defines the following terms and acronyms here:
ACT--Advanced Clean Trucks
ATA--American Trucking Associations
CAA--Clean Air Act
CAELP--Center for Applied Environmental Law and Policy,
Environmental Defense Fund, and Natural Resources Defense Council
CARB--California Air Resources Board
CBI--Confidential Business Information
CCA--Coalition for Clean Air
CCAEJ--Center for Community Action and Environmental Justice and
Sierra Club
CCR--California Code of Regulations
CFR--Code of Federal Regulations
CRA--Congressional Review Act
CTA--California Trucking Association
EPA--Environmental Protection Agency
FIP--Federal Implementation Plan
FSOR--Final Statement of Reasons
GVWR--Gross Vehicle Weight Rating
HD I/M--Heavy-Duty Inspection and Maintenance
HDVIP--Heavy-Duty Vehicle Inspection Program
ISOR--Initial Statement of Reasons
MECA--Manufacturers of Emission Controls Association
NTTAA--National Technology Transfer and Advancement Act
NTTC--National Tank Truck Carriers
OBD Standards--California Standards for Heavy-Duty Remote On-Board
Diagnostic Devices
OMB--Office of Management and Budget
OOIDA--Owner-Operator Independent Drivers Association
PRA--Paperwork Reduction Act
PSIP--Periodic Smoke Inspection Program
RFA--Regulatory Flexibility Act
RFP--Reasonable Further Progress
SCAQMD--South Coast Air Quality Management District
SIP--State Implementation Plan
TRALA--Truck Rental and Leasing Association
UCS--Union of Concerned Scientists
UMRA--Unfunded Mandates Reform Act
U.S.C.--United States Code
USMCA--United States-Mexico-Canada Agreement
Table of Contents
I. Background
A. CAA Requirements
B. What regulations did the State submit?
C. What is the purpose of the submitted regulations?
D. What did the EPA propose?
II. The EPA's Evaluation and Final Action
III. Response to Public Comments and Discussion
A. Comments in Support of Partial Disapproval
B. Comments in Support of Full Approval
C. Other Comments
IV. Incorporation by Reference
V. Statutory and Executive Order Reviews
I. Background
A. CAA Requirements
Under the CAA, the EPA establishes national ambient air quality
standards (NAAQS) to protect public health and welfare. The EPA has
established NAAQS for certain pervasive air pollutants including ozone,
carbon monoxide, nitrogen dioxide, sulfur dioxide, lead, and
particulate matter. Under CAA section 110(a)(1), States must submit
plans that provide for the implementation, maintenance, and enforcement
of the NAAQS within each State. Such plans are referred to as SIPs, and
revisions to those plans are referred to as ``SIP revisions.'' CAA
section 110(a)(2) sets forth the content requirements for SIPs. Among
the various requirements, SIPs must include enforceable emissions
limitations and other control measures, means, or techniques as may be
necessary or appropriate to meet the applicable requirements of the
CAA.\1\ SIP revisions may be submitted to address specific CAA
requirements (such as the elements
[[Page 5326]]
and demonstrations required within an attainment plan), or, as with the
State submittal addressed in this action, may be provided to
demonstrate emissions reductions to support attainment.
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\1\ See CAA section 110(a)(2)(A).
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Upon receiving a SIP that meets the completeness criteria in CAA
section 110(k)(1)(A), the EPA must determine whether the submission
meets all applicable CAA requirements.\2\ The EPA must either approve,
conditionally approve, approve in part and disapprove in part, or
disapprove a complete State submission within twelve months.\3\ In
addition to the limitations described above, CAA section 110(a)(2)(E)
provides that a SIP must include ``necessary assurances'' that the
State ``is not prohibited by any Federal or State law from carrying out
such implementation plan or portion thereof'' and that the State or
applicable State entity has adequate authority, personnel, and funding
to carry out adequate implementation of the SIP.
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\2\ See CAA section 110(k)(3).
\3\ Id.; CAA section 110(k)(4).
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Under California law, the California Air Resources Board (CARB) is
the State agency responsible for adopting and submitting SIP revisions
to the EPA for review. These include both local rules adopted by county
and regional air districts (typically regulating stationary source
emissions) and statewide regulations adopted by CARB and other State
agencies. If approved into the SIP, submitted regulations become
federally enforceable pursuant to CAA section 110(a)(2)(A).
B. What regulations did the State submit?
CARB submitted the ``Heavy-Duty Inspection and Maintenance
Regulation'' \4\ (``HD I/M Regulation'') as a revision to the
California SIP on December 14, 2022.\5\ Table 1 identifies the
regulatory sections included in the HD I/M Regulation and addressed by
this action with the dates that they were adopted by CARB and submitted
to the EPA.
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\4\ The State of California more commonly refers to the HD I/M
Regulation as the ``Clean Truck Check.'' See, e.g., CARB, Clean
Truck Check (HD I/M), <a href="https://ww2.arb.ca.gov/our-work/programs/CTC">https://ww2.arb.ca.gov/our-work/programs/CTC</a>
(last visited January 26, 2026).
\5\ Letter (with enclosures) dated December 7, 2022, from Steven
S. Cliff, Ph.D., Executive Officer, CARB, to Martha Guzman, Regional
Administrator, EPA Region IX (submitted electronically December 14,
2022). The letter and enclosures, which include the HD I/M
Regulation, among other materials, are included in the docket for
this rulemaking.
Table 1--Submitted Regulations
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Relevant sections of
Agency Regulation title California Code of Adopted Submitted
Regulations (CCR)
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CARB............................. Heavy-Duty Vehicle Amended section: 13 CCR 12/09/2021 12/14/2022
Inspection and 2193; New sections: 13
Maintenance CCR 2195, 2195.1, 2196,
Program. 2196.1, 2196.2, 2196.3,
2196.4, 2196.5, 2196.6,
2196.7, 2196.8, 2197,
2197.1, 2197.2, 2197.3,
2198, 2198.1, 2198.2,
2199, and 2199.1.
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The HD I/M Regulation incorporates by reference the ``California
Standards for Heavy-Duty Remote On-Board Diagnostic Devices'' (``OBD
Standards''). CARB approved the HD I/M Regulation on December 9, 2021,
through Resolution 21-29. Following minor, non-substantive edits by
CARB staff,\6\ CARB formally adopted the final HD I/M Regulation and
OBD Standards on August 22, 2022, through CARB Executive Order R-22-
002. For more information on the HD I/M Regulation, including the EPA's
prior actions on precursor SIP submittals, see section II of the
preamble to the proposed action.\7\
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\6\ CARB, Addendum to the Final Statement of Reasons for
Rulemaking, ``Public Hearing to Consider Proposed Heavy-Duty
Inspection and Maintenance Regulation'' (October 4, 2022).
\7\ 90 FR 41525, 41528 (August 26, 2025).
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C. What is the purpose of the submitted regulations?
Based on ambient data collected at numerous sites throughout the
State, the EPA designated certain areas within California as
nonattainment for the ozone NAAQS and the particulate matter (PM)
NAAQS, which includes both coarse and fine particulate matter (i.e.,
PM<INF>10</INF> and PM<INF>2.5</INF>).\8\ The EPA redesignated to
attainment several areas in California previously designated as
nonattainment for the carbon monoxide NAAQS because these areas
attained the standard and are subject to an approved maintenance plan
demonstrating how the State will maintain the carbon monoxide standard
into the future.
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\8\ See generally 40 CFR 81.305.
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Mobile source emissions constitute a large portion of overall
emissions of ozone precursors, including volatile organic compounds
(VOC) and oxides of nitrogen (NO<INF>X</INF>), as well as direct PM and
PM precursors, including NO<INF>X</INF>, sulfur dioxide
(SO<INF>2</INF>), and carbon monoxide in the various air quality
planning areas within California.\9\ According to CARB, heavy-duty
vehicles constitute 52 percent of the on-road NO<INF>X</INF> emissions
and 54 percent of on-road PM<INF>2.5</INF> emissions.\10\ In addition,
according to CARB, out-of-state or out-of-country heavy-duty vehicles
constitute approximately half of the total number of heavy-duty
vehicles travelling in the State and approximately 30 percent of heavy-
duty vehicle NO<INF>X</INF> emissions.\11\ According to CARB, the HD I/
M Regulation is intended to reduce PM<INF>2.5</INF> and NO<INF>X</INF>
emissions from heavy-duty non-gasoline combustion vehicles operating in
California to further ozone and PM attainment by areas within the
State.\12\
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\9\ VOC and NO<INF>X</INF> are precursors responsible for the
formation of ozone, and NO<INF>X</INF> and SO<INF>2</INF> are
precursors for PM<INF>2.5</INF>. SO<INF>2</INF> belongs to a family
of compounds referred to as sulfur oxides. PM<INF>2.5</INF>
precursors also include VOC and ammonia. See 40 CFR 51.1000.
\10\ See ``Public Hearing to Consider the Proposed Heavy-Duty
Inspection and Maintenance Regulation--Staff Report: Initial
Statement of Reasons,'' October 8, 2021, at I-2 (``Staff Report'').
\11\ Id. at II-2.
\12\ Id. at II-1.
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The HD I/M Regulation establishes a comprehensive I/M program for
heavy-duty vehicles that is intended to ensure that vehicle emissions
control systems on these vehicles are operating as designed and
repaired quickly. CARB asserted that this regulatory revision builds on
CARB's current heavy-duty inspection programs, including building on
and replacing the Heavy-Duty Vehicle Inspection Program and Periodic
Smoke Inspection regulations for heavy-duty vehicles.\13\
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\13\ 13 CCR 2180 through 2189. These programs are sunset under
13 CCR 2199.1, which is included in the HD I/M Regulation SIP
submittal.
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The HD I/M Regulation applies to all non-gasoline combustion
vehicles above 14,000 gross vehicle weight rating (GVWR) that operate
in California. Unlike virtually all prior CARB regulations and similar
regulations adopted by other States, the HD I/M Regulation would also
apply to vehicles registered out-of-state and out-of-country that
operate within the State of
[[Page 5327]]
California for almost any length of time.\14\ Some vehicle categories
are exempted, including zero-emission vehicles (i.e., electric
vehicles), emergency and military tactical vehicles, and other classes
defined by use or purpose. There is a limited 5-day pass-through
exception permitting program which contemplates that a ``vehicle owner
may obtain written approval from the Executive Officer to operate a
vehicle for up to five consecutive calendar days without being subject
to'' 13 CCR 2196.1(a)(1) and (2), which govern the owner operator
requirements.\15\ The 5-day exemption is available once per calendar
year to vehicles with no outstanding enforcement actions. The five days
must run consecutively after approval and the application must be sent
at least seven business days ``prior to the vehicle's planned travel or
entry in California.'' \16\ Vehicle owners must request the exemption
in advance through CARB's compliance platform by providing a variety of
information, including the vehicle's registration information, vehicle
identification number (VIN), relevant dates, and origin and destination
information. If granted, the owner must keep the pass document in the
vehicle and provide it to CARB inspectors upon request.
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\14\ The HD I/M Regulation permits entities subject to the rule
to apply once per calendar year for a 5-day ``pass through''
exception which must be granted in each instance and on an
individualized basis. The EPA notes that California has not provided
assurances that this additional compliance step meaningfully changes
the coverage of the HD I/M Regulation.
\15\ 13 CCR 2196(d).
\16\ 13 CCR 2196(d)(1).
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The HD I/M Regulation requires owners of heavy-duty vehicles
operating in California (including out-of-state and out-of-country
vehicles) to report owner and vehicle information to CARB. It also
requires owners of heavy-duty vehicles to demonstrate that their
vehicle emissions control systems are properly functioning through
vehicle compliance tests completed by CARB-approved testers and to
periodically submit vehicle compliance test results to CARB. Vehicles
equipped with on-board diagnostic (OBD) systems can be tested using OBD
data, while older non-OBD vehicles are subject to smoke opacity and
visual inspections. Vehicle owners are also required to have a valid HD
I/M compliance certificate with the vehicle while operating in
California, which they must present to a CARB inspector and/or
California Highway Patrol officer upon request.
The HD I/M Regulation also establishes a referee testing network to
provide independent evaluations of heavy-duty vehicles and services for
vehicles with inspection incompatibilities or compliance issues.
Finally, the HD I/M Regulation describes procedures for HD I/M roadside
inspections, including roadside monitoring and field inspections.
D. What did the EPA propose?
On August 26, 2025, the EPA proposed to partially approve and
partially disapprove, or, in the alternative, to fully approve, the HD
I/M Regulation into the California SIP.\17\ While the Agency proposed
to find that the submission generally meets applicable requirements of
the CAA and implementing regulations, the EPA proposed to partially
disapprove because of substantial concerns with allowing provisions in
the HD I/M Regulation that purport to regulate vehicles registered out-
of-state and out-of-country to become federally enforceable.
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\17\ 90 FR 41525, 41527-29.
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Specifically, the EPA proposed that California had not provided
necessary assurances that the State is not prohibited by any provision
of Federal or State law from implementing the SIP, as required by CAA
section 110(a)(2)(E)(i). The Agency proposed that the Commerce Clause
of the U.S. Constitution appears to prohibit implementing the HD I/M
Regulation because its extraterritorial reach burdens core
instrumentalities of interstate commerce, that is, heavy-duty vehicles
used in interstate shipping. The Agency noted that the HD I/M
Regulation effectively outsources the costs of emissions reductions
within California to other States and regulated entities in those
States by requiring compliance with California's inspection and
maintenance (``I/M'') regime even when the vehicles are not within
California. The Agency also noted that under the structure of CAA
section 110, a full approval of the HD I/M Regulation would effectively
force regulated entities in other States to comply with California's HD
I/M requirements, rather than the applicable requirements in their
respective States, including requirements approved by the EPA pursuant
to the CAA. Finally, we proposed that the extraterritorial reach of the
HD I/M Regulation appears to abrogate the foreign relation powers
vested exclusively in the Federal Government by the U.S. Constitution.
The EPA further proposed that the extraterritorial reach of the HD
I/M Regulation is inconsistent with CAA section 110. The Agency
observed that CAA section 110 requires the submission of SIPs by each
State and that full approval of the submission would, by making the HD
I/M Regulation federally enforceable, potentially result in multiple
conflicting sources of obligations. The Agency also noted that the HD
I/M Regulation was unusual in this respect and requested comment on all
aspects of the proposal, including whether a full approval of the
State's submission would raise additional concerns under any other
Federal or State law.
II. The EPA's Evaluation and Final Action
After reviewing California's submission and all comments received
during the public comment period, the EPA is finalizing a partial
approval and partial disapproval that will allow the HD I/M Regulation
to go into effect for CAA purposes except to the extent it applies to
vehicles registered outside the State. As previously noted, the CAA
expressly requires that a SIP submittal ``shall'' provide ``necessary
assurances'' that the State ``is not prohibited by any provision of
Federal or State law from carrying out such implementation plan or
portion thereof.'' \18\ The EPA cannot approve a SIP submission,
thereby making it effective for CAA purposes and federally enforceable,
unless ``it meets all of the applicable requirements of this chapter.''
\19\
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\18\ CAA section 110(a)(2)(E)(i).
\19\ CAA section 110(k)(3); see, e.g., Safe Air for Everyone v.
EPA, 488 F.3d 1088, 1093 (9th Cir. 2007) (``Before a SIP becomes
effective, EPA must determine that it meets the CAA's
requirements.'').
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The EPA determines that California has not provided necessary
assurances that the State is not prohibited by Federal law--
specifically, the Clean Air Act and the Commerce Clause of the U.S.
Constitution--from implementing the HD I/M Regulation to the extent it
purports to regulate vehicles registered out-of-state or out-of-country
based solely on whether such vehicles traverse California for virtually
any length of time. As discussed at proposal and reinforced by several
commenters, the State's submission externalizes the cost of additional
emissions reductions (out-of-state vehicles that must comply with
California's I/M regime on an ongoing basis) to achieve localized
benefits (additional emissions reductions that assist California in
demonstrating attainment of the NAAQS for the benefit of California
residents).
The Supreme Court has explained that the ``dormant'' Commerce
Clause prohibits ``even nondiscriminatory burdens on commerce'' when
``those
[[Page 5328]]
burdens clearly outweigh the benefits of a state or local practice.''
Nat'l Pork Producers Council v. Ross, 598 U.S. 356, 392 (2023)
(Roberts, C.J., concurring in part and dissenting in part).\20\ Such
burdens are of particular concern when they impose costs on interstate
trade, see, e.g., Kassel v. Consol. Freightways Corp., 450 U.S. 662,
674 (1981) (plurality op.); Raymond Motor Transp., Inc. v. Rice, 434
U.S. 429, 445 & n.21 (1978), where ``the nature of'' the market means
that a State regulation generates costs whether or not participants
sell into the regulating State, Nat'l Pork Producers, 598 U.S. at 400
(Roberts, C.J., concurring in part and dissenting in part), and where a
State regulation targets ``instrumentalities of interstate
transportation--trucks, trains, and the like,'' id. at 379-80 & n.2
(majority op.); accord id. at 392 (Sotomayor, J., concurring in part).
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\20\ As explained at proposal, a majority of the Court in
National Pork Producers affirmatively retained the balancing test in
Pike v. Bruce Church, Inc., 397 U.S. 137 (1970), for assessing the
validity of State regulations against the ``dormant'' aspect of the
Commerce Clause. 90 FR 41525, 41528 & n.22.
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In this context, Congress has exercised its exclusive regulatory
authority over interstate commerce by enacting CAA section 110 and
related provisions specifying States' obligations to attain the NAAQS.
Under CAA section 110, ``each State'' must develop and submit a plan
for implementing, maintaining, and enforcing the NAAQS ``within such
State.'' \21\ As a general matter, the Clean Air Act assigns national
regulation, including the regulation of interstate air pollution and
standards-setting for mobile sources, to the EPA. For example, title II
of the Act authorizes the EPA to set mobile source standards when
certain conditions are met and expressly preempts the adoption or
attempted enforcement of State standards (including certification,
inspection, and approval requirements for sale, titling, or
registration) except through the preemption waiver and waiver adoption
processes in CAA sections 177 and 209.\22\ Similarly, the Act generally
does not permit States to outsource the costs of emissions reductions
within their borders onto other States except where expressly
authorized.\23\ Under CAA section 110(a)(2)(D)(i)(I), for example,
States must submit plans to restrict certain emissions within their
borders if such emissions contribute significantly to nonattainment in
other States.
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\21\ CAA section 110(a)(1), (2) (emphases added).
\22\ See CAA sections 209(a) (preempting the implementation or
enforcement of vehicle and engine emission standards, including
certification, inspection, and other approval requirements), 209(b)
(setting out the process for requesting and issuing a preemption
waiver), and 177 (authorizing States to elect to implement standards
for which a preemption waiver has been granted under certain
conditions). Notably, the title II preemption provision includes a
savings clause authorizing State regulation of ``the use, operation,
or movement of registered or licensed motor vehicles,'' suggesting a
recognition that State regulatory authority is linked to vehicles
registered or licensed by the regulating State. CAA section 209(d)
(emphasis added).
\23\ See generally 13 CCR 2196; see also Comment ID EPA-R09-OAR-
2025-0061-0047 (demonstrating how referee locations are ``only found
in California'' and therefore inequitably discriminate against out-
of-state residents in both costs imposed and the burdens in seeking
to comply).
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Here, California's SIP submission seeks to remedy local
nonattainment by extending the State's regulatory reach to vehicles
registered in other States, and even other countries, that happen to
traverse the State. As explained at proposal and confirmed in this
final action, out-of-state vehicle owners and operators effectively
must comply with the HD I/M Regulation given the volume of interstate
trucking that passes through California, the uncertainties regarding
whether and when a route will cross through California over the course
of a year, and the significant penalties associated with failure to
comply. This result is not contemplated or authorized by CAA section
110, which requires ``each State'' to implement the NAAQS ``within such
State,'' and does not fall within any of the exceptional provisions of
the Act that contemplate one State reaching into another State in
pursuit of air quality improvements within its own borders. This is not
a lawful use of the CAA's SIP provisions, which instruct each State to
adopt appropriate controls for that State and prohibit the approval of
SIPs not supported by ``necessary assurances'' of legality under
Federal and State law. California may adopt and seek approval of a
broad range of strategies to promote NAAQS attainment within the State,
including by adopting additional controls for vehicles registered
within the State. But it cannot (at minimum, without providing
necessary assurances) outsource the costs of local attainment to out-
of-state and out-of-country vehicle owners and operators through a
regulation that would, if approved, become federally enforceable
throughout the country in lieu of adopting additional controls for
vehicles registered within the State. Nothing in California's
submission provides necessary assurances that implementing the HD I/M
Regulation in full would not contravene Federal law, and California
continues to maintain that its submission not only can, but must, be
approved and made federally enforceable under the CAA.
While not necessary to the EPA's determination that the SIP
submission fails to provide necessary assurances, the HD I/M Regulation
also arguably discriminates against out-of-state vehicle owners and
operators by externalizing the costs of achieving the local benefits of
NAAQS attainment. Nothing about the regulatory goals of the HD I/M
Regulation required California to extend compliance requirements to
out-of-state vehicles or to make that extension federally enforceable
by seeking approval in the State's SIP. Rather than taking this novel
approach, California could have limited its application to vehicles
registered within the State and adopted additional controls for
vehicles registered within the State (or for other sources that emit
the relevant pollutants), thereby achieving significant progress toward
NAAQS attainment without raising interstate commerce concerns. Indeed,
the HD I/M Regulation includes provisions specific to out-of-state
vehicles, and CARB separately estimated emissions reductions
attributable to in-state and out-of-state vehicles.\24\ The choice to
extend the regulation to out-of-state and out-of-country vehicles was
deliberate and unnecessary to the operation of the regulatory scheme
with respect to vehicles registered within the State. In this way, the
SIP submittal arguably discriminates against out-of-state vehicles by
subjecting them to additional regulatory requirements that apply year-
round and regardless of location in exchange for localized benefits.
California's legitimate objective, reducing emissions to comply with
its NAAQS obligations under Federal law, does not require regulation of
all trucks nationwide that may traverse the State, particularly in a
manner in which the burdens of compliance fall disproportionately on
out-of-state owners and operators as compared to vehicles registered
within the State.\25\ Put another way, extending
[[Page 5329]]
the regulation to out-of-state vehicles serves the illegitimate
objective of outsourcing the costs of attaining the NAAQS within
California to other States and vehicle owners and operators in those
States, rather than identifying additional emissions reduction
strategies within the traditional ambit of purely in-state sources
encompassed within and creditable to the State of California.
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\24\ See Cal. Health & Safety Code Sec. Sec. 44011.6, 44011.7;
see also Staff Report, which breaks out said costs and emissions
estimates by in-state and out-of-state operators.
\25\ See Comment ID EPA-R09-OAR-2025-0061-0044; Comment ID EPA-
R09-OAR-2025-0061-0001 (pointing out the national character of the
proposed regulation). Additionally, commenters asserted that the
regulation imposes itself upon the testing apparatus of other States
and unfairly burdens their residents with compliance. See Comment ID
EPA-R09-OAR-2025-0061-0025 (pointing out infeasibility of out-of-
state testers satisfying CARB). Finally, one commenter points out
that in order to challenge supposed violations, out-of-state
operators ``must request a hearing with the CARB Hearing Coordinator
and make arrangements to return to California'' thus logistically
crippling small business operators with unfair compliance burdens.
Comment ID EPA-R09-OAR-2025-0061-0048.
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The discrimination at issue here is different in kind from the
indirect impacts to interstate commerce permitted by the Supreme
Court's Commerce Clause jurisprudence. In National Pork Producers, the
Court rejected an ``almost per se'' Commerce Clause challenge to a
California law that sought to promote the humane treatment of animals
by barring California merchants from selling non-compliant pork within
California. 598 U.S. at 367 (majority op.); see also id. at 384
(plurality op.) (emphasizing that the law regulated sales within
California and that non-compliant producers remained free to ``withdraw
from that State's market''). In contrast here, the HD I/M Regulation
would, if approved into the SIP, apply directly to and be federally
enforceable against out-of-state and out-of-country vehicle owners and
operators even if they conduct no business in California. Trucks
shipping apples from Washington to Arizona, or export goods from Texas
to ports on the Pacific Ocean, would be obligated to comply merely
because they passed through California. As already discussed, proactive
compliance by many out-of-state interstate shippers would be the only
practicable option to avoid noncompliance and significant fines. This
extraterritorial scope exceeds the localized scope of California's
interest. Nor is California's goal of demonstrating compliance with its
statutory obligations, thereby avoiding potential bump-ups in
nonattainment level by operation of the statute, directly related to
the health, safety, or other interests the Court has recognized as
grounds for permissible in-state regulation imposing indirect out-of-
state burdens. Id. at 374-75 (majority op.). Rather, the out-of-state
reach of the SIP submission is explicitly tied to more effectively
meeting California's obligations under the CAA's NAAQS implementation
provisions, including deadlines for attainment and reclassification.
And the SIP submission's out-of-state reach pursues that goal by
imposing costs on interstate trucking, a function the Court
specifically noted warrants a more exacting analysis. Id. at 379 n.2
(majority op.) (``[T]his Court [has] refused to enforce certain state
regulations on instrumentalities of interstate transportation--trucks,
trains, and the like. . . . Nothing like that exists here. We do not
face a law that impedes the flow of commerce. Pigs are not trucks or
trains.'').\26\
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\26\ As noted at proposal and confirmed in this final action,
the EPA's full approval of the SIP submittal would also threaten to
impose conflicting obligations with respect to I/M requirements.
See, e.g., Exxon Corp. v. Gov. of Md., 437 U.S. 117, 128 (1978)
(distinguishing between the retail market and regulation that
impedes the flow of goods and risks ``that the several States will
enact differing regulations'').
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Regardless of whether the regulation at issue here is
discriminatory, a showing of discrimination is not required under Pike
v. Bruce Church, Inc., 397 U.S. 137 (1970), or related cases. In
National Pork Producers, a majority of the Supreme Court ``le[ft] the
courtroom door open to plaintiffs invoking the rule in Pike, that even
nondiscriminatory burdens on commerce may be struck down on a showing
that those burdens clearly outweigh the benefits of a state or local
practice.'' \27\ And the Court has long recognized special
considerations for instrumentalities of commerce (including interstate
trucking).\28\ This line of cases is directly on-point and demonstrates
that the HD I/M Regulation at issue here warrants careful
consideration. The SIP submittal's intended applicability to interstate
trucking beyond the borders of California (and that which passes
through California, at least on occasion, owing to the nature of the
market) appears to contravene case law evaluating State laws which
impose undue burdens upon the instrumentalities of interstate commerce.
California provided no assurances to the contrary in its SIP submission
and continues to maintain its entitlement to impose such burdens under
the CAA. As articulated in greater detail in our responses to comments
in section III of this preamble, the EPA views the burdens of a fully
approved SIP submission on interstate commerce as significant. Such
significant burdens outweigh the proposed local compliance benefits of
the regulation and therefore run afoul of the Commerce Clause. As one
commenter explained: ``The program's overreach will result in the
potential for de facto regulation of out-of-state rented or leased
trucks across the country even though renting and leasing companies
have no control [over] whether their trucks' routes include traveling
into California. . . . CARB's HD I/M program disproportionately affects
out-of-state rental and leasing company operations and finances . . .
in clear violation of the Dormant Commerce Clause.'' \29\
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\27\ 598 U.S. at 395-96 (Roberts, C.J., concurring in part and
dissenting in part).
\28\ See id. at 379 n.2 (majority op.) (``[T]here exists a
strong line of cases that originated before Pike in which th[e]
Court refused to enforce certain state regulations on
instrumentalities of interstate transportation--trucks, trains, and
the like.''); see, e.g., Bibb v. Navajo Freight Lines, Inc., 359
U.S. 520, 523-30 (1959) (concerning a State law specifying certain
mud flaps for trucks and trailers); S. Pac. Co. v. Arizona ex rel.
Sullivan, 325 U.S. 761, 763-82 (1945) (addressing a State law
regarding the length of trains).
\29\ Comment ID EPA-R09-OAR-2025-0061-0036.
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Unlike virtually all prior CARB regulations and similar regulations
adopted by other States, the HD I/M Regulation would apply to vehicles
registered out-of-state and out-of-country that operate within the
State of California for almost any length of time. Because approval of
a SIP makes its requirements federally enforceable,\30\ the regulation
would, in effect, become a Federal regulation enforceable by the EPA
(and citizen-suit plaintiffs) \31\ against any owner or operator in all
fifty States of any heavy-duty vehicle that may pass through
California.\32\
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\30\ CAA section 110(k).
\31\ CAA sections 113, 304.
\32\ Comment ID EPA-R09-OAR-2025-0061-0035 (highlighting how the
SIP creates duplicative regimes across States increasing compliance
costs); Comment ID EPA-R09-OAR-2025-0061-0047 (demonstrating how
referee locations are ``only found in California'' and therefore
inequitably discriminate against out-of-state residents in both
costs and seeking to comply).
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As addressed in section III of this preamble, Response to Comments,
this would in effect lead to additional compliance costs for heavy-duty
vehicle operators in all jurisdictions. Some States have HD I/M
provisions that differ from California's in material respects, but none
of these have been approved into SIPs.\33\ If approved into the SIP in
all respects, California's HD I/M Regulation would be federally
enforceable to the same extent as other State I/M regulations,
including any that may be approved by the EPA in the future pursuant to
CAA section 110. The result would be multiple conflicting
[[Page 5330]]
sources of obligations that are enforceable both within the respective
States and federally under the CAA.
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\33\ See 6 NYCRR Subpart 217-5 (New York Heavy Duty Inspection
and Maintenance Program), N.J.A.C. 7:27-14 (New Jersey Control and
Prohibition of Air Pollution); ORS 815.200-215 (Oregon motor vehicle
pollution control); see also Comment ID EPA-OAR-2025-0061-0047
(``Existing HD I/M programs, or new programs adopted in the future,
may not all have identical requirements, but any discrepancies are
likely to have an immeasurable impact on air quality outcomes
provided they are target high-emitting vehicles. Greater assurances
are needed that the emissions benefits from these separate programs
are properly accounted for and do not overlap.'').
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Additionally, the SIP would require owners of heavy-duty vehicles
to demonstrate that their vehicle emissions control systems are
properly functioning through vehicle compliance tests completed by
CARB-approved testers and require such owners to periodically submit
vehicle compliance test results to CARB to show compliance with the HD
I/M Regulation. Vehicles equipped with OBD systems would have to be
tested using OBD data, while older non-OBD vehicles would be subject to
smoke opacity and visual inspections. Lastly, vehicle owners would be
required to have a valid HD I/M compliance certificate with the vehicle
while operating in California presentable to a California Highway
Patrol officer upon request. As CAA section 202(m) authorizes the EPA
to regulate and require such OBD systems for heavy-duty vehicles, the
imposition of a State program which would be national in character also
risks intrusion into an area reserved to Federal authority.\34\ The
CAA's requirements and procedures for California to seek and obtain a
preemption waiver, and for other States to adopt California standards
for which preemption has been waived, do not apply to this submission,
and nothing in CAA section 110 suggests that the statute's provisions
for SIP development and submission can function as a workaround for the
requirements of CAA sections 177 and 209.
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\34\ Comment ID EPA-R09-OAR-2025-0061-0019 (highlighting the
creation of conflicting implementation schemes across States imposed
by the SIP); Comment ID EPA-OAR-2025-0061-0018 (out-of-state
residents being fined for non-compliance with limited options in
home State for remediation); Comment ID EPA-R09-OAR-2025-0061-0036
(illustrating how over compliance out of caution is the only
prevention from incurring unknown fines from CARB for out-of-state
operators); Comment ID EPA-R09-OAR-2025-0061-0048 (pointing out the
trespass into Federal authority by CARB's regulation).
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The impact of California's HD I/M Regulation on vehicles registered
out-of-state (and out-of-country) and on interstate shipping is
significant. The HD I/M Regulation adds significant costs to operation
of heavy-duty vehicles even within California. According to the CARB
Staff Report, the HD I/M Regulation will cost $4.12 billion between
2023-2050, with a maximum annual cost of $350 million in 2024. Many of
these costs relate to heavy-duty vehicle testing, repair, and
compliance fees.\35\ But this analysis, which seeks to balance these
costs against the benefits of promoting local NAAQS compliance,
improperly weighs the benefits to California against costs imposed
nationwide. As commenters point out, overcompliance costs and unknowing
violations risk fines and burdens imposed outside the borders of
California. The EPA notes that many heavy-duty vehicles covered by the
regulations at issue are used for purposes of interstate shipping, and
that maintenance of those vehicles could occur in any number of States,
meaning the burdens of compliance could be felt across the country and
even in other countries. The outsourcing of costs and burdens to other
States in pursuit of local benefits via the SIP misunderstands the
ambit of State regulation and the Commerce Clause limits on the State's
powers. The regulatory regime imposed by the SIP, which reports in-
state benefits against conservative estimates of out-of-state burdens,
calls into question the entirety of the State's cost-benefit analysis
as addressed more fully in section III of this preamble.\36\
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\35\ Staff Report at IX-14.
\36\ To cite one example, the Center for Community Action and
Environmental Justice refused in its comment to acknowledge the
modifications needed to CARB's initial cost-benefit estimates in
light of recent resolutions enacted by Congress and signed by the
President to void EPA preemption waivers for three California
mobile-source regulations. The commenter stated without evidence
that this recent legislation is illegal. For that reason, among
others, the record includes inconsistent data and estimates with
respect to the predicted impacts of the HD I/M Regulation. See
Comment ID EPA-R09-OAR-2025-0061-0040.
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Contrary to claims made by some adverse commenters, the EPA need
not specify a less discriminatory approach for California to follow
that would comply with the Commerce Clause and therefore render the SIP
approvable under the CAA.\37\ Under the Pike analysis, the availability
of a less discriminatory approach to achieve a regulatory goal is but
one of many factors a reviewing court may consider in evaluating
whether a State regulation infringes on Federal authority reserved to
Congress by the Commerce Clause.\38\ When relevant, courts generally
place the burden on the regulating State to explain why alternatives
that are less burdensome on interstate commerce and out-of-state
economic activity were not considered and adopted.\39\ The EPA is not
required to identify alternatives in this context, including because
the CAA's requirement for necessary assurances is a mandatory element
of a fully approvable SIP submission. In any event, a less
discriminatory alternative is both apparent and reflected in the
Agency's proposal: California may achieve significant emissions
reductions creditable to NAAQS attainment by implementing the HD I/M
Regulation to vehicles registered within the State and, as necessary
and appropriate, developing additional controls for in-state registered
vehicles and potentially other categories of in-state sources. This
final action approves the SIP submittal to that extent while, at the
same time, disapproving the submittal to the extent that it purports to
infringe on interstate commerce by regulating and burdening interstate
trucking.
---------------------------------------------------------------------------
\37\ See Comment ID EPA-R09-OAR-2025-0061-0039; Comment ID EPA-
R09-OAR-2025-0061-0034; Comment ID EPA-R09-OAR-2025-0061-0019.
\38\ See, e.g., Hughes v. Oklahoma, 441 U.S. 322, 338 (1979)
(invalidating local regulation under the Commerce Clause despite
acknowledging ``nondiscriminatory alternatives [that] would seem
likely to fulfill the State's purported legitimate local purpose'');
Granholm v. Heald, 544 U.S. 460, 493 (2004) (discriminatory state
regulations may be upheld only after findings that nondiscriminatory
alternatives will prove unworkable).
\39\ See, e.g., Am. Bev. Ass'n v. Snyder, 735 F.3d 362, 376 (6th
Cir. 2013) (holding that a Michigan product-labeling requirement
violated the Commerce Clause by requiring a unique to Michigan
labelling system by out-of-state firms ``without the consideration
of other less burdensome alternatives'').
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California's submission does not contain necessary assurances to
demonstrate that the HD I/M Regulation can be implemented if approved
as to out-of-state and out-of-country vehicles without running afoul of
Commerce Clause principles, as required by CAA section 110(a)(2)(E).
The SIP rests on a misunderstanding of the reach of the State's
regulatory authority and the division of authority between the EPA and
the States under the CAA, including CAA section 110. California may
regulate I/M activities for vehicles registered within the State
consistent with Federal law and may submit such regulation for approval
to satisfy the State's NAAQS attainment obligations under Federal law.
But the EPA cannot authorize California to become a de facto Federal
regulator by making the State's HD I/M Regulation federally enforceable
through approval into the SIP. Under the circumstances presented here,
approval of the SIP would not be consistent with CAA section
110(a)(2)(E).\40\
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\40\ Under the Pike balancing test, that aspect of the
regulation appears to place substantial burdens on interstate
commerce that are not justified by local benefits. Nor is it clear
that the State has a legitimate interest in extending the regulation
to out-of-state and out-of-country vehicles for the purpose of
satisfying California's obligations to demonstrate compliance with
the NAAQS. Under established precedent, benign State objectives in
regulation that burdens interstate commerce must balance against the
burdens imposed. See Raymond Motor Transp., 434 U.S. at 445 (finding
a State law banning vehicle length, despite its potential safety
benefits and the presumption of validity afforded to laws passed
within a traditional state domain, to be an unconstitutional burden
to interstate commerce); Burlington N. R. Co. v. Nebraska, 802 F.2d
994, 1001 (8th Cir. 1986) (`` `Regulations designed for [a] salutary
purpose nevertheless may further the purpose so marginally, and
interfere with commerce so substantially, as to be invalid under the
Commerce Clause.' '' (quoting Kassel, 450 U.S. at 670 (plurality
op.)) (holding a State law banning double-trailers unconstitutional
based on interstate burden).
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[[Page 5331]]
In response to the proposal, CARB asserted that the HD I/M
Regulation, including implementation of its provisions with respect to
out-of-state and out-of-country vehicles passing through California, is
necessary to demonstrate attainment with the NAAQS in several of the
State's air quality regions. According to CARB, the regulation is
projected to reduce NO<INF>X</INF> emissions statewide by approximately
81 tons per day in 2037 and 110 tons per day in 2050, and directly
emitted PM<INF>2.5</INF> emissions statewide by approximately 0.7 tons
per day in 2037 and 0.9 tons per day in 2050. CARB does not clearly
delineate between benefits attributable to in-state vehicles and out-
of-state and out-of-country vehicles in this calculation presented in
comment. The HD I/M Regulation is additionally expected to reduce
NO<INF>X</INF> emissions in the South Coast Air Basin by approximately
22 tons per day in 2037 and 29 tons per day in 2050, and directly
emitted PM<INF>2.5</INF> emissions by approximately 0.2 tons per day in
2037 and 2050. Finally the HD I/M Regulation is expected to reduce
NO<INF>X</INF> emissions in the San Joaquin Valley by over 21 tons per
day in 2037 and approximately 30 tons per day in 2050, and directly-
emitted PM<INF>2.5</INF> emissions by approximately 0.2 tons per day in
2037 and 2050. But CARB goes on to admit that these regulations extend
to out-of-state vehicles by stating that ``[o]ver 750,000 vehicles and
260,000 fleets, respectively, are currently registered in the program.
The majority of these vehicles and fleets are registered in
California.'' \41\ Thus, CARB acknowledges that the projected emissions
reductions attributed to the HD I/M Regulation--which it identifies as
needed to discharge statutory obligations to attain the NAAQS--are in
no small part reliant on regulating vehicles registered and primarily
operating outside of the State. In a comment submission, the Union of
Concerned Scientists (UCS) estimates that ``[i]n 2025, out-of-state
vehicles made up at least 13 percent of [heavy duty vehicles] operating
on California's roads and highways [with] . . . out-of-state [vehicles]
. . . responsible for more than 34 percent of NO<INF>X</INF> emissions
and over 39 percent of PM<INF>2.5</INF>.'' \42\ Thus, based on this
comment in support of the HD I/M Regulation, over a third of the
emission reductions benefits for NAAQS compliance are achieved by
impermissibly burdening the citizens and businesses of other States.
---------------------------------------------------------------------------
\41\ Comment ID EPA-R09-OAR-2025-0061-0045.
\42\ Comment ID EPA-R09-OAR-2025-0061-0041; see also Comment ID
EPA-R09-OAR-2025-0061-0042 which estimates that ``[a]pproximately
half of the trucks operating in California are out-of-state or out-
of-country'' before advocating the ``necessit[y] [of] the
applicability of the HDIM program [beyond California] to adequately
address harmful emissions.'' This comment seems to suggest that
California has the authority to seek to regulate all jurisdictions
globally under this program and should seek to exercise such
authority.
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Relatedly, the EPA determines that California's submission cannot
be approved in full because it conflicts with CAA section 110 and
related provisions of the statute. The EPA's concern in this respect is
heightened by the structure of CAA section 110 and the way in which a
full approval of the HD I/M Regulation would operate on the ground. In
effect, an approval would delegate to California the ability to enforce
the State's I/M requirements throughout the nation to the extent a
vehicle passes through or operates within the State for virtually any
length of time. As commenters make clear, the nature of the trucking
industry ensures that almost all out-of-state operators would be forced
into compliance to avoid unknowing and incidental violations of these
requirements. As a result, an approval would effectively force
regulated entities in other States to comply with California's HD I/M
requirements, rather than the applicable requirements in their
respective States, including requirements approved by the EPA pursuant
to the CAA.\43\ That interstate regulatory function is vested
exclusively in Congress by the Commerce Clause, and the result of the
EPA's approval under the circumstances risks precisely the abrogation
of Federal authority that the Supreme Court has held the Commerce
Clause prohibits.
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\43\ As noted elsewhere in this preamble and by commenters,
burdens on out-of-state and out-of-country owners and operators
would be more significant than for in-state vehicles to the extent
CARB-approved testers and other necessary compliance steps are not
readily available outside California.
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The Commerce Clause analysis discussed in this section follows from
the Supreme Court's recognition that the Clause contains ``a negative
command'' that forbids ``certain state [economic regulations] even when
Congress has failed to legislate on the subject.'' Okla. Tax Comm'n v.
Jefferson Lines, Inc., 514 U.S. 175, 179 (1995). Here, Congress has
affirmatively legislated on the subject by providing the framework for
States to implement CAA requirements for attaining the NAAQS, subject
to EPA approval. CAA section 110 requires ``[e]ach State'' to ``adopt
and submit to the Administrator . . . a plan which provides for
implementation, maintenance, and enforcement'' of the NAAQS ``within
such State.'' \44\ In addition to the role carved out for ``[e]ach
State,'' Congress vested the EPA with exclusive authority to promulgate
standards and regulations relevant to attainment, including the NAAQS
themselves under CAA sections 108 and 109 and generally applicable
regulations that lower emissions under CAA sections 111 and 202, among
other provisions. As discussed at proposal, approving California's HD
I/M Regulation in full--and thereby making it federally enforceable--
interferes with this statutory scheme by placing California in the
driver's seat across all fifty States.
---------------------------------------------------------------------------
\44\ CAA section 110(a)(1).
---------------------------------------------------------------------------
If approved, California's regulation would be federally enforceable
against any heavy-duty vehicle that may pass through California,
although those vehicles may already be subject to I/M regulations
applicable in the State of registration. Thus, a vehicle registered in
any other State would be subject to both its own local state laws and
the California SIP overlaid and enforceable under Federal law.
California law would effectively take precedence over any other
State's, and over applicable EPA regulations.
In addition, approval of California's regulation would create an
inherent tension with any other State seeking to adopt an HD I/M
regulation into a SIP as part of an emissions reduction strategy.
Courts have held that all measures used to attain the NAAQS must be
included in the relevant State's SIP.\45\ If another State seeks SIP
approval for an HD I/M regulation that is less stringent than or
different from California's, and if the EPA approves such a SIP
submission, vehicles may be subject to multiple federally enforceable
I/M requirements that differ from or contradict each other. And if the
EPA denies such a SIP submission by another State in order to avoid
this result, the approval of California's SIP submission will have
effectively barred other States from utilizing the same strategy as
California to comply with Federal NAAQS obligations under CAA section
110. California alone would be able to benefit its own residents in
complying with NAAQS requirements at the expense of other States'
residents.
[[Page 5332]]
Nor do the CAA's SIP provisions contemplate California using its SIP
submission to pressure other States seeking to obtain emissions
reductions from an I/M program to adopt regulations identical to
California's. Even if another State submitted an identical regulation,
it would be unclear whether and how much emissions reductions could be
attributed to that State's SIP rather than California's program. The
CAA provides specific requirements and procedures where California
seeks to obtain a preemption waiver and other States seek to follow
California's regulations--CAA sections 177 and 209--that are not
applicable to this SIP submission under CAA section 110.
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\45\ See Comm. for a Better Arvin v. EPA, 786 F.3d 1169, 1176-77
(9th Cir. 2015).
---------------------------------------------------------------------------
Therefore, pursuant to CAA section 110(k)(3), the EPA is partially
approving the HD I/M Regulation into the California SIP to the extent
the regulation applies to vehicles registered in the State. This
partial approval action incorporates into the California SIP the
submitted regulations in table 1 of this preamble and will replace the
Heavy-Duty Vehicle Inspection Program \46\ (HDVIP) and Periodic Smoke
Inspection Program \47\ (PSIP) that were previously approved by the EPA
into the California SIP.\48\ Our partial approval will also incorporate
into the SIP the OBD Standards document that is incorporated by
reference through the HD I/M Regulation.
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\46\ CCR Title 13, Division 3, Chapter 3.5.
\47\ CCR Title 13, Division 3, Chapter 3.6.
\48\ 87 FR 27949 (May 10, 2022).
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Our partial disapproval of the HD I/M Regulation will not result in
imposition of either sanctions or a Federal Implementation Plan (FIP).
Sanctions are not imposed under CAA section 179(b) because the
submittal of the HD I/M Regulation is discretionary (i.e., not required
to be included in the SIP), and the EPA need not promulgate a FIP under
CAA section 110(c)(1) because the partial disapproval does not reveal a
deficiency in the SIP that such a FIP must correct. The submitted
regulation has been adopted by the State of California, and our partial
disapproval will not by its own force prevent the State from enforcing
it within California as a matter of State law.\49\
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\49\ The EPA's role in this action is limited to determining
whether and to what extent the SIP submission is approvable. That
analysis turns on determining whether the SIP submission satisfies
all applicable requirements of the CAA, including the requirement
that California provide ``necessary assurances'' that the SIP could
be implemented consistent with Federal and State law. Thus, this
final action is not a determination of the constitutionality of the
HD I/M Regulation and should not be read as purporting to decide
whether California may, consistent with the Commerce Clause,
continue to enforce the regulation as a matter of State law.
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III. Response to Public Comments and Discussion
The EPA's proposed rulemaking provided a 30-day public comment
period, in which we sought comments on all aspects of the proposal,
including both proposed alternatives and related issues. During this
period, we received a total of 42 comments. This section summarizes and
responds to all comments that are germane to this action.\50\
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\50\ The comments included one non-germane comment, which we
have not addressed, and one comment that included profanity, which
we have not addressed and which is not included in the docket for
this action. See ``Commenting on EPA Dockets,'' <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a>.
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A. Comments in Support of Partial Disapproval
Comment 1: General Support for Partial Disapproval
Several commenters expressed general support for the EPA's proposed
partial disapproval of the HD I/M Regulation as applied to vehicles
registered outside the State of California for the reasons addressed in
the proposed rulemaking. These reasons relate to the EPA's substantial
concerns that California had not provided necessary assurances of
adequate authority under CAA section 110(a)(2)(E)(i) to implement the
HD I/M Regulation as it applies to vehicles registered in other States
and other countries consistent with Federal law, including the Commerce
Clause and foreign relations powers provisions of the U.S.
Constitution, as well as substantial concerns that EPA approval of the
HD I/M Regulation could result in conflicts with provisions of other
States' SIPs.
Response: The EPA appreciates these comments. For reasons addressed
in this preamble and consistent with the primary proposal, we are
finalizing a partial approval and partial disapproval of the HD I/M
Regulation.
Comment 2: Burdens to Interstate Commerce
Several commenters described specific burdens to interstate
commerce that they believed supported partial disapproval of the HD I/M
Regulation, including costs to out-of-state vehicles and the industry
generally, and difficulties associated with compliance.
The National Tank Truck Carriers (NTTC) expressed concerns related
to operational feasibility, noting logistical and legal uncertainty
associated with applying the HD I/M Regulation to vehicles registered
outside of California. The commenter described negative impacts of
California's Advanced Clean Trucks (ACT) and Low NO<INF>X</INF> Omnibus
regulations, and stated that applying similar rules to out-of-state
vehicles would undermine emission reduction goals and increase costs
and operational inefficiencies.
The Bennett Family of Companies described costs associated with
testing equipment, testing certification, downtime, administrative
burdens, and equipment requirements, which they argue harms efficiency
and competitiveness in interstate trade. The commenter also cited
delays resulting from roadside enforcement compliance checks and
restrictions on non-compliant vehicles, and associated supply chain
disruptions particularly for time sensitive freight and deliveries, and
noted inefficiencies associated with conflicting State requirements.
The American Trucking Associations (ATA) also described impacts of
delays and difficulties associated with testing requirements especially
for out-of-state fleets that are located far away from testing
facilities and referee services and noted that fleets are sometimes
classified as non-compliant despite their best efforts to comply. The
commenter stated that the cost and time needed to test vehicles that
operate in California for only a few hours or days likely outweigh the
emissions benefits to California.
The Owner-Operator Independent Drivers Association (OOIDA)
described costs associated with compliance as well as fines for
noncompliance, and noted practical difficulties for operators based
outside of California to challenge citations issued under the
regulations. The commenter included examples of citations issued to
businesses located outside of California.
Several commenters noted that costs and penalties associated with
the HD I/M Regulation may disproportionately impact small carriers and
owner-operators who lack resources to absorb the added expenses.\51\
Small proprietors also commented on the disproportionate burdens to
interstate commerce they would suffer in being forced of necessity to
treat the HD I/M Regulation as a national standard mandating fleet
replacement, out-of-state permitting hurdles, fines levied against non-
California-based businesses, and downstream burdens to other industries
[[Page 5333]]
in need of transportation services.\52\ One example provided in a
comment from the Truck Renting and Leasing Association (TRALA),
explains how a business with an out-of-state rented or leased truck may
not even be aware of its fleets operation in California until ``the
owner's receipt of a CARB citation . . . [s]uch citations can lead to
enforcement actions with potential fines reaching up to $10,000 per
day.'' \53\ Finally, a comment from the California Trucking Association
explains the unaccounted for administrative burdens caused by
enforcement of the HD I/M Regulation and the practical impossibility of
certain carriers to usefully comply with the regulation as
promulgated.\54\
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\51\ See generally Comment ID EPA-R09-OAR-2025-0061-0048.
\52\ See generally Comment ID EPA-R09-OAR-2025-0061-0015;
Comment ID EPA-R09-OAR-2025-0061-0016; Comment ID EPA-R09-OAR-2025-
0061-0018.
\53\ Comment ID EPA-R09-OAR-2025-0061-0001.
\54\ See generally Comment ID EPA-R09-OAR-2025-0061-0037.
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Response: The EPA recognizes the substantial compliance costs
associated with the HD I/M Regulation, including those to vehicles
registered outside the State, and the accompanying burdens to
interstate commerce, including those that are unique to or more
significant for out-of-state and out-of-country registered vehicles.
The impact of California's HD I/M Regulation on vehicles registered
out-of-state and on interstate shipping is undoubtably significant. The
HD I/M Regulation adds significant costs to operation of heavy-duty
vehicles registered in California. According to a CARB \55\ Staff
Report, the HD I/M Regulation will cost $4.12 billion between 2023-
2050, with a maximum annual cost of $350 million in 2024. Much of these
costs relate to heavy-duty vehicle testing, repair, and compliance fee
costs.\56\ CARB estimated the total direct costs on single-vehicle
fleets and ``typical'' (i.e., seven-vehicle) fleets. But as articulated
by the above comments, CARB's analysis does not properly account for
the myriad costs imposed on out-of-state operators forced to comply
with the regulatory program. The cumbersome reporting obligations,
fleet updating, and narrow windows for reporting impose additional
costs to out-of-state vehicle operators.\57\ To the extent the HD I/M
Regulation applies to out-of-state and out-of-country vehicles that
pass through California for almost any length of time, this cost
structure would also be imposed on other States and regulated entities
in those States. The EPA notes that many heavy-duty vehicles covered by
the regulations at issue are used for purposes of interstate shipping,
and that maintenance of those vehicles could occur in any number of
States, meaning the burdens of compliance could be felt across the
country and even in other countries. The overcompliance which the
commenters assert such a regime will create represents unwarranted and
substantial burdens on out-of-state fleets.\58\
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\55\ Staff Report at IX-14.
\56\ Staff Report at IX-18 through 20. CARB states that,
according to vehicle registration data, of fleets consisting of at
least three vehicles, 75 percent have four to ten vehicles.
\57\ See generally Comment ID EPA-R09-OAR-2025-0061-0037;
Comment ID EPA-R09-OAR-2025-0061-0048.
\58\ Comment ID EPA-R09-OAR-2025-0061-0037.
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As described in this preamble, our partial disapproval of the HD I/
M Regulation considers these costs among other considerations and finds
that the substantial burdens placed upon out-of-state instrumentalities
of interstate commerce appear to run afoul of the Commerce Clause as
explained below in further response to comments. CAA section
110(a)(2)(E) provides that a SIP must include ``necessary assurances''
that the State ``is not prohibited'' by any Federal law, and California
has not provided such assurances. In accessing compliance with the
Federal Constitution, the cost burdens of the SIP support the need for
partial disapproval.
While not directly relevant to this rulemaking, we would like to
clarify in response to NTTC's comment regarding California's ACT and
Low-NO<INF>X</INF> Omnibus regulations that the HD I/M Regulation does
not and legally cannot expand the scope of these regulations to any
additional vehicles or areas. These measures were permitted to go into
effect by EPA waivers of preemption that were disapproved by Congress
and the President under the Congressional Review Act in 2025 and are
therefore preempted and without legal force.\59\
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\59\ See H.J. Res 87 (April 30, 2025) (disapproving April 6,
2023 waiver for ACT); H.J. Res 89 (April 30, 2025) (disapproving
January 6, 2025 waiver for Low-NO<INF>X</INF> Omnibus). On June 12,
2025, President Trump signed these Congressional Review Act
resolutions disapproving the waivers. See also Statement by the
President June 12, 2025, <a href="https://www.whitehouse.gov/briefings-statements/2025/06/statement-by-the-president/">https://www.whitehouse.gov/briefings-statements/2025/06/statement-by-the-president/</a>.
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Comment 3: Discrimination Under Commerce Clause; Less Burdensome
Approaches
Several commenters specifically argued that the HD I/M Regulation
violates the Commerce Clause under applicable judicial interpretations,
including the presence of less burdensome regulatory approaches.
TRALA argued that the HD I/M Regulation is discriminatory under the
Dormant Commerce Clause because it compels out-of-state rental and
leasing businesses to ``over-comply'' for vehicles that do not enter
California in order to ensure that their fleet is in full compliance,
because the regulations do not differentiate between the amount of
emissions generated by specific trucks (including out-of-state trucks
traveling minimally in California), and because requirements to induce
vehicle maintenance included in Federal heavy-duty emissions standards
enacted in 2022 represent a less discriminatory alternative.
The California Trucking Association (CTA) and ATA suggested
alternative regulatory approaches raised during CARB's development of
the HD I/M Regulation that they argue would be less burdensome. These
include exemptions for new vehicles, and measures to focus testing and
enforcement resources on fleets and vehicles identified as high
emitters, and changes to the reporting schedule to better accommodate
the time between purchase and physical delivery of new vehicles.
Response: As a general matter, alternative regulatory approaches
are outside the scope of this action for reasons described throughout
this preamble, including in response to Comment 17. However, the EPA
recognizes that courts have considered the availability of less
discriminatory approaches as part of Dormant Commerce Clause analysis
in some situations. Under the Pike balancing test, whether a less
discriminatory approach to a regulatory goal was available is but one
of many factors a reviewing court may consider in evaluating whether a
regulation violates the Commerce Clause. Regardless of that analysis
and whether the HD I/M Regulation at issue here could be found to be
discriminatory, the assurances provided for the HD I/M Regulation do
not satisfy CAA section 110(a)(2)(E)'s requirement that the proposed
SIP include necessary assurances that its implementation would not
violate Federal law. Regardless of alternative approaches, the portion
disapproved by the EPA in this final action appears to fail the current
test for a nondiscriminatory law by placing an improper burden on
interstate commerce as prohibited by the Commerce Clause and applicable
provisions of the CAA representing Congress' affirmative legislation on
the subject. California has not provided necessary assurances to the
contrary. As explained previously, there are obvious alternatives for
California to achieve its goal of discharging NAAQS-related obligations
under Federal law that do
[[Page 5334]]
not raise similar constitutional and statutory concerns.
In response to comments from TRALA, we note that the HD I/M
Regulation includes a 5-day ``pass-through'' exception once per
calendar year for individual vehicles that travel only minimally within
the State. For a fuller articulation of why this yearly ``pass-
through'' provision does not alter the HD I/M Regulation's national
reach or burdens to interstate commerce, please see the discussion in
response to Comment 8 and discussion elsewhere in this preamble.
Comment 4: Specific Conflicts With Other State Rules
ATA stated that other counties and States maintain annual or semi-
annual inspection and maintenance programs as part of their truck
registration process requirements, citing programs in Colorado, New
York, and New Jersey. The commenter noted that the HD I/M Regulation
presumes noncompliance even for trucks that were recently inspected in
another area. The commenter described these programs as redundant and
costly, and argued that they raise concerns regarding claimed program
benefits.
Response: We appreciate this comment. As described in the preamble
to the proposed rule and in this preamble, we considered the
possibility of conflicts with other States' laws as a basis for our
final action. The EPA is partially disapproving the SIP submission
because California has not provided necessary assurances that the
extraterritorial reach of the HD I/M Regulation into other States and
burdens imposed on interstate commerce do not violate CAA section 110
and related provisions by infringing upon, or frustrating the
implementation of, SIPs submitted by other States and reviewed by the
EPA. If approved in all respects, California's HD I/M Regulation would
be federally enforceable to the same extent as other State I/M
regulations potentially approved by the EPA in the future pursuant to
CAA section 110. The result is potentially multiple conflicting sources
of obligations that are enforceable both within the respective States
and federally under the CAA.
B. Comments in Support of Full Approval
Comment 5: General Support for Full Approval
Several commenters expressed support for the EPA's alternative
proposal to fully approve the HD I/M Regulation, including its
application to out-of-state and out-of-country vehicles, for the
reasons addressed in the preamble to the proposed rulemaking. These
comments generally argued that the submittal complies with the CAA and
applicable regulations, including in particular that California has
provided necessary assurances that it has adequate authority to
implement the HD I/M Regulation and that implementation of the HD I/M
Regulation would not be prohibited by Federal or State law, as required
by CAA section 110(a)(2)(E)(i).
Response: The EPA acknowledges these comments. However, for reasons
addressed in the preamble to the proposed rulemaking and this preamble
pertaining to the requirement that SIPs must meet all applicable CAA
requirements--specially including ``necessary assurances'' that the
State is not prohibited by any Federal law from carrying out the
implementation of the SIP--we are finalizing a partial approval and
partial disapproval of the HD I/M Regulation. The State did not provide
necessary assurances that implementation of the HD I/M Regulation as
applied to all non-gasoline combustion vehicles above 14,000 lbs that
pass through California, including vehicles registered out-of-state and
out-of-country, would not be prohibited by Federal law.
Comment 6: Other Practical Considerations Supporting Full Approval
Several commenters described health and environmental benefits
associated with the HD I/M Regulation, as well as other practical
considerations in favor of the HD I/M Regulation and/or its approval
into the SIP, including those related to the role of the emissions
reductions associated with the HD I/M Regulation in regional attainment
planning in California. Commenters described health impacts associated
with ozone and PM<INF>2.5</INF> emissions, including disease and
premature death, and cited a need for reductions of ozone,
PM<INF>2.5</INF>, and their precursors particularly within the South
Coast and San Joaquin Valley nonattainment areas. Commenters described
the role of emissions from heavy-duty vehicles generally and from out-
of-state heavy-duty vehicles in particular, citing figures from CARB's
SIP submittal and other sources. Commenters pointed to predicted
reductions in PM<INF>2.5</INF> and NO<INF>X</INF> associated with the
HD I/M Regulation, which commenters asserted are relied upon in several
PM<INF>2.5</INF> and ozone plans, and argued that it would be difficult
and costly to obtain equivalent reductions from other mobile or
stationary sources. Commenters also cited confusion, regulatory
uncertainty, and other practical concerns that could result from
partial disapproval of the HD I/M Regulation.
The Center for Community Action and Environmental Justice and
Sierra Club (collectively, ``CCAEJ'') argued that a partial disapproval
of the HD I/M Regulation would reduce the amount of SIP creditable
emissions reductions from the HD I/M Regulation, and that the EPA would
be obligated to promulgate a FIP if California fails to submit an
attainment demonstration or if the EPA disapproves an attainment
demonstration that the State fails to correct.
One anonymous commenter argued that heavy-duty trucks emit the same
pollutants regardless of where they are registered, and that not
regulating out-of-state vehicles would create a ``regulatory loophole''
that would unfairly burden in-state vehicles and undermine the State's
ability to address air pollution.
The UCS argued that partial disapproval would be inconsistent with
the EPA's commitment to ensuring that Americans have access to clean
air, as described in the first ``pillar'' of the ``Powering the Great
American Comeback'' Initiative announced in a recent EPA press release.
CARB argued that the HD I/M Regulation has been successfully
implemented and has achieved emissions reductions as designed, citing
statistics regarding vehicle registration, testing and monitoring
results, and costs, and that the HD I/M Regulation is consistent with
other CARB in-use regulations that the EPA has previously approved into
the SIP. The commenter argued that partial disapproval of the HD I/M
Regulation would transfer the obligation to obtain emissions reductions
in part to sources regulated primarily by the Federal Government.
Response: We appreciate the considerations raised by the
commenters. However, the question before the EPA in this final action
is whether the SIP submission may be fully approved, and therefore made
federally enforceable, because it does or does not satisfy all
applicable requirements of the CAA. The CAA does not authorize the EPA
to approve or adopt any provision simply because it may result in
projected emissions reductions. For the reasons addressed in the
preamble to the proposed rulemaking and in this preamble, we are
finalizing a partial approval and partial disapproval of the HD I/M
Regulation based on our findings that application of the HD I/M
Regulation to vehicles registered outside California does not
[[Page 5335]]
meet the applicable criteria for SIP approval.
The EPA does not agree with commenters' assertions that the SIP
submission being partially disapproved is consistent with other CARB
regulations that have been approved into California's SIP. As noted
elsewhere in this preamble, the EPA sought comment at proposal whether
California or any other State had received approval for the portion of
the SIP submission at issue here, i.e., the application of an I/M
program in one State to vehicles registered and primarily operating
out-of-state and out-of-country. Commenters did not provide, and the
EPA is not aware of, any examples of a State attempting to assert such
regulatory authority nationwide or of the Agency making such a
submission federally enforceable by approval into a SIP. The submission
before us is novel in this respect, and commenters arguing that the
regulation operates similarly to prior I/M programs fail to grapple
with this unprecedented distinction or the way this novel submission
has forced the EPA to grapple with the issues addressed at proposal and
in this preamble for the first time.
Furthermore, as explained in this preamble, partial disapproval of
the HD I/M Regulation will not result in the imposition of sanctions or
require the promulgation of a FIP. Sanctions are not imposed under CAA
section 179(b) because the submittal of the HD I/M Regulation is
discretionary (i.e., not required to be included in the SIP), and the
EPA need not promulgate a FIP under CAA section 110(c)(1) because the
partial disapproval does not reveal a deficiency in the SIP that such a
FIP must correct. CAA section 110 places the responsibility to
implement the NAAQS on ``each State'' in the first instance, and
partial disapproval of the HD I/M Regulation does not trigger a FIP
obligation under the statute because this particular submittal is not
mandated by the statute. The submitted regulation has been adopted by
the State of California, and our partial disapproval will not by its
own force prevent the State from enforcing it within California as a
matter of State law, as discussed previously. Commenters incorrectly
assumed that California's only path to attainment is through the
disproved portion of the SIP submission. Rather, as discussed elsewhere
in this preamble, California retains discretion to design programs that
promote NAAQS attainment, so long as those programs are consistent with
applicable law. This partial disapproval does not prevent California
from pursuing additional reductions through controls on in-state mobile
or stationary sources that do not raise the same constitutional and
statutory concerns.\60\ If and when California develops such
strategies, it must submit them to the EPA for approval to be credited
for emissions reductions in connection with NAAQS attainment.
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\60\ CCAEJ cites the Ninth Circuit's decision in Committee for a
Better Arvin for the proposition that ``all measures on which a SIP
relies to comply with the Act must be approved by EPA as part of the
SIP.'' Comment ID EPA-R09-OAR-2025-0061-0040. But in that case, the
EPA approved a SIP with control strategies based ``in significant
part on reductions that [would have] been achieved through waiver
measures'' that were not included in the SIP itself and therefore
were not enforceable under the CAA's citizen suit provisions. 786
F.3d at 1176. Nothing in Committee for a Better Arvin stands for the
proposition that the EPA must approve an unapprovable SIP
submission. Rather, that case supports the EPA's position here by
establishing that California and other States cannot be credited for
emissions reductions in support of NAAQS attainment unless the
relevant control strategies have been included in an approved SIP,
which means that the control strategies are consistent with
applicable CAA requirements.
---------------------------------------------------------------------------
Because we are partially approving the SIP submission to the extent
the HD I/M Regulation applies to vehicles registered within the State,
this final action allows California to receive credit for those
emissions reductions and does not disrupt ongoing implementation
efforts within the State as to such vehicles. Additional considerations
relating to the benefits of the HD I/M Regulation as relevant to
Commerce Clause considerations are provided in our response to Comment
7.
Comment 7: Dormant Commerce Clause--Pike Balancing
Several commenters questioned the EPA's proposed basis for partial
disapproval related to concerns that the extraterritorial reach of the
HD I/M Regulation is prohibited by the Commerce Clause of the U.S.
Constitution. Commenters cited caselaw establishing the Supreme Court's
approach to evaluating Commerce Clause issues, including the balancing
test outlined in Pike. Commenters also pointed to cases considering
what kinds of State regulatory burdens to out-of-state interests could
run afoul of a Commerce Clause analysis.\61\ Commenters argued
generally that the HD I/M Regulation does not discriminate against
interstate commerce either facially or in purpose or effect, asserting
that the HD I/M Regulation generally applies the same requirements to
in-state and out-of-state vehicles and does not otherwise economically
advantage in-state vehicles or interests. Several commenters described
the HD I/M Regulation as providing a ``level playing field'' for in-
state and out-of-state vehicles, while others argued that the HD I/M
Regulation is more stringent for in-state fleets and vehicles because
of the ``5-day pass'' option available to out-of-state vehicles and
because of supposedly lower compliance costs for out-of-state fleets.
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\61\ See, e.g., Bibb, 359 U.S. at 523-30 (concerning a State law
specifying certain mud flaps for trucks and trailers); S. Pac. Co.,
325 U.S. at 763-82 (addressing a State law regarding the length of
trains).
---------------------------------------------------------------------------
Several commenters criticized the EPA's analysis for failing to
consider in-state benefits of the HD I/M Regulation as documented in
the materials included with the State's SIP submittal, arguing that
this information is relevant to the Pike balancing test or otherwise
needed for a Commerce Clause analysis. Commenters argued that the
compliance burdens associated with the HD I/M Regulation are not
``clearly excessive'' relative to local benefits, and that the HD I/M
Regulation therefore does not violate the Commerce Clause as applied to
out-of-state trucks.
The South Coast Air Quality Management District (SCAQMD) stated
that conservative estimates show the health benefits of the HD I/M
Regulation to be approximately 11 times the compliance costs. Other
commenters described benefits of HD I/M Regulation exceeding costs by
approximately 18 times based on CARB estimates included in the SIP
submittal, while noting that CARB expects HD I/M Regulation to result
in additional benefits not included in that calculation. CCAEJ
estimated the benefits of the HD I/M Regulation as applied to vehicles
registered outside of California to exceed costs for those vehicles by
more than 10 times, citing CARB estimates of the impact of vehicles
registered outside of California.
The Center for Applied Environmental Law and Policy, Environmental
Defense Fund, and Natural Resources Defense Council (collectively,
``CAELP'') cited previous unsuccessful Commerce Clause challenges to
California pollution-control measures and argued that similar claims
brought against the HD I/M Regulation would fail for the same reasons.
The commenter also noted that CARB received comments during its
development of the HD I/M Regulation that alleged Commerce Clause
violations associated with the $30 compliance fee, and that CARB's
response to these comments was consistent with Supreme Court case law
that the commenter described as allowing State regulators to charge a
flat regulatory fee on interstate commercial trucks.
[[Page 5336]]
CARB offered arguments that the HD I/M Regulation complies with the
Commerce Clause and is well within the State's authority. The commenter
highlighted the Supreme Court's recent decision in National Pork
Producers and other cases.\62\ The commenter argued that the HD I/M
Regulation does not regulate extraterritorially, that the identified
burdens are not ``substantial'' or ``significant'' enough to trigger
application of the Pike balancing test, and that the HD I/M Regulation
does not involve discrimination or serious disruptions in the flow of
interstate goods. Even if Pike balancing were appropriate, the
commenter said, the benefits associated with the HD I/M Regulation
overwhelm the burdens, and the EPA's supposed failure to consider those
benefits would be arbitrary and capricious. Finally, the commenter
argued that benefits associated with the HD I/M Regulation would carry
added weight in a balancing test because they relate to Federal
legislative and executive branch CAA policy.
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\62\ See Comment ID EPA-R09-OAR-2025-0061-0045 (``To the extent
that other burdens--having nothing to do with discrimination--are
cognizable under Pike, it is ``only when a lack of national
uniformity would impede the flow of interstate goods.'' (citing 397
U.S. at 380 n.2)). As explained below, however, this lack of
national uniformity and proliferation of burdens on interstate
trucking is precisely the concern raised by the application of the
HD I/M Regulation to out-of-state and out-of-country registered
vehicles, particularly if made federally enforceable by approval
into California's SIP. Unlike, for example, the Supreme Court's
decision in Exxon Corp. v. Governor of Maryland, 437 U.S. 117, 127-
28 (1978), the HD I/M Regulation would not apply only to activities
within the State and would impact interstate shipping beyond
California's borders. Commenters' citation to California Trucking
Ass'n v. Bonta, No. 24-2341, 2025 WL 1419921 (9th Cir. May 16, 2025)
(unpub.), is equally unpersuasive, since that case involved a State
law governing truck driver classifications as independent
contractors. This case had nothing to do with trucks as
instrumentalities of interstate commerce and does not implicate Pike
or its antecedents.
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Response: At proposal, the EPA noted that the Supreme Court's
Commerce Clause jurisprudence forbids State laws that place burdens on
interstate commerce that are ``clearly excessive in relation to the
putative local benefits.'' \63\ Additionally, in National Pork
Producers, ``six Justices of [the] Court affirmatively retain[ed] the
longstanding Pike balancing test for analyzing Dormant Commerce Clause
challenges to state economic regulations.'' \64\ A plurality of the
Court affirms that ``[they] generally leave the courtroom door open to
plaintiffs invoking the rule in Pike, that even nondiscriminatory
burdens on commerce may be struck down on a showing that those burdens
clearly outweigh the benefits of a state or local practice.'' \65\ This
is especially relevant here as the Supreme Court recognized special
considerations for instrumentalities of commerce (including interstate
trucking).\66\ This line of cases is directly on-point and suggests
that the HD I/M Regulation at issue here must receive particularly
close review. The submittal's intended applicability to interstate
trucking--i.e., operators, businesses, and trucks registered out-of-
state and out-of-country that merely pass through California--facially
and directly burdens interstate commerce with significant costs and
uncertainties. As noted previously, this concern is not limited to the
Pike analysis or even to Commerce Clause constraints on State
authority. Here, Congress has legislated on the subject to providing
that ``each State'' must develop its own plans for implementing the
NAAQS ``within'' its borders and that the EPA, rather than California
or any State, is authorized to establish national standards that
``level the playing field'' and further nationwide environmental goals.
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\63\ Pike, 397 U.S. at 142.
\64\ 598 U.S. at 403 (Kavanaugh, J., concurring in part and
dissenting in part); see id. at 391 (Sotomayor, J., joined by Kagan,
J., concurring in part); id. at 394 (Roberts, C.J., joined by Alito,
Kavanaugh, and Jackson, JJ., concurring in part and dissenting in
part).
\65\ Id. at 396 (Roberts, C.J., concurring in part).
\66\ See id. at 379 n.2 (``[T]here exists a strong line of cases
that originated before Pike in which th[e] Court refused to enforce
certain state regulations on instrumentalities of interstate
transportation--trucks, trains, and the like.''); see, e.g., Bibb,
359 U.S. at 523-30 (concerning a State law specifying certain mud
flaps for trucks and trailers); S. Pac. Co., 325 U.S. at 763-82
(addressing a State law regarding the length of trains).
---------------------------------------------------------------------------
None of the cases relied upon by adverse commenters support the
overbroad contention that the HD I/M Regulation is immune to the
``necessary assurances'' analysis involving the Commerce Clause and the
reach of State regulation because, in commenters' view, it is non-
discriminatory, does not regulate outside California's borders, and
does not unduly burden interstate commerce. For example, CAELP cites
several cases that did not decide whether the regulations at issue were
infirm under the Pike balancing test \67\ and did not involve a
regulatory context where, as here, out-of-state and out-of-country
registered vehicles must comply with the State's regulatory
requirements in other States.\68\ Moreover, these commenters mistake
the relevant analysis here--whether California provided ``necessary
assurances'' that its SIP could, if fully approved, be implemented
consistent with Federal law--for the distinct question whether courts
would invalidate the HD I/M Regulation if presented with constitutional
claims. We do not purport to be adjudicating the ultimate
constitutionality of the HD I/M Regulation and, by the same token, need
not determine that a reviewing court would be certain to invalidate the
regulation if presented with such claims in order to conclude that
California failed to provide ``necessary assurances'' that
implementation could proceed lawfully if the regulation were approved
in full and made federally enforceable. At least one of the cases cited
by commenters recognized that the State's regulation ``pushes a state's
legal authority to its very limits,'' \69\ and the CAA does not require
the EPA to identify those limits with precision before concluding that
a SIP submission is not supported by ``necessary assurances'' of
legality.\70\ Moreover, commenters' arguments do not address the
propriety of California's HD I/M Regulation under the CAA, which as a
matter of text and structure does not support the conclusion that one
State may obtain additional creditable emissions reductions by
obtaining approval of a SIP that renders its program mandatory and
enforceable in other States against owners and operators registered in
those States who
[[Page 5337]]
may traverse California at some point in time.
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\67\ Comment ID EPA-R09-OAR-2025-0061-0043; see Rocky Mt.
Farmers Union v. Corey, 730 F.3d 1070 (9th Cir. 2013) (reversing
district court finding of discrimination but remanding for analysis
under Pike); Pac. Merch. Shipping Ass'n v. Goldstene, 639 F.3d 1154
(9th Cir. 2011) (affirming denial of summary judgment of certain
constitutional claims regarding marine vessel regulations without
addressing Pike); Cent. Valley Chrysler-Keep v. Witherspoon, 456 F.
Supp. 2d 1160, 1183-86 (C.D. Cal. 2006) (granting judgment on the
pleadings against challenge to certain CARB emission standards on
the ground that Congress authorized California to adopt and enforce
such regulations if granted a waiver by the EPA under CAA section
209(b)).
\68\ See Rocky Mt. Farmers, 730 F.3d at 1080 (addressing fuel
standards that applied to fuels used ``within the California
market''); Pac. Merch. Shipping Ass'n, 639 F.3d at 1158-60
(addressing marine vessel regulation that required use of cleaner
fuels within California territorial waters).
\69\ Pac. Merch. Shipping Ass'n, 639 F.3d at 1162.
\70\ While not necessary to the basis for this partial
disapproval, the EPA notes that courts often construe statutes,
including those administered by the Agency, to avoid constitutional
concerns without determining whether the contrary interpretation
would certainly result in a constitutional violation. See, e.g.,
Inhance Techs., L.L.C. v. EPA, 96 F.4th 888, 893-95 (5th Cir. 2024)
(citing, among other cases, Jennings v. Rodriguez, 583 U.S. 281, 286
(2018)). Courts have applied this rationale to Commerce Clause
challenges by interpreting State enactments to apply only within the
relevant State. See, e.g., Yamaha Motor Corp. v. Team Bozeman
Motorsports & Mont. Power Sports Dealers Ass'n, 2009 U.S. Dist.
LEXIS 147970, at *6 (D. Mont. Aug. 24, 2009) (interpreting Montana
regulation governing motorsports vehicle dealers to apply only to
dealers operating within the State).
---------------------------------------------------------------------------
Commenters cited to the EPA's approval of California's Warehouse
Indirect Source Rule as indicating that we understand the significant
role played by heavy-duty vehicles in emissions and NAAQS
attainment.\71\ But that observation does not support commenters'
conclusion that this SIP submission must be approved because it
contained ``necessary assurances'' that its implementation would not
violate Federal law. Unlike the regulation at issue in the cited prior
approval action, the HD I/M Regulation purports to regulate heavy-duty
vehicle owners and operators directly by requiring I/M activities that
must necessarily occur outside the State of California notwithstanding
the laws of the State in which they are registered or primarily
operate.
---------------------------------------------------------------------------
\71\ Comment ID EPA-R09-OAR-2025-0061-0040 (citing 89 FR 73568
(September 11, 2024)).
---------------------------------------------------------------------------
As articulated in the response to Comment 8 below, the EPA views
the burdens of the proposed approval and SIP on interstate commerce as
significant; such significant burdens outweigh the proposed benefits of
the proposed regulation and run afoul of the Dormant Commerce Clause
analysis. The compounding costs of testing, certification, and shipping
disruption based on the HD I/M Regulation's mandated downtime, and the
litany of administrative burdens across State lines, break down the
efficiency of interstate trade and would create a de facto national
program.\72\ As articulated by one commenter, it is hard to properly
estimate the ballooning costs of compliance due to the difficulties the
program unfairly imposes on out-of-state operators. One commenter
estimates that citations for non-compliance may not immediately be
received and by the time owners are aware of a citation ``potential
fines [may reach] up to $10,000 per day depending on the severity and
duration of the non-compliance.'' Such a risk will lead to fleet
closure, alteration, and trade breakdown, none of which was accounted
for in CARB's analysis.\73\ And contrary to some commenters'
assertions, there is no reason to believe that burdens would be lower
for out-of-state or out-of-country registered vehicles than for in-
state registered vehicles. Notwithstanding the limited exception for 5-
day pass throughs discussed elsewhere in this preamble, such owners and
operators will generally be forced to over comply, and access to CARB-
approved testing and compliance mechanisms and operators is necessarily
limited for owners and operators that primarily operate at significant
distance from California. As one commenter articulated: ``The program's
overreach will result in the potential for de facto regulation of out-
of-state rented or leased trucks across the country even though renting
and leasing companies have no control [over] whether their trucks'
routes include traveling into California. . . . CARB's HD I/M program
disproportionately affects out-of-state rental and leasing company
operations and finances . . . in clear violation of the Dormant
Commerce Clause.'' \74\
---------------------------------------------------------------------------
\72\ See generally Comment ID EPA-R09-OAR-2025-0061-0035.
\73\ See generally Comment ID EPA-R09-OAR-2025-0061-0036.
\74\ Id.
---------------------------------------------------------------------------
Comment 8: Dormant Commerce Clause--No Significant Burden
Several commenters argued that by their nature, the compliance
burdens associated with the HD I/M Regulation would not qualify as
substantial or undue burdens regardless of the degree of associated
benefits.
SCAQMD noted that several Supreme Court justices have signaled that
Pike balancing of benefits and burdens may be inappropriate in the case
of truly nondiscriminatory measures and that, regardless, requirements
to keep emission control equipment within the operating parameters
required by the HD I/M Regulation should not be considered a
significant burden, analogizing it to a requirement for tanker trucks
to maintain tanks in leak-free condition to prevent the escape of
hazardous materials.
An individual commenter questioned how testing for missing and
malfunctioning emissions control components that the commenter asserted
are already federally required can be considered an undue burden,
arguing that drivers who do not want to take the California test can
elect not to enter the State.
CAELP challenged the EPA's characterization of the HD I/M
Regulation's compliance costs as ``undoubtedly significant,'' arguing
that the costs cited are overstated and insufficiently analyzed and do
not consider the actual costs to individual operators, calculating that
the maximum daily cost to an individual vehicle under the most
conservative assumptions would be less than the toll fees assessed by
other States.
Response: As explained above, in National Pork Producers, ``six
Justices of [the] Court affirmatively retain[ed] the longstanding Pike
balancing test for analyzing Dormant Commerce Clause challenges to
state economic regulations.'' \75\ Under this balancing test, the
burdens felt across the nation outweigh the localized benefits to
California of more easily discharging its NAAQS attainment obligations
under Federal law. The preamble to our proposed rulemaking addresses
some of the costs associated with the HD I/M Regulation. Comments from
owners and operators in the trucking industry explained that the
burdens of applying the HD I/M Regulation to out-of-state and out-of-
country registered vehicles will be felt across the entire country. One
commenter pointed out that ``[b]y nature, trucks are mobile work units
that routinely traverse local, state, and international borders. Under
the HD I/M program, rented or leased trucks from outside California
could potentially enter the state without the knowledge of the rental
or leasing company since they are not in control of the vehicles'
routes.'' \76\ Thus, due to compliance costs and the heavy penalties
associated with unknowing and incidental violations, out-of-state
truckers will be forced to treat California's HD I/M Regulation as a
national standard regardless where they concentrate their business.
These risks and the attendant burdens are not ameliorated by the HD I/M
Regulation's limited pass through exception; rather, the potential for
out-of-state and out-of-country registered trucks to apply in advance
for a limited ``pass through'' exemption itself presents burdens, does
not comport with the nature of interstate trucking operations, and
admits that this aspect of the SIP submission is national in character
and unduly burdens truckers in other States and countries who would
have to track and amend their routes, dealings, and compliance
strategies in the event the program becomes federally enforceable.
---------------------------------------------------------------------------
\75\ 598 U.S. at 403 (Kavanaugh, J., concurring in part and
dissenting in part); see id. at 391 (Sotomayor, J., joined by Kagan,
J., concurring in part); id. at 394 (Roberts, C.J., joined by Alito,
Kavanaugh, and Jackson, JJ., concurring in part and dissenting in
part).
\76\ Comment ID EPA-R09-OAR-2025-0061-0036.
---------------------------------------------------------------------------
As illustrated by comments, the pass through exemption does not
ameliorate these concerns in practice as it requires a prior
application replete with information which may not be known to the out-
of-state and out-of-country operator in advance, imposes planning and
waiting obligations in the form of five business days before the grant
of prior permission by the CARB Executive, requires the physical
display of the granted pass in the vehicle at all times while
operating, and only
[[Page 5338]]
contemplates a window of five consecutive days per vehicle per year as
the maximum allowance, thus making small fleets incapable of using the
exemption regularly. Even large fleets could only use each truck in
their possession once per year under this program.\77\
---------------------------------------------------------------------------
\77\ Commenters pointed out that typical truck leases are
``dependent on flexible transportation contracts to manage variable
operations'' and that operators would struggle to plan around this
exception, as they typically lack certainty as to if and when a
truck would cross into California. Comment ID EPA-R09-OAR-2025-0061-
0036. Overcompliance would result to avoid ``potential fines
reaching up to $10,000 per day.'' Id.; see also Comment ID EPA-R09-
OAR-2025-0061-0023 (citing the impossibility of compliance); Comment
ID EPA-R09-OAR-2025-0061-0016 (a single owner operator would need to
buy another truck once the 5-day window was closed).
---------------------------------------------------------------------------
To the extent the HD I/M Regulation applies to out-of-state
vehicles that pass through or operate within California for almost any
length of time, its cost structure would also be imposed on other
States and regulated entities in those States. The EPA notes that many
heavy-duty vehicles covered by the regulations at issue are used for
purposes of interstate shipping, and that maintenance of those vehicles
could occur in any number of States, meaning the burdens of compliance
for certain trucking companies to operate in California or merely pass
through California will create an economic burden felt throughout the
United States. For vehicles merely passing through, the burdens will be
felt exclusively by other States. Even for vehicles that intentionally
operate within California (i.e., by shipping goods into the State),
these costs may make it prohibitively expensive for certain trucking
companies to operate in California, thereby creating an economic
rippling effect within and outside the State. ``This is particularly
burdensome for trucks registered out-of-state, which are considered
non-compliant unless they test prior to entering the state. These
vehicles might operate in California for only a few hours or days,
rather than for weeks or months, but must undergo testing to legally
enter the state.'' \78\ Finally, as explained elsewhere in this
preamble, the abstract comparison of benefits and costs in this context
should be informed by the nature of the benefits, i.e., allowing
California to obtain additional creditable emissions reductions to more
easily satisfy its NAAQS-attainment obligations under Federal law. In
essence, California is outsourcing the burdens of obtaining this
benefit to other States by extending the HD I/M Regulation to out-of-
state and out-of-country registered vehicles. That benefit is not a
legitimate use of the SIP program, and it does not comport with the
balance struck in the CAA between the roles of individual States and
the EPA's national role.
---------------------------------------------------------------------------
\78\ Comment ID EPA-R09-OAR-2025-0061-0047.
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Comment 9: Dormant Commerce Clause--Extraterritorial Reach
Several commenters challenged the EPA's specific characterizations
of extraterritorial effects of the HD I/M Regulation. Some commenters
asserted that HD I/M Regulation has no extraterritorial reach or effect
that would be relevant to the Commerce Clause analysis.
SCAQMD characterized the EPA's position as assuming that any
extraterritorial effect is forbidden, which the commenter argues is
inconsistent with applicable case law. The commenter cited a Ninth
Circuit decision allowing California to ban foie gras produced through
force-feeding practices, even though this conduct occurred wholly
outside of the State and thus impacted out-of-state conduct. In
contrast, the commenter argued, the HD I/M Regulation applies only to
conduct within California, does not require actions to be taken outside
of California, and has no effect of controlling purely out-of-state
actions.
Similarly, CCAEJ argued that under applicable case law, the HD I/M
Regulation does not violate the Commerce Clause merely based on its
extraterritorial reach, arguing that California has authority to apply
its laws to non-residents and out-of-state corporate entities. The
Coalition for Clean Air (CCA) described the HD I/M Regulation as an
exercise by California of the police power held by States to protect
their residents and noted that it does not dictate the activities of
any other State.
CAELP argued that the HD I/M Regulation does not regulate
extraterritorially because it does not require compliance from vehicles
that do not operate inside of California and does not impose any cost
on vehicles when they are outside of California. The commenter
analogized the EPA's concerns about the HD I/M Regulation's
extraterritorial reach to saying that California could not enforce its
criminal laws against residents of other States traveling through
California, or that California could not require out-of-state
corporations to register before doing business in the State.
CARB argued that the HD I/M Regulation does not regulate
extraterritorially because it does not directly regulate out-of-state
transactions by those with no connection to the State.
Response: The Commerce Clause vests the interstate regulatory
authority exclusively in Congress.\79\ The HD I/M Regulation's
extraterritorial application, which would effectively allow California
to set a nationwide regulatory standard, as explained in other
responses, would represent an abrogation of that unique Federal
authority. In addition, the Constitution vests the power over foreign
relations exclusively in the Federal Government. The HD I/M Regulation,
which applies to all vehicles operating in California, will
impermissibly burden vehicles registered in Canada and Mexico and the
other States. This is especially pressing in the case of Mexico, which
maintains a consulate in California frequented by diplomatic traffic.
As explained elsewhere in this preamble, these concerns are heightened
by the fact that Congress has legislated on the subject in the CAA by
providing that ``each State'' is responsible for developing a SIP to
implement the NAAQS ``within'' their State, authorizing the EPA to
establish national I/M requirements, and allowing for the waiver of
Federal preemption only when specific procedural and substantive
requirements are met. None of the comments described above presented a
valid analogy to the context here, and none can or did substitute for
the lack of necessary assurances in California's SIP submission.
---------------------------------------------------------------------------
\79\ See Gibbons v. Ogden, 22 U.S. (9 Wheat.) 1 (1824).
---------------------------------------------------------------------------
The EPA disagrees with commenters' assertions that the HD I/M
Regulation does not apply extraterritorially. By its terms, the
regulatory requirements apply to out-of-state and out-of-country
vehicles rather than only in-state registered vehicles, as is generally
the case in I/M regimes. This reach was intentional, as California
sought to obtain creditable emissions reductions not only from in-state
registered vehicles, but also from vehicles registered outside the
State. Compliance with the regulatory requirements necessarily
contemplates mandating out-of-state and out-of-country conduct, as
vehicles must be compliant with the regulation upon entering California
or risk substantial penalties. Thus, even before considering that full
approval of the SIP submission would make the HD I/M Regulation
enforceable outside California against any owner or operator based on
allegations that one or more vehicles traversed California, even
enforcement within the State of
[[Page 5339]]
California mandates behavior outside the State.
In an illustrative example of the flaws in these commenters' logic,
CAELP likens the EPA's concern to ``saying California cannot enforce
its criminal laws against another state's residents traveling through
California or that California . . . cannot require a Delaware
corporation to register with the California Secretary of State before
transacting business in Los Angeles.'' \80\ This argument fails to
recognize the impact of the EPA's approval of a SIP submission on
implementation of the SIP. Because approval makes SIPs federally
enforceable, including by citizen plaintiffs, the relevant analogy is
not to California enforcing its criminal laws against individuals
traversing the State, but to ``any person'' enforcing California's
criminal laws anywhere in the country so long as they allege that an
owner or operator's vehicle passed through California at one point in
time.\81\ The corporate registration analogy is also inapt because the
HD I/M Regulation does not contemplate requiring vehicle registration
in California as a predicate for being subject to the regulatory
requirements. Nor does this comment address the special considerations
due to instrumentalities of interstate commerce in the Commerce Clause
analysis.\82\ Thus, while ``the plurality in Pork Producers rejected
the argument that any `practical effect' of controlling the conduct of
commerce outside the state is barred'' \83\ it is also true that the HD
I/M Regulation, aimed directly at out-of-state instrumentalities--
``trucks, trains, and the like'' \84\--is likely barred by both Pike
and other relevant precedents.
---------------------------------------------------------------------------
\80\ Comment ID EPA-R09-OAR-2025-0061-0043.
\81\ See CAA sections 304(a) (authorizing ``any person'' to
commence a civil action for alleged violations), 302(e) (defining
``person'' as any ``individual, corporation, partnership,
association, State, municipality, political subdivision of a State''
as well as any arm of the Federal Government).
\82\ The case law cited by SCAQMD is equally inapplicable here.
Association des Eleveurs de Canard et d'Oies du Quebec v. Bonta, 33
F.4th 1107, 1118 (9th Cir. 2022), dealt with a State law banning the
practice of selling foie gras products in the State of California.
The Ninth Circuit dismissed claims asserting a variety of Commerce
Clause and preemption arguments because, in that instance, the State
law pertained only to what could be sold within California. Thus,
that case pertained to the regulation of in-state sales and did not
involve instrumentalities of interstate commerce. Additionally,
Rocky Mountain Farmers Union v. Corey, 730 F.3d 1070, 1103 (9th Cir.
2013), pertained to the impact of the State's ethanol standards
based on the full lifecycle of the production of ethanol fuels. The
Ninth Circuit found the law nondiscriminatory despite its practical
impact on out-of-state fuel production and remanded for analysis
under the Pike balancing test. Thus, this analysis does not pertain
to instrumentalities of commerce or the burdens a federally
empowered SIP would produce on out-of-state parties.
\83\ Comment ID EPA-R09-OAR-2025-0061-0043.
\84\ Nat'l Pork Producers, 598 U.S. at 379-80 & n.2 (majority
op.)
---------------------------------------------------------------------------
These commenters acknowledge that restrictions upon the
instrumentalities of commerce--like trucks--fall under the purview of
the Commerce Clause. And as emphasized above, regardless of the
existence of discriminatory intent, such restrictions upon
instrumentalities of commerce implicate special considerations in the
Commerce Clause analysis. As explained in the response to Comment 11,
the HD I/M Regulation also ``expresses a distinct point of view'' on
the politically charged issue of vehicle emissions reductions in
vehicles registered in and operating outside California and outside the
United States. This implicates the foreign affairs powers vested
exclusively in the Federal Government.\85\
---------------------------------------------------------------------------
\85\ United States v. Pink, 315 U.S. 203, 233, (1942) (``Power
over external affairs is not shared by the States; it is vested in
the national government exclusively.'').
---------------------------------------------------------------------------
Comment 10: Dormant Commerce Clause--Special Rules for
Instrumentalities of Interstate Transportation
SCAQMD acknowledged recent case law indicating that the Commerce
Clause applies with special force to regulations affecting
``instrumentalities of interstate transportation,'' but suggested that
relevant cases involved regulations that either had no benefit or
conflicted with requirements in other States.\86\ Similarly, CARB cited
case law suggesting that courts have invalidated facially neutral State
regulations on instrumentalities of interstate transportation only when
they were enacted at the instance of, and primarily benefit, in-state
interests. The commenters argued that these cases would not support
invalidating the HD I/M Regulation.
---------------------------------------------------------------------------
\86\ See generally Comment ID EPA-R09-OAR-2025-0061-0039, which
cites to Bibb v. Navajo Freight Lines, 369 U.S. 520 (1959), Kassel
v. Consolidated Freightways Corp. of Delaware, 450 U.S. 662 (1981),
and Raymond Motor Transportation, Inc., v. Rice, 434 U.S. 429
(1978), as examples of such cases. Commenter seeks to limit the Pike
test to circumstances like those in these cases in which the
invalidated State law had no major benefits to the local State. But
that is not what these cases say. Rather, they highlight the special
scrutiny applied to instrumentalities of interstate commerce like
heavy duty trucking. And in each instance, the State law was
invalidated despite involving arguably lower burdens than the HD I/M
Regulation at issue here.
---------------------------------------------------------------------------
Conversely, another commenter articulated: ``The program's
overreach will result in the potential for de facto regulation of out-
of-state rented or leased trucks across the country even though renting
and leasing companies have no control [over] whether their trucks'
routes include traveling into California. Since CARB's HD I/M program
disproportionately affects out-of-state rental and leasing company
operations and finances, the program . . . [is] in clear violation of
the Dormant Commerce Clause.'' \87\
---------------------------------------------------------------------------
\87\ Comment ID EPA-R09-OAR-2025-0061-0036.
---------------------------------------------------------------------------
Response: The Supreme Court noted in National Pork Producers that
``there exists a strong line of cases that originated before Pike in
which th[e] Court refused to enforce certain state regulations on
instrumentalities of interstate transportation--trucks, trains, and the
like.'' \88\ These cases and others demonstrate that State laws that
burden ``instrumentalities of interstate transportation'' warrant
special consideration under the Commerce Clause and may be invalid even
in the absence of discriminatory intent. Commenters did not offer a
plausible explanation that the HD I/M Regulation does not squarely
implicate this line of cases, or that California must be excused from
providing ``necessary assurances'' that implementing its SIP submittal
to out-of-state and out-of-country registered vehicles would not run
afoul of applicable law.
---------------------------------------------------------------------------
\88\ 598 U.S. at 379 n.2; see, e.g., Bibb, 359 U.S. at 523-30
(concerning a State law specifying certain mud flaps for trucks and
trailers); S. Pac. Co., 325 U.S. at 763-82 (addressing a State law
regarding the length of trains).
---------------------------------------------------------------------------
Contrary to these commenters' suggestions, full approval of the HD
I/M Regulation would necessarily generate conflict with I/M regimes
adopted in other States, including both existing programs and programs
that other States may seek to incorporate into their SIPs to obtain
creditable emissions reductions in the future. If made federally
enforceable by approval, ``any person'' could seek to enforce the HD I/
M Regulation by alleging a vehicle passed through California without
first complying with the regulation's requirements. As noted above,
this would create multiple and conflicting obligations with any State
that adopts a different I/M program and improperly pressure other
States to adopt an identical program into their SIP, with attendant
difficulties in disaggregating which emissions reductions could
properly be attributed to which State. Furthermore, the EPA disagrees
with commenters' assertions that the HD I/M Regulation involves local
benefits that distinguish a potential approval from the State laws at
issue in the cited cases. Here, the benefits adhere purely to
California by allowing the State to obtain credit for additional
emissions reductions beyond those that could be
[[Page 5340]]
credited by applying the HD I/M Regulation to in-state registered
vehicles. Those benefits are purely local, and they are not the type of
direct local benefits that courts have previously recognized as
legitimate ends. Nor are commenters correct that courts have taken
issue with State regulations burdening interstate commerce only when
there were no local benefits. Rather, the line of cases discussed above
recognizes the centrality of instrumentalities of interstate commerce
to the national market envisioned by the Commerce Clause and that local
benefits are more difficult to justify in the face of burdening such
instrumentalities.
Comment 11: Foreign Relations Powers
Several commenters challenged the EPA's proposed basis for partial
disapproval related to concerns that extraterritorial reach of the HD
I/M Regulation violates the foreign relation powers vested exclusively
in the Federal Government by the U.S. Constitution.
SCAQMD argued that the HD I/M Regulation does not have a prohibited
effect on foreign commerce, stating that there is no evidence of
discrimination or protectionism, and that California does not seek to
provide an advantage for in-state trucks. In response to the EPA's
concerns that HD I/M Regulation does not have an exception for
diplomatic activities by foreign nationals, the commenter argued that
such an exemption is unnecessary because diplomatic immunity is
afforded by Federal law external to the CAA or State regulations. The
commenter stated that cases interpreting ``dormant'' aspects of the
Foreign Commerce Clause focus on taxes and fees imposed on
instrumentalities of international commerce with legal tests that do
not apply in this case. The commenter argued that the HD I/M Regulation
does not violate the Foreign Commerce Clause as described in these
cases because it does not adversely impact the Federal Government's
ability to speak with one voice.
CCAEJ argued that the EPA has not identified or considered any
international treaties or conventions that would bear on California's
authority to adopt operational limitations on mobile sources under the
CAA. The commenter stated that the EPA failed to consider in particular
the United States-Mexico-Canada Agreement (USMCA), arguing that
California would retain its CAA authority to adopt the HD I/M
Regulation under provisions of the Agreement specifying that the
environmental law of the United States continues to apply. The
commenter included portions of the USMCA language as an attachment.
CAELP argued that the HD I/M Regulation comports with the foreign
affairs doctrine, arguing that HD I/M Regulation does not impinge upon
the Federal Government's conduct of foreign affairs. The commenter
disputed the EPA's characterization of potential conflicts with foreign
affairs authorities, arguing that the EPA's position would mean that
the Federal Government could block any State policy that it disfavored
simply because it might have some marginal effect on foreign entities.
According to the commenter, the Supreme Court has rejected this view,
finding a violation only where there is a direct impact on foreign
relations that could adversely affect the Federal Government's power to
deal with relevant problems. The commenter suggested that the EPA's
position could also raise separation of powers concerns to the extent
it intrudes into Congress' role in establishing the boundaries for
States' exercise of personal jurisdiction. The commenter stated that
the HD I/M Regulation is not expressly preempted because it does not
conflict with any treaties, conventions, executive agreements, or
express foreign policies. The commenter further stated that it is not
field preempted because it does not intrude on the Federal Government's
foreign affairs power under Ninth Circuit case law, because the EPA has
not offered any evidence that HD I/M Regulation diminishes the
President's power to speak and bargain effectively with other
countries, and because it addresses a traditional State responsibility
and is not intended to influence policy in other countries.
CARB argued that the EPA has not provided a reasoned basis for
partial disapproval related to foreign affairs preemption because it
does not cite any treaties or conventions or any potential impacts on
relevant Federal policy and because courts recognize conflict
preemption only in the face of a clear and definite foreign policy. The
commenter noted that the CAA relaxes State planning obligations in
areas affected by pollution from foreign countries but does not
distinguish State obligations to address emissions based on the
nationality of emissions sources. The commenter also argued that the HD
I/M Regulation does not unlawfully regulate in the field of foreign
affairs because it addresses a traditional State responsibility. The
commenter further argued that the HD I/M Regulation does not intrude on
the Federal Government's foreign affairs power because it does not
express a distinct political point of view on specific foreign policy
matters and does not require a highly politicized inquiry into the
conduct of a foreign nation, citing the Ninth Circuit's decision in
Movsesian v. Victoria Versicherung AG.\89\
---------------------------------------------------------------------------
\89\ 670 F.3d 1067 (9th Cir. 2012).
---------------------------------------------------------------------------
Response: The EPA disagrees with the commenters about the
compatibility of the HD I/M Regulation's application to out-of-country
vehicles with the Constitution's exclusive vestment of the foreign
relations power in the Federal Government. In the field of foreign
affairs, State regulations may be preempted by means of conflict
preemption or field preemption.\90\ Conflict preemption applies when
there is ``evidence of clear conflict'' with a Federal statute,
regulation, or policy.\91\ Field preemption requires a showing (1) that
the real purpose of a regulation falls outside the area of traditional
State responsibility and (2) that the HD I/M Regulation intrudes on the
foreign affairs power of the government.\92\
---------------------------------------------------------------------------
\90\ Gingery v. City of Glendale, 831 F.3d 1222, 1228 (9th Cir.
2016).
\91\ Am. Ins. Ass'n v. Garamendi, 539 U.S. 396, 421 (2003).
\92\ Movsesian, 670 F.3d at 1074-75.
---------------------------------------------------------------------------
As an initial matter, many of these commenters misstate the scope
of California's authority on the subject of mobile-source emissions.
CAA section 209 provides that States may not adopt or attempt to
enforce emissions standards for vehicles and engines, including
requirements related to, among other things, certification and
inspection, and the limited exceptions to express preemption are not
implicated here. CAA section 110 requires ``each State'' to adopt SIPs
that implement the NAAQS ``within'' their State, subject to review and
approval by the EPA for, among other things, whether the SIPs contain
necessary assurances that their implementation would not violate
Federal or State law. With respect to national standards, Congress
vested the authority to prescribe national emission standards for
vehicles and, among other things, I/M requirements for heavy duty
vehicles, exclusively with the EPA. For these reasons, the EPA
disagrees with commenters' characterizations that California has broad
authority to impose operational limits on mobile-source emissions, or
that regulating vehicles registered out-of-state and out-of-country is
a traditional State responsibility. Commenters again fail to
acknowledge the unprecedented quality of California's SIP submission in
this
[[Page 5341]]
respect, or to recognize the impact of a full approval that would
render the HD I/M Regulation federally enforceable by ``any person''
across the nation.\93\
---------------------------------------------------------------------------
\93\ Commenter's argument that the CAA does not distinguish
between the national origin of emissions in requiring States to
address emissions is similarly flawed. CAA section 110 requires
``each State'' to implement plans for attaining the NAAQS ``within''
their State and that plans, among other things, must include
necessary assurances that plan implementation would not violate
Federal or State law. Because obtaining creditable emissions
reductions by imposing I/M requirements on out-of-country registered
vehicles would violate Federal law for the reasons explained above,
the CAA does not permit States to use this strategy in their SIPs
without necessary assurances. CAA section 179B, which authorizes the
EPA to determine that a State plan would be sufficient to attain the
NAAQS ``but for emissions emanating from outside of the United
States,'' further supports the conclusion that the Federal
Government retains the authority to decide when and how to address
international emission impacts within the United States.
---------------------------------------------------------------------------
Given the structure of the statute, approving the HD I/M Regulation
in this respect would necessarily compromise the Federal Government's
ability to speak with one voice on the question of mobile-source
emissions. In all practical respects, California's HD I/M Regulation
would have the force and effect of Federal law, including as applied to
vehicles that enter the United States from foreign countries and pass
through California for any length of time, regardless of operations or
destination. Full approval of the HD I/M Regulation would, therefore,
both conflict with the CAA's division of responsibility between States
and the Federal Government and intrude into a field reserved for the
Federal Government by the Constitution.
While the control of pollution within a State's borders is a
traditional State responsibility, the HD I/M Regulation goes well
beyond this traditional ambit by its terms and would necessarily exceed
the ambit of traditional State responsibility if made federally
enforceable by approval into the SIP. In assessing whether a State law
falls within the ambit of traditional State authority, courts must
``[inquire] into the `real purpose' of the statute'' to determine
whether the regulatory imposition is merely ``garden variety'' or
exceptional.\94\ Here, the HD I/M Regulation departs from a garden
variety approach by imposing I/M requirements on out-of-state and out-
of-country registered vehicles that necessarily mandate behavior
outside the State of California.
---------------------------------------------------------------------------
\94\ Movsesian, 670 F.3d at 1074.
---------------------------------------------------------------------------
CARB cites to the Ninth Circuit's decision in Movsesian to support
its claim that the HD I/M Regulation is not covered by foreign affairs
preemption. There, the Ninth Circuit invalidated a California statute
granting State courts the authority to adjudicate Ottoman-era insurance
claims made by victims of the Armenian Genocide, finding that the law
did not address an area of traditional State responsibility and
intruded on the Federal foreign affairs power. Although insurance
regulation was a subject of traditional State regulation generally, the
statute was intentionally crafted to make California courts ``an
expeditious, inexpensive, and fair forum'' in which to resolve monetary
claims.\95\ Here, as in Movsesian, the HD I/M Regulation departs from a
``garden variety'' approach to intrastate pollution regulation by
requiring compliance from out-of-state and foreign vehicles to secure
to California the benefit of additional creditable emissions reductions
in furtherance of demonstrating attainment of the NAAQS.
---------------------------------------------------------------------------
\95\ Id. at 1067, 1076-77.
---------------------------------------------------------------------------
With respect to CARB's contention that the HD I/M Regulation avoids
intrusion on foreign affairs by not intruding into a politicized
inquiry into the conduct of another nation, the EPA disagrees. The HD
I/M Regulation ``expresses a distinct point of view'' on the
politically charged issue of emissions reductions--an issue that is
hotly debated, both in substance and regulatory response, within the
United States, Mexico, and Canada, and among the three nations, as well
as internationally.\96\ The HD I/M Regulation also implicates the
second prong of this test, which asks whether there has been an
intrusion on the Federal foreign affairs power. The HD I/M Regulation
``expresses a distinct point of view'' on the question by targeting
heavy duty vehicles as major emitters that should be subject to
increasingly stringent controls--a view with which the Federal
Government is entitled to disagree in negotiations with foreign
powers.\97\
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\96\ Id. at 1077 (noting that Turkey continued to express
``great concern'' over monetary claims arising out of the United
States and other countries).
\97\ Id. The premise of California's SIP submission is that
imposing more stringent requirements than required by Federal law
will generate creditable emissions reductions beyond those achieved
under Federal law.
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Comment 12: The EPA Should Not Decide Constitutional Issues
Several commenters suggested that the EPA should not disapprove a
SIP measure based on Constitutional issues that fall outside of its
area of expertise. Commenters argued that Pike balancing is more
appropriately handled by courts and questioned the EPA's role in
adjudicating these issues in advance of a judicial determination of the
Constitutional issues.
SCAQMD cited case law describing constitutional challenges as
falling outside of agency competence and expertise. The commenter also
cited a Supreme Court decision finding that the EPA could not consider
claims relating to the technological or economic infeasibility of a SIP
submittal and suggested that it would be contrary to this principle for
the EPA to introduce a similar analysis through an assessment of
Commerce Clause concerns.\98\
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\98\ See generally Comment ID EPA-R09-OAR-2025-0061-0039 (citing
Union Elec. v. EPA, 427 U.S. 246, 257-58 (1976)). This case does not
support the commenter's argument, however, because it addressed
whether the EPA may deny SIP measures limiting emissions from
stationary sources within the submitting State on grounds of
technological or economic infeasibility and did not involve the
concerns presented by California's novel attempt to obtain
creditable emissions reductions by extending its regulatory reason
to vehicles registered out-of-state and out-of-country.
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CARB argued that the EPA would not be entitled to deference in its
interpretation of the Commerce Clause or Foreign Affairs preemption.
Response: The EPA disagrees that the Agency lacks authority to
address whether California has provided ``necessary assurances'' that
implementation of its SIP submission in full would not violate Federal
or State law. As noted throughout this preamble, CAA section 110
expressly requires that SIP submissions satisfy all applicable
requirements of the statute, including the requirement to provide such
necessary assurances. We are not ``adjudicating'' constitutional claims
in this action, nor are we invoking deference to constitutional or
statutory interpretation. Rather, the EPA is exercising its authority
and obligation under CAA section 110 to assess the SIP submission
before it for compliance with statutory requirements.\99\
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\99\ As explained below, Loper Bright Enterprises v. Raimondo,
603 U.S. 369, 395 (2024), reinforces that agencies have the power to
act when such authority is expressly conferred by statute. That is
the case here, since CAA section 110(k) requires the EPA to approve
SIP submissions that meet the requirements of the CAA and,
conversely, does not authorize the EPA to approve aspects of SIP
submissions that do not meet the requirements of the CAA, including
the CAA section 110(a)(2)(E) requirement that the State provide
``necessary assurances'' that implementing the SIP would not violate
Federal or State law. Courts have long recognized that the EPA has
discretion in construing the undefined phrase ``necessary
assurances,'' and we are not relying here on an invocation of
deference to statutory interpretation.
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Commenters' assertions about the EPA's role in reviewing a SIP
submission would lead to untenable results. Absent the ability to
analyze
[[Page 5342]]
statutory and constitutional provisions (as elements of Federal law) as
applied to a SIP submission, the ``necessary assurances'' requirement
in CAA section 110(a)(2)(E) would be superfluous. Courts have
repeatedly recognized that the EPA has considerable discretion in
determining whether assurances provided, if any, are sufficient to
satisfy this statutory provision, and that determination requires
assessing the underlying legal concern. Under commenters' theory, the
EPA would be powerless to disapprove a SIP submission that
discriminated on the basis of race in violation of the Fifth Amendment
and applicable statutes so long as a State asserted that its submission
was lawful. But as CAELP conceded, in the past a violation of the Civil
Rights Act was not too speculative to deny the sufficiency of a State's
demonstration.\100\ CAELP further admitted that the ``EPA has a duty to
provide a reasoned judgment as to whether the state has provided
`necessary assurances,' but what assurances are `necessary' is left to
the EPA's discretion.'' \101\ In this case, California has not provided
necessary assurances that the aspects of the HD I/M Regulation which
seek to regulate instrumentalities of commerce outside the State would
not violate Federal law.
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\100\ Comment ID EPA-R09-OAR-2025-0061-0043. CAELP
mischaracterizes the EPA's action in various ways to claim that the
Agency lacks legal authority to disapprove a SIP in part for lack of
necessary assurances that its implementation would not violate
Federal or State law. As noted throughout this preamble, we are
acting pursuant to the CAA's command that a SIP must satisfy all
statutory requirements, including by providing such ``necessary
assurances.'' Indeed, CAELP admits that the ``EPA has some
discretion to determine the sufficiency of evidence that States must
provide to make ``necessary assurances.'' and appears to argue
instead that ``necessary assurances'' are only required when
potential illegality is ``well-defined in advance of the state's
submission.'' As an initial matter, we disagree that the relevant
legal issues discussed here are not ``well-defined''--Commerce
Clause jurisprudence is well established, and the division of
authority embodied in the CAA between States and the EPA (including
the limitations of the preemption waiver process in CAA sections 109
and 177, the obligation of ``each State'' to develop SIPs to attain
the NAAQS ``within'' the State, and the EPA's authority to
promulgate national I/M requirements) has been in place for decades.
Any novelty in this action arises from California's unprecedented
attempt to circumvent these requirements by imposing what amounts to
a nationwide I/M program that secures additional local benefits by
imposing burdens on other States and out-of-state and out-of-country
operators. Nothing in the text, structure, or logic of the statute
precludes the EPA from insisting on necessary assurances simply
because no State has ever attempted the same maneuver.
\101\ Comment ID EPA-R09-OAR-2025-0061-0043 (quoting El
Comit[eacute] para el Bienestar de Earlimart v. EPA, 786 F.3d 688,
701 (9th Cir. 2015), and citing NRDC, Project on Clean Air v. EPA,
478 F.2d 875, 890-91 (1st Cir. 1973)).
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Comment 13: The EPA Misapplies CAA 110(a)(2)(E)(i)
Several commenters challenged the EPA's proposed finding that
California has not provided necessary assurances under CAA section
110(a)(2)(E)(i) that the State has adequate authority to implement the
HD I/M Regulation consistent with Federal law. Commenters described
California's process for adopting the HD I/M Regulation, including the
State Legislature's enactment of legislation directing CARB to develop
and implement an HD I/M program and public hearings and stakeholder
meetings held during CARB's development of the HD I/M Regulation.
Commenters challenged the specific application of CAA section
110(a)(2)(E)(i) to the concerns identified in the proposed partial
disapproval, arguing that the State rulemaking record includes
sufficient analysis to support the State's authority to lawfully
implement the HD I/M Regulation. Commenters asserted that under CAA
section 110 and associated case law, the EPA is generally required to
approve SIP submittals that meet CAA requirements, including
requirements related to providing necessary assurances, and argued that
CAA section 110(a)(2)(E) in particular assigns the EPA a limited role
in determining whether a State has provided necessary assurances.
Commenters argued that this provision would not authorize the Agency to
decide novel legal issues or resolve speculative legal challenges, to
disapprove SIP submittals based on policy preferences, or to require
States to provide assurances that a submittal is not prohibited by
State law in other States or international law.
SCAQMD suggested that the EPA should allow the State an opportunity
to provide necessary assurances, arguing that any failure by the State
to submit a full legal argument does not mean that it lacks sufficient
justification for its position that the HD I/M Regulation is lawful.
The commenter asserted that the EPA is not required to make its own
determination that necessary assurances have been provided when there
is no reason that any would be necessary. The commenter cited EPA
statements in guidance suggesting that it is unusual for States to have
to make additional submittals related to authority once the EPA has
approved the State's infrastructure SIP and noted that the EPA
previously approved assurances of authority included in the State's
infrastructure SIP for the 2015 ozone standards.
CAELP noted that CAA section 182 requires some SIPs to include I/M
programs, which it describes as ``plainly valid plan components'' under
the CAA. The commenter distinguished Ninth Circuit case law finding the
EPA has discretion to determine the amount of evidence necessary to
provide ``necessary assurances'' under CAA section 110(a)(2)(E)(i),
noting that in that case the EPA had previously found a prima facie
violation of civil rights requirements well in advance of the State's
submission.
CARB pointed to specific portions of the Initial Statement of
Reasons (ISOR) and Final Statement of Reasons (FSOR) included in its
SIP submittal that it says provide the necessary assurances required
under CAA section 110(a)(2)(E)(i), and noted that the State Office of
Administrative Law's approval of the HD I/M Regulation included a
separate review to ensure consistency with State and Federal law. The
commenter argued that the legislative history of the 1990 amendments to
CAA section 110(a)(2)(E)(i) shows that Congress ratified early
interpretations of the provision by the EPA and reviewing courts that
suggest a more modest demonstration that would not require States to
analyze potential legal challenges. The commenter asserted that the EPA
was changing its position relative to previous actions in which the
Agency provided that a State is not required to ``demonstrate'' that a
SIP submittal is not prohibited by State or Federal law, but is instead
is required only to provide ``necessary assurances'' to that effect,
and that a general assurance of certification is sufficient.
Commenters also cited cases to the effect that Constitutional
claims fall ``outside the [Agency's] competence and expertise.'' \102\
For example, SCAQMD states that ``While there are some cases where
Federal agencies decline to act on the grounds of unconstitutionality,
these generally involve situations where the agency is deciding whether
to implement its own statute, not where they declare a state or local
law to be unconstitutional.''
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\102\ Comment ID EPA-R09-OAR-2025-0061-0039 (quoting Free Enter.
Fund v. Pub. Co. Acct. Oversight Bd., 561 U.S. 477, 491 (2010)). We
note that the quoted excerpt is taken out of context. The Supreme
Court was describing why, under the legal standard for determining
whether claims must be presented to an agency in the first instance,
the relevant statute did not deprive district courts of jurisdiction
to consider constitutional challenges to the structure of the PCAOB
(specifically, the two layers of removal protection for the Board's
members).
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Response: As explained above, the EPA has a statutory obligation
under CAA section 110(a)(3)(E) to determine
[[Page 5343]]
whether a State has provided ``necessary assurances'' that
implementation of its SIP submission would not violate State or Federal
law. Courts have recognizing that this language necessarily provides
the Agency with discretion to determine what assurances are
``necessary'' relative to the legal issues presented. Approval of a SIP
gives the submission the imprimatur of Federal law, and renders it
federally enforceable. There can be no side-stepping of the task of
evaluating whether a State has provided necessary assurances that its
SIP will not conflict with Federal law.\103\ It is misleading to state
that EPA is declaring anything to be unconstitutional. Rather than
adjudicating constitutional claims, as commenters assert, the EPA is
acting pursuant to CAA requirements to deny a full approval based on
substantial and valid concerns that the assurances provided are
inadequate. There is a circularity of reasoning in the comments in
which commenters focus on the State's authority under State law to
promulgate a regulation. Commenters then pivot to saying that this
satisfies the Federal assurances requirement of the CAA. As stated
above, ``Commenters noted that under CAA section 110 and associated
caselaw the EPA is generally required to approve SIP submittals that
meet CAA requirements, including requirements related to providing
necessary assurances.'' But this statement clearly includes the
requirement for necessary assurances. There is nothing novel about the
EPA evaluating whether the proposed SIP violates the Federal
Constitution. Unlike prior CARB regulations adopted by other States,
the HD I/M Regulation submitted for review would apply to vehicles
registered out-of-state and out-of-country that traverse within the
State of California for virtually any minimal length of time or perhaps
not at all. The costs may make it prohibitively expensive for certain
trucking companies to operate in California, but even if companies do
not intentionally operate there, but rather pass through, they would be
impacted by the economic burden created nationwide by the regulation.
``This is particularly burdensome for trucks registered out-of-state,
which are considered non-compliant unless they test prior to entering
the state. These vehicles might operate in California for only a few
hours or days, rather than for weeks or months, but must undergo
testing to legally enter the state.'' \104\ And as some commenters have
pointed out, the functional impact goes farther to reaching operators
who never enter California at all. Comments from truckers and industry
representatives reveal that the force of these regulations will be felt
across the entire country. One commenter pointed out that ``[b]y
nature, trucks are mobile work units that routinely traverse local,
state, and international borders. Under the HD I/M program, rented or
leased trucks from outside California could potentially enter the state
without the knowledge of the rental or leasing company since they are
not in control of the vehicles' routes.'' \105\
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\103\ A violation of the Federal Constitution falls well within
the bounds of that requirement, thereby obligating the EPA to assess
whether the State has provided necessary assurances. As noted above,
the EPA has previously applied this statutory requirement to assess
whether the State provided ``necessary assurances'' that plan
implementation would not violate the Civil Rights Act. See Comment
ID EPA-R09-OAR-2025-0061-0043 (citing El Comit[eacute] para el
Bienestar de Earlimart v. EPA, 786 F.3d 688, 700 (9th Cir. 2015)).
\104\ Comment ID EPA-R09-OAR-2025-0061-0039 (citing In re Aiken
Cnty., 725 F.3d 255, 259 (D.C. Cir. 2013)). The commenter cites to
Aiken County with the parenthetical ``describing authority,'' but it
is not clear why the commenter believes this citation supports its
argument. In that case, the D.C. Circuit reasoned that agencies must
abide by statutory requirements unless there are no congressional
appropriations available or they have a constitutional objection to
implementing the statute and could not simply decline to implement a
licensing process. Here, we are acting pursuant to express statutory
requirements by partially disapproving a SIP on the ground that the
submitting State did not provide the ``necessary assurances''
required for an approval. It is worth noting the complete
inapplicability of this case to this circumstance. In Aiken the
agency in question refused to comply with a statutory mandate to
issue a decision in a licensing process. The lack of any decision
was the issue in that case, which has no comparison to this SIP
decision.
\105\ Comment ID EPA-R09-OAR-2025-0061-0036.
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Thus, due to the risks of compliance costs and penalties, out-of-
state truckers will be forced to treat California's HD I/M Regulation
as a national standard regardless of where they concentrate their
business or if they even enter the State. We disagree with commenters'
assertions that the CAA's ``necessary assurances'' requirement amounts
to a box-checking exercise. The analysis presented in this preamble is
novel only to the extent that CARB's submission is unprecedented in
scope. The State's legislative and rulemaking record does not
adequately address this concern, including the general review conducted
by the State's administrative law office. California appeared
throughout to take an overly broad view of its authority and not to
recognize the problem of its I/M requirements mandating behavior
outside the State, particularly if the SIP submission were to be
approved and therefore made federally enforceable. For similar reasons,
we disagree that general assurances provided in California's
infrastructure SIP some years ago have any relevance to this
submission, particularly given the novel provisions at issue in this
partial disapproval.
With respect to comments attempting to distinguish case law
interpreting CAA section 110(a)(2)(E), including through legislative
history, we disagree that this situation warrants a particularly
relaxed approach to the ``necessary assurances'' requirement. Courts
have recognized that CAA section 110(a)(2)(E) requires the EPA to
evaluate assurances provided by the submitting State, if any, against
the relevant legal standard and any factual submissions before the
Agency.\106\ Nor do we agree that legislative history that commenters
assert ``ratified'' a more permissive approach prior to the 1990
amendments controls over the plain text of the statute, which courts
have since construed as conferring discretion in case-by-case
application.
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\106\ See, e.g., El Comit[eacute] para el Bienestar, 786 F.3d at
700-01 (stating that the EPA ``has a duty to provide a reasoned
judgment as to whether the state has provided `necessary assurances'
'' and holding that the Agency reasonably exercised its
``discretion'' in evaluating comment submissions to determine
whether there was ``any connection between the proposed rules and a
potential disparate impact'' in the civil rights context).
---------------------------------------------------------------------------
With respect to commenters citation to CAA section 182, this
provision undermines, rather than supports, commenters' positions that
California has broad authority to mandate I/M requirements, including
for out-of-state and out-of-country vehicles, and that California
provided necessary assurances that implementing that aspect of the SIP
submission would comply with Federal law. As discussed previously, CAA
section 110 requires ``each State'' to develop plans for implementing
and maintaining the NAAQS ``within'' their State. CAA section 182
builds on this general SIP provision by providing for sequenced
nonattainment classifications for particular States that fail to attain
by the applicable deadline. These classifications--marginal, moderate,
serious, severe, and extreme--are specific to each State and to each
area within a State. States that immediately attain the NAAQS may never
be designated nonattainment, and even States that fail to attain may
never be designated at higher nonattainment levels. The structure of
this provision demonstrates that the minimum I/M requirements imposed
at particular nonattainment classifications are intended to be State-
specific, as the mandatory I/M requirement for serious nonattainment
areas, for example, are
[[Page 5344]]
triggered only when an area is classified as serious nonattainment and
are not required for areas classified attainment or a lower form of
nonattainment.\107\ By effectively imposing the HD I/M Regulation on
owners and operators based in and servicing areas around the country
regardless of classification, California's SIP submission disrupts the
detailed scheme Congress enacted to incentivize attainment through
area-specific measures that increase in stringency in the face of
prolonged nonattainment.
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\107\ See CAA section 182(c)(3).
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Finally, one comment asserted that EPA has changed its position
regarding the ``necessary assurances'' requirement for SIP submissions
without an adequate explanation.\108\ That is inaccurate. As noted at
proposal, this situation presents a novel question on which the EPA has
never had to develop a formal position. The Agency proposed a view in
response to California's SIP submission and sought public comment. With
respect to CAA section 110(a)(2)(E) more generally, the EPA previously
asserted that it cannot approve a SIP when the State has not provided
necessary assurances that the SIP could be implemented consistent with
Federal and State law.\109\
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\108\ Comment ID EPA-R09-OAR-2025-0061-0045.
\109\ See 87 FR 60494, 60529 (October 5, 2022) (``EPA [has]
ample discretion in deciding what assurances are `necessary' '')
(citing BCAA Appeal Grp., 355 F.3d at 830 n.11); id. at 60529 n.276
(citing El Comit[eacute] para el Bienestar, 786 F.3d at 701).
---------------------------------------------------------------------------
The commenter cited BCCA Appeal Group, which discussed the EPA's
evaluation of a State's legal authority under State law to carry out a
SIP. There, the court rejected a petitioner's argument that the EPA
should have conducted an ``extremely burdensome'' evaluation of State
law when it had no reason to doubt the assurances provided by the
State.\110\ Here, in contrast, the EPA is determining that California
failed to provide necessary assurances that implementing the out-of-
state elements of the HD I/M Regulation is consistent with Federal law,
namely, the Commerce Clause and the CAA. The commenter also cites to
the Fifth Circuit's statement in BCAA Appeal Group, referring to a
prior EPA SIP action, that ``EPA is entitled to rely on a state's
certification.'' \111\ But the EPA made clear in prior actions that
``Congress has left to the Administrator's sound discretion
determination of what assurances are `necessary' under CAA section
110(a)(2)(E)(i).'' \112\ On the contrary, as other commenters noted,
the ``EPA has a duty to provide a reasoned judgment as to whether the
state has provided `necessary assurances,' but what assurances are
`necessary' is left to the EPA's discretion.'' \113\ Just as it may be
reasonable under particular circumstances to rely on a State's
assurances, particularly in a construction of applicable State law, so
also is it reasonable in the circumstances presented here to conclude
that a State has not provided necessary assurances, particularly in
construing Federal law in the context of a novel and substantial
assertion of State authority.
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\110\ 355 F.3d at 830 n.11; see also id. at 845 (collecting
authorities holding that the EPA has discretion to determine what
assurances are ``necessary'').
\111\ Comment ID EPA-OAR-R09-2025-0061-0045 (citing BCAA Appeal
Grp., 355 F.3d at 830 n.11); see also 87 FR 61249, 61257 (October
11, 2022)).
\112\ 87 FR 61249, 61259 n.85 (quoting NRDC, 478 F.2d at 884,
and citing BCCA Appeal Grp., 355 F.3d at 844-47).
\113\ Comment ID EPA-R09-OAR-2025-0061-0043 (quoting El
Comit[eacute] para el Bienestar, 786 F.3d at 701 (citing NRDC, 478
F.2d at 890-91)).
---------------------------------------------------------------------------
Although the EPA has not changed its position on this question,
under FCC v. Fox Television Stations, Inc., 556 U.S. 502, 515 (2009),
an agency may change its position by providing a reasoned explanation
for the change that acknowledges the shift and accounts for legitimate
reliance interests. Multiple circuits have held that the phrase
``necessary assurances'' in CAA section 110 is a broad term which
provides the Agency significant discretion in evaluating what is
necessary in each instance.\114\ These cases were not based on
deference to the Agency's statutory interpretation. Rather, consistent
with the Supreme Court's decision in Loper Bright, the statutory
language itself confers authority to exercise reasoned judgment.\115\
Given the technical and case-specific nature of the SIP development and
review process, the best reading of the phrase ``necessary assurances''
confers flexibility to the EPA in evaluating what assurances are
required. Contrary to assertions made by one commenter, a ``general
assurance or certification'' which reduces the Federal role to a mere
rubber stamp would not be acceptable for fulfilling the EPA's statutory
obligation to ensure that implementation of a SIP would not violate
Federal law. Commenters did not present concrete reliance interests
that were not considered during this rulemaking and could warrant a
different outcome. To the extent commenters construe purported benefits
associated with a full approval of the HD I/M Regulation, however, we
cannot agree that any such reliance is reasonable or legitimate. As
noted previously, the out-of-state aspects of the HD I/M Regulation are
novel, and the interests of California and commenters supporting
California's position in demonstrating additional creditable emissions
reductions for NAAQS attainment purposes are not sufficient to conclude
that the State provided ``necessary assurances'' that implementing the
SIP would not violate Federal law.
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\114\ El Comit[eacute] para el Bienestar, 786 F.3d at 701
(citing NRDC, 478 F.2d at 890-91); BCCA Appeal Grp., 355 F.3d at 830
n.11.
\115\ 603 U.S. at 395.
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Finally, the EPA notes that its actions are constrained by Federal
law separate and apart from the requirements of CAA section 110. It is
axiomatic that Federal agencies may not take actions that violate the
Constitution.\116\ Under the circumstances here, approving the SIP
submission in full would give the imprimatur of Federal law (and make
federally enforceable) a regulatory scheme that appears inconsistent
with the allocation of authority set out in the Commerce Clause.
Furthermore, the SIP submission's out-of-state applicability is
inconsistent with CAA section 110, which charges ``each State'' to
develop requirements for ``such State'' to achieve compliance with the
NAAQS and, as discussed above, is consistent more broadly with the
Act's division of Federal and State authority. This risks undermining
regulatory consistency nationwide, and risks upsetting the entire NAAQS
structure whereby each State plans and regulates as appropriate to
comply with the requirements of the CAA.
---------------------------------------------------------------------------
\116\ See, e.g., Aiken Cnty., 725 F.3d at 259 (summarizing
relevant constitutional principles).
---------------------------------------------------------------------------
Comment 14: No Conflict With Other SIPs
Several commenters challenged the EPA's proposed basis for partial
disapproval related to substantial concerns that approving the
extraterritorial reach of the HD I/M Regulation could interfere with
attainment and reasonable further progress (RFP) in other areas and
with implementation of approved SIPs for other States. Commenters noted
that the EPA had not identified any specific conflicting requirements
in other States and argued that any such conflict is unlikely since
vehicles subject to multiple State requirements could comply with the
more stringent requirements.
UCS argued that the EPA's concerns about conflicts between the HD
I/M Regulation and other State SIPs is based on ``flawed logic,''
because the HD I/M
[[Page 5345]]
Regulation does not require any action to occur in other States,
because the HD I/M Regulation applies only to vehicles that operate in
California and enforcement would occur only within California, and
because the HD I/M Regulation does not prevent out-of-state trucks
subject to the HD I/M Regulation from complying with their home State's
regulations. The commenter also highlights that it is a widespread
practice for commercial vehicles to be domiciled and to commonly
operate outside their State of registration, and suggests that it would
be unreasonable for an out-of-state operator of vehicles in California
to conduct its business without regard for California public health
issues and regulations. The commenter suggested that as an alternative
to partial disapproval, the EPA should facilitate a shared agreement
among California and other States to allow vehicles to qualify as
compliant if they have previously been tested under more stringent
emissions inspection standards in another State.
CARB argued that the EPA's concerns about potential conflicts with
laws in other States are too vague and speculative to justify partial
disapproval, because the Agency has not identified any specific State
programs that would conflict with the HD I/M Regulation. The commenter
cited a Ninth Circuit decision upholding a Utah vehicle maintenance
program that applied to some vehicles registered in other States as
allowing non-uniformity of State in-use vehicle rules.
Some commenters provided details about other State HD I/M programs.
CCAEJ pointed to statements in the proposed rulemaking noting that no
other States implement HD I/M provisions as part of their SIPs. UCS
cited information indicating that as of 2024, 17 States maintained some
form of statewide or regional inspection requirements for heavy-duty
vehicles.
Response: As explained in the response to Comment 8 and elsewhere
in this preamble, commenters' claim that implementation of the HD I/M
Regulation would not interfere with or contravene any other States'
SIPs is contradicted by the concerns expressed and by the nature of the
trucking industry and the burden that the HD I/M Regulation would place
upon out-of-state-registered vehicles and fleets. Particularly if made
federally enforceable, any person could attempt to bring an action
alleging that a vehicle passed through California without first
complying with the HD I/M Regulation, no matter where that vehicle is
registered, receives maintenance, and generally operates. Owners and
operators would be forced to comply with California's HD I/M Regulation
even if their State of registration imposes different I/M requirements.
And other States would face limited options when seeking to use their
own I/M programs to obtain creditable emissions reductions as part of
SIPs submitted pursuant to CAA section 110. Thus, due to compliance
costs and the risk of substantial penalties, out-of-state truckers will
be forced to treat California's HD I/M Regulation as a national
standard regardless of where they concentrate their business, and the
nationwide reach of California's HD I/M Regulation could restrict the
ability of other States to fulfill their statutory obligation to
provide for a plan to maintain the NAAQS ``within'' their State.
Also, as explained elsewhere in this preamble, California's SIP
submission seeks to remedy local nonattainment by extending the State's
regulatory reach to vehicles registered in other States, and even other
countries, that happen to traverse the State. This result is not
contemplated or authorized by CAA section 110, which requires ``each
State'' to implement the NAAQS ``within such State,'' and does not fall
within any of the exceptional provisions of the Act that contemplate
one State reaching into another State in pursuit of air quality
improvements within its own borders. This is not a lawful use of the
CAA's SIP provisions, which instruct each State to adopt appropriate
controls for that State and prohibit the approval of SIPs not supported
by ``necessary assurances'' of legality under Federal and State law.
California may adopt and seek approval of a broad range of strategies
to promote NAAQS attainment within the State, including by adopting
additional measures for vehicles registered within the State. But it
cannot (at minimum, without providing necessary assurances) outsource
the costs of local attainment to out-of-state and out-of-country
vehicle owners and operators through a regulation that would, if
approved, become federally enforceable throughout the country in lieu
of adopting additional controls for vehicles registered within the
State. Some States have HD I/M provisions that differ from California's
in material respects, but none of these have been approved into
SIPs.\117\ If approved into the SIP in all respects, California's HD I/
M Regulation would be federally enforceable to the same extent as other
State I/M regulations, including any that may be approved by the EPA in
the future pursuant to CAA section 110. The result would be multiple
conflicting sources of obligations that are enforceable both within the
respective States and federally under the CAA.
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\117\ See 6 NYCRR subpart 217-5 (New York Heavy Duty Inspection
and Maintenance Program); N.J.A.C. 7:27-14 (New Jersey Control and
Prohibition of Air Pollution); ORS 815.200-215 (Oregon motor vehicle
pollution control); see also Comment ID EPA-OAR-2025-0061-0047
(``Existing HD I/M programs, or new programs adopted in the future,
may not all have identical requirements, but any discrepancies are
likely to have an immeasurable impact on air quality outcomes
provided they are target high-emitting vehicles. Greater assurances
are needed that the emissions benefits from these separate programs
are properly accounted for and do not overlap.'').
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Comment 15: Partial Disapproval Is Otherwise Arbitrary and Capricious
Several commenters argued that the EPA's proposed partial
disapproval is arbitrary and capricious or otherwise not in accordance
with law, for reasons addressed in other comments and based on
additional claimed deficiencies, including that the proposal fails to
consider relevant legal and factual issues, fails to include sufficient
analysis or support, and is based on incorrect assumptions.
Among other claims, commenters asserted that the proposal includes
an insufficient legal and factual basis to establish violations of the
Commerce Clause or other constitutional provisions, fails to consider
benefits associated with the HD I/M Regulation either separately or in
balance with costs, and fails to acknowledge or explain the EPA's
purported change in policy regarding the nature of necessary assurances
that a State must provide (including in the context of the Dormant
Commerce Clause). Some commenters suggested that the EPA had not
provided a ``reasoned judgment'' to support the proposed partial
disapproval. Certain commenters also suggested that the proposed
disapproval is pretextual because it is based on considerations other
than those described in the proposal, including considerations not
authorized by the CAA. These commenters pointed to language in an EPA
press release announcing the proposal, which described the HD I/M
Regulation as related to climate ideology rather than reduction of
criteria pollutants, noting that the HD I/M Regulation is not aimed at
reducing greenhouse gases and is not included in the State's plans
related to climate change. CARB stated that this language suggests the
EPA is acting out of unrelated hostility to California over its other
regulatory efforts.
Response: The EPA disagrees that partial disapproval of the HD I/M
[[Page 5346]]
Regulation is inappropriate for the reasons suggested by
commenters.\118\ To the extent commenters have suggested that
additional discussion is needed to support the proposed rulemaking, we
note additional analysis included in this document, which describes the
basis for our final action, including in response to issues raised by
commenters. In compliance with all statutory and administrative
requirements, the EPA provided notice in the Federal Register and an
opportunity for public comment on a proposed rulemaking seeking either
to partially approve and partially disapprove or to fully approve this
SIP revision. That opportunity for public input generated a robust
response, and we disagree with commenters to the extent they assert
that the opportunity for public input during this rulemaking was
insufficient.
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\118\ With respect to commenters' assertions of pretext based on
an EPA press release, we disagree with the suggestion that this
action was motivated by reasoning related to other CARB regulatory
efforts addressing global climate change concerns. As explained at
proposal and in this final rule, the EPA is disapproving the SIP
submission in part because California failed to provide the required
necessary assurances that implementation of the HD I/M Regulation
would, if approved and made enforceable nationwide, be consistent
with Federal law. Notably, we are approving the SIP submission in
part to the extent it complies with the statute and does not raise
the same problem with respect to necessary assurances and Federal
law. Commenters are taking the press release out of context to avoid
grappling with the rationale and basis for decision included in the
proposed rule.
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The EPA proposed partial approval and partial disapproval based
upon California's failure to provide the ``necessary assurances'' that
its SIP submission could be implemented consistent with Federal law.
The EPA also asked for comment related to the concern that the HD I/M
Regulation could also interfere with other applicable requirements of
the Act concerning attainment and RFP, as well as the implementation of
SIPs submitted by other States and approved by the EPA.
Many comments favoring partial disapproval were received from
farmers, independent truckers, small trucking businesses, and national
trucking organizations. These groups posited that the HD I/M Regulation
violates the Commerce Clause by imposing serious burdens upon
interstate commerce. Through the intake and review of comments
submitted, the EPA was informed by myriad concerned parties that while
owners of heavy-duty vehicles registered in and operating in California
must register with CARB, submit reports on the functionality of their
emissions control systems to CARB by way of CARB-certified inspectors,
and obtain a compliance certificate to be presented during CARB-led
inspections, the HD I/M Regulation also applies to all non-gasoline
combustion vehicles above 14,000 lbs that pass through California.
Unlike prior CARB regulations and similar regulations adopted by other
States, the HD I/M Regulation submitted for review would apply to
vehicles registered out-of-state and out-of-country that traverse the
State of California for virtually any length of time. It has been the
consistent policy of the EPA to evaluate the necessary assurances
provided by the State for compliance with CAA section 110. As admitted
by multiple commenters and in case law, the ``EPA has a duty to provide
a reasoned judgment as to whether the state has provided `necessary
assurances.' '' \119\ A submission cannot be approved without such
assurances, and the EPA cannot simply sidestep such Federal
constitutional issues based on assertions that California has or should
have broad authority to regulate nationwide in pursuit of purported
benefits. The EPA has both the discretion and a statutory obligation to
review such a submission, weighing the necessary assurances provided,
if any, alongside relevant information and the applicable legal
standard--here, including a review of the purposes of the regulation,
its projected costs and purported benefits, and case law bearing on the
proper interpretation of relevant CAA provisions and the Commerce
Clause. Based on diligent review of the comments, legal issues, and
information associated with the proposed SIP, the EPA made a reasonable
decision and reasonably explained that decision as required by the
Clean Air Act and relevant sources of administrative law, including the
Administrative Procedure Act.
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\119\ Comment ID EPA-R09-OAR-2025-0061-0043 (quoting El
Comit[eacute] para el Bienestar, 786 F.3d at 701, and citing NRDC,
478 F.2d at 890-91).
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C. Other Comments
Comment 16: General Objections to HD I/M Regulation and Other CARB
Actions
Numerous commenters expressed general disapproval of the HD I/M
Regulation and other CARB regulations. Many of these commenters
highlighted concerns about the costs and other burdens associated with
compliance with CARB's motor vehicle regulations, with some questioning
whether HD I/M Regulations were cost-efficient generally, effective for
reducing air pollution, or otherwise necessary. Several commenters
described experiences as members of the regulated community, including
personal hardships they have faced or anticipate facing as a result of
CARB regulations. Some criticized CARB initiatives related to climate
change.
Response: We understand many of these comments to be generally
supportive of the EPA's proposed partial disapproval, including those
objecting to the HD I/M Regulation's application to out-of-state and
out-of-country vehicles. For further treatment of comments in support
of the partial disapproval alternative, please see our responses to
Comments 1 through 4. Comments related to other CARB regulations,
including other regulations applicable to heavy-duty diesel vehicles
and measures to address climate change, are outside the scope of this
action. As noted in our response to Comment 17, comments regarding
specific design and function of the HD I/M Regulation are also outside
the scope of this action. However, we note that the partial disapproval
finalized in this action does not reflect an analysis of CARB's
regulations generally or the costs of the HD I/M Regulation solely with
respect vehicles registered within the State. Additional CARB
regulations are out of scope for this final action, and we are
approving the HD I/M Regulation to the extent applicable to vehicles
registered within the State. Unless provided otherwise by the CAA,
States generally have substantial discretion to develop and implement
plans, subject to EPA review and approval, to attain and maintain the
NAAQS.
Comment 17: Suggested Revisions to the HD I/M Regulation
Several commenters raised concerns regarding specific programmatic
design elements of the HD I/M Regulation and other measures, including
their application to vehicles registered outside of California,
exemptions or flexibilities for specific classes of vehicles, and
issues related to HD I/M Regulation's testing and reporting obligations
and other enforcement mechanisms.
Response: These comments fall outside the scope of this final
action. Although we are disapproving the HD I/M Regulation with respect
to vehicles registered outside of California, the EPA cannot amend
State rules that comply with CAA requirements through the SIP review
process. As noted previously, States generally have substantial
discretion to develop and implement plans, subject to EPA review and
approval, to attain and maintain the NAAQS. Thus, we are approving the
HD I/M Regulation to the extent it applies to vehicles registered
within the State of
[[Page 5347]]
California as consistent with applicable requirements of the CAA.
Comment 18: General Support for HD I/M Programs
The Manufacturers of Emission Controls Association (MECA) expressed
general support for HD I/M programs as a tool to ensure vehicles
operate as designed throughout their useful lives, and particular
support for California's HD I/M Regulation as an example for other
States. The commenter cited the effectiveness of diesel oxidation
catalysts, diesel particulate filters, and selective catalytic
reduction emissions control technologies, and noted the importance of
I/M requirements for sustaining the benefits of these technologies over
a vehicle's lifetime. The commenter highlighted the role of I/M as a
deterrent to known high-emission operations and tampering, as a
mechanism for ensuring a level playing field across the trucking
industry, and as a proactive monitoring tool to identify fleet
maintenance needs.
Response: The EPA acknowledges the general benefits of regular I/M
for vehicles and emission control, including the role of State
regulatory programs applicable to in-state registered vehicles. For
this reason, among others, we are approving the HD I/M Regulation as it
applies to California-registered vehicles. See our response to Comment
6 for additional responses related to our consideration of general
benefits of the HD I/M Regulation.
Comment 19: Requests for Additional Analysis
An anonymous commenter suggested that the EPA provide additional
discussion and documentation on several topics. The commenter asked the
EPA to provide more detailed criteria or examples regarding what
constitutes acceptable State ``assurances'' under CAA section
110(a)(2)(E)(i). The commenter requested additional clarification
regarding the effect of finalizing a partial disapproval, including
issues relating to the timing for approved provisions to take effect,
the impacts to California attainment planning efforts, and implications
for future SIP flexibility. The commenter also asked the EPA to
evaluate whether Federal programs could complement State efforts to
prevent emissions leakage and to require California to provide reports
related to compliance and enforcement and to recommend that the State
incorporate environmental justice screening into its enforcement
activities.
Response: Please see our responses to other comments and other
portions of this preamble for additional discussion of CAA section
110(a)(2)(E)(i) and the effects of partial disapproval of the HD I/M
Regulation. Our partial approval and partial disapproval will become
effective 30 days from the date of publication of this final action in
the Federal Register. We disagree with the commenter that other
additional evaluation or documentation is necessary to support this
action, but note that the Agency has provided guidance regarding SIP
submissions in a number of respects and remains committed to working
with States to assist in developing approvable submissions that meet
the requirements and objectives of the CAA. With respect to the
question whether Federal programs complement State efforts to prevent
emissions leakage, we note that the EPA has adopted inspection and
maintenance requirements in several contexts and issued guidance on I/M
programs generally in response to the 1990 CAA Amendments. Finally,
with respect to compliance and enforcement, our approval of the HD I/M
Regulation to the extent it applies to in-state registered vehicles
reflects a determination that California's SIP includes sufficient
reporting, compliance, and enforcement mechanisms to satisfy applicable
CAA requirements. The statute does not require, or authorize the EPA to
require, environmental justice screening as part of that demonstration.
Comment 20: Partial Conditional Approval
One commenter suggested that the EPA should fully approve the HD I/
M Regulation as it applies to out-of-state vehicles but conditionally
approve the HD I/M Regulation as applied to in-state vehicles. The
commenter suggested that the conditional approval for in-state vehicles
should be conditional on the availability of alternative modes of
transportation for California laborers, citing the need to protect the
State's trucking industry from a decrease in trucking jobs that the
commenter anticipates will result from implementation of the HD I/M
Regulation. In support of approving the HD I/M Regulation for out-of-
state vehicles, the commenter argues that these vehicles produce the
most emissions in California and therefore must necessarily be
regulated.
The commenter argued that there would be no Commerce Clause
violation in approving the HD I/M Regulation for out-of-state vehicles
because the benefits associated with the HD I/M Regulation will
outweigh the associated burdens. The commenter also suggests that the
HD I/M Regulation should be adopted at the Federal level.
Response: We do not understand the CAA as authorizing the EPA to
take the action suggested by the commenter. As an initial matter, we
see no basis for us to condition approval of the HD I/M Regulation as
to in-state vehicles on the availability of replacement employment for
the California truckers the commenter believes may lose their jobs as a
result of the HD I/M Regulation. While we appreciate this concern, the
CAA does not require States to include measures that address such
adverse economic impacts that may result from emissions control
measures, and California has in its discretion decided to proceed with
the HD I/M Regulation despite the potential for losses to in-state
trucking jobs the commenter highlighted.
Conversely, however, we disagree that it would be appropriate to
fully approve, on a non-conditional basis, the HD I/M Regulation to the
extent it applies to out-of-state vehicles. Such an approval structure
would raise additional Commerce Clause concerns (if coupled with the
conditional approval discussed above) by providing protections for
California truckers that are not extended to out-of-state truckers. As
discussed above, the burdens imposed on out-of-state and out-of-country
owners and operators, and interstate commerce generally, in exchange
for localized benefits are relevant to the Commerce Clause analysis and
to the propriety of California's SIP submission under the CAA.
Comment 21: Full Disapproval
A member of the California State Assembly suggested that the EPA
should fully disapprove the submitted HD I/M Regulation. The commenter
pointed to concerns identified in the proposed rulemaking related to
CAA section 110(a)(2)(E)(i) and to the HD I/M Regulation's
enforceability and constitutionality, and argued that disapproving it
only for non-California vehicles would leave a materially different and
unvetted program. The commenter also argued that the costs and vehicle
downtime associated with the HD I/M Regulation confirms the need for a
uniform Federal approach rather than a California-specific rule.
Response: We disagree that the substantial concerns identified for
vehicles registered out-of-state would warrant disapproval of the HD I/
M Regulation for the reasons suggested. Additional comments relating to
[[Page 5348]]
compliance costs are addressed in our response to Comments 1 and 2.
Comment 22: Partial Disapproval Only for Vehicles Merely Passing
Through California
SCAQMD, while generally arguing in favor of full approval of the HD
I/M Regulation, suggested that any disapproval should be limited to
vehicles that merely pass through California, rather than vehicles that
conduct business in California and make one or more stops within the
State, arguing that this would address the EPA's most substantial
concerns.
Response: We do not consider the commenter's suggestion to be a
viable alternative to the EPA's proposed alternative actions for the
reason that it would not be practically enforceable as described.
Determining the applicability of the HD I/M Regulation to a particular
vehicle on the basis of whether the vehicle merely passes through
California or conducts business within the State would be difficult if
not impossible in practice. The comment, rather, highlights the
impermissible burdens the proposed SIP would place on out-of-state
residents and commercial enterprises. These costs would make it
prohibitively expensive for certain trucking companies to operate in
California or even to pass through California routed to other
destinations, thereby creating an economic burden felt throughout the
United States. ``This is particularly burdensome for trucks registered
out-of-state, which are considered non-compliant unless they test prior
to entering the state. These vehicles might operate in California for
only a few hours or days, rather than for weeks or months, but must
undergo testing to legally enter the state.'' \120\
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\120\ Comment ID EPA-R09-OAR-2025-0061-0047.
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Small proprietors also argued they would be forced to treat the HD
I/M Regulation as a national standard that mandates fleet replacement,
creates out-of-state permitting hurdles, risks fines levied against
non-California based businesses, and threatens downstream burdens to
other industries in need of transportation services.\121\
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\121\ See generally Comment ID EPA-R09-OAR-2025-0061-0015;
Comment ID EPA-R09-OAR-2025-0061-0016; Comment ID EPA-R09-OAR-2025-
0061-0018.
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IV. Incorporation by Reference
In this rule, the EPA is finalizing regulatory text that includes
incorporation by reference. In accordance with requirements of 1 CFR
51.5, the EPA is finalizing the incorporation by reference of CARB's
Heavy-Duty Vehicle Inspection and Maintenance Program, listed in table
1 of section I of this preamble: 13 CCR 2193 (amended); and new
sections 13 CCR 2195, 2195.1, 2196, 2196.1, 2196.2, 2196.3, 2196.4,
2196.5, 2196.6, 2196.7, 2196.8, 2197, 2197.1, 2197.2, 2197.3, 2198,
2198.1, 2198.2, 2199, and 2199.1, and the OBD Standards incorporated by
reference within the regulations. (As described in this action, our
approval is limited to vehicles registered in the State of California.)
These regulations control emissions from non-gasoline powered vehicles
travelling in California and weighing over 14,000 pounds. The EPA has
made, and will continue to make, these documents available through
<a href="https://www.regulations.gov">https://www.regulations.gov</a> and at the EPA Region IX Office (please
contact the person identified in the FOR FURTHER INFORMATION CONTACT
section of this preamble for more information). These materials have
been approved by the EPA for inclusion in the SIP, have been
incorporated by reference by the EPA into that plan, are federally
enforceable under sections 110 and 113 of the CAA as of the effective
date of the final rule of the EPA's partial approval, and will be
incorporated by reference in the next update to the SIP
compilation.\122\
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\122\ 62 FR 27968 (May 22, 1997).
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V. Statutory and Executive Order Reviews
Under the CAA, the Administrator is required to approve a SIP
submission that complies with the provisions of the Act and applicable
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in
reviewing SIP submissions, the EPA's role is to review State choices
and approve those choices if they meet the requirements of the Act.
Accordingly, this final action partially approves and partially
disapproves a State regulation as meeting Federal requirements and does
not impose additional requirements beyond those imposed by the State
regulation.
Additional information about these statutes and Executive Orders
can be found at <a href="https://www.epa.gov/laws-regulations/laws-and-executive-orders">https://www.epa.gov/laws-regulations/laws-and-executive-orders</a>.
A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review
This is a significant regulatory action as per Executive Order
12866 and was submitted to the Office of Management and Budget (OMB)
for review.
B. Executive Order 14192: Unleashing Prosperity Through Deregulation
This action is not an Executive Order 14192 regulatory action. The
SIP partial disapproval does not in-and-of itself create any new
requirements but simply disapproves certain State requirements for
inclusion in the SIP. The SIP approval does not impose any
requirements, but rather determines that th
[…truncated; see source link]Indexed from Federal Register on February 6, 2026.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.