Amendment 4 — Vehicle Searches

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Fourth Amendment :

The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.

In the early days of the automobile, the Court created an exception for searches of vehicles, holding in Carroll v. United States[1](https://www.law.cornell.edu/constitution-conan/amendment-4/vehicle-searches#fn1amd4 " 267 U.S. 132 (1925). Carroll was a Prohibition-era liquor case, whereas a great number of modern automobile cases involve drugs. ") that vehicles may be searched without warrants if the officer undertaking the search has probable cause to believe that the vehicle contains contraband. The Court explained that the mobility of vehicles would allow them to be quickly moved from the jurisdiction if time were taken to obtain a warrant.[2](https://www.law.cornell.edu/constitution-conan/amendment-4/vehicle-searches#fn2amd4 " Id. at 153. See also Husty v. United States, 282 U.S. 694 (1931); Scher v. United States, 305 U.S. 251 (1938); Brinegar v. United States, 338 U.S. 160 (1949). All of these cases involved contraband, but in Chambers v. Maroney, 399 U.S. 42 (1970), the Court, without discussion, and over Justice John Harlan’s dissent, id. at 55, 62, extended the rule to evidentiary searches. ")

Initially, the Court limited Carroll's reach, holding impermissible the warrantless seizure of a parked automobile merely because it is movable, and indicating that vehicles may be stopped only while moving or reasonably contemporaneously with movement.[3](https://www.law.cornell.edu/constitution-conan/amendment-4/vehicle-searches#fn3amd4 " Coolidge v. New Hampshire, 403 U.S. 443, 458–64 (1971). This portion of the opinion had the adherence of a plurality only, Justice John Harlan concurring on other grounds, and there being four dissenters. Id. at 493, 504, 510, 523. ") The Court also ruled that the search must be reasonably contemporaneous with the stop, so that it was not permissible to remove the vehicle to the station house for a warrantless search at the convenience of the police.[4](https://www.law.cornell.edu/constitution-conan/amendment-4/vehicle-searches#fn4amd4 " Preston v. United States, 376 U.S. 364 (1964); Dyke v. Taylor Implement Mfg. Co., 391 U.S. 216 (1968). ")

The Court next developed a reduced privacy rationale to supplement the mobility rationale, explaining that “the configuration, use, and regulation of automobiles often may dilute the reasonable expectation of privacy that exists with respect to differently situated property.” [5](https://www.law.cornell.edu/constitution-conan/amendment-4/vehicle-searches#fn5amd4 " Arkansas v. Sanders, 442 U.S. 753, 761 (1979). ") “One has a lesser expectation of privacy in a motor vehicle because its function is transportation and it seldom serves as one’s residence or as the repository of personal effects. . . . It travels public thoroughfares where both its occupants and its contents are in plain view.’” [6](https://www.law.cornell.edu/constitution-conan/amendment-4/vehicle-searches#fn6amd4 " Cardwell v. Lewis, 417 U.S. 583, 590 (1974) (plurality opinion), quoted in United States v. Chadwick, 433 U.S. 1, 12 (1977). See also United States v. Ortiz, 422 U.S. 891, 896 (1975); United States v. Martinez-Fuerte, 428 U.S. 543, 561 (1976); South Dakota v. Opperman, 428 U.S. 364, 367–68 (1976); Robbins v. California, 453 U.S. 420, 424–25 (1981); United States v. Ross, 456 U.S. 798, 807 n.9 (1982). ") Although motor homes serve as residences and as repositories for personal effects, and their contents are often shielded from public view, the Court extended the automobile exception to them as well, holding that there is a diminished expectation of privacy in a mobile home parked in a parking lot and licensed for vehicular travel, hence “readily mobile.” [7](https://www.law.cornell.edu/constitution-conan/amendment-4/vehicle-searches#fn7amd4 " California v. Carney, 471 U.S. 386, 393 (1985) (leaving open the question of whether the automobile exception also applies to a “mobile” home being used as a residence and not “readily mobile” ). ")

The Court has stated, however, that the automobile exception “does not permit an officer without a warrant to enter a home or its curtilage in order to search a vehicle therein.” [8](https://www.law.cornell.edu/constitution-conan/amendment-4/vehicle-searches#fn8amd4 " Collins v. Virginia, 138 S. Ct. 1663, 1675 (2018); see also Caniglia v. Strom, No. 20-157, slip op. at 3–4 (U.S. May 17, 2021) (rejecting an expanded “community caretaking” rule and holding that there is an “unmistakable distinction between vehicles and homes,” and declining to “expand the scope of exceptions to the warrant requirement to permit warrantless entry into the home” ). ") This limit to the exception exists because “the scope of the automobile exception extends no further than the automobile itself.” [9](https://www.law.cornell.edu/constitution-conan/amendment-4/vehicle-searches#fn9amd4 " Id. at 1671. ") To search a vehicle under the automobile exception, an officer “must have a lawful right of access” to that vehicle,[10](https://www.law.cornell.edu/constitution-conan/amendment-4/vehicle-searches#fn10amd4 " Id. at 1672. ") and generally, law enforcement officers have no right to enter a home or its curtilage without express or implied permission or without a warrant.[11](https://www.law.cornell.edu/constitution-conan/amendment-4/vehicle-searches#fn11amd4 " See, e.g., Florida v. Jardines, 569 U.S. 1, 7–8 (2013). ")

The reduced expectancy concept has broadened police powers to conduct automobile searches without warrants, but they still must have probable cause to search a vehicle,[12](https://www.law.cornell.edu/constitution-conan/amendment-4/vehicle-searches#fn12amd4 " Almeida-Sanchez v. United States, 413 U.S. 266 (1973) (roving patrols); United States v. Ortiz, 422 U.S. 891 (1975). Cf. Colorado v. Bannister, 449 U.S. 1 (1980). An automobile’s “ready mobility [is] an exigency sufficient to excuse failure to obtain a search warrant once probable cause is clear” ; there is no need to find the presence of “unforeseen circumstances” or other additional exigency. Pennsylvania v. Labron, 527 U.S. 465 (1996). Accord, Maryland v. Dyson, 527 U.S. 465 (1999) (per curiam). Cf. Florida v. Harris, 568 U.S. 237 (2013). ") and they may not make random stops of vehicles on the roads but instead must base stops of individual vehicles on probable cause or some “articulable and reasonable suspicion” [13](https://www.law.cornell.edu/constitution-conan/amendment-4/vehicle-searches#fn13amd4 " Delaware v. Prouse, 440 U.S. 648, 663 (1979) (discretionary random stops of motorists to check driver’s license and automobile registration constitute Fourth Amendment violation); United States v. Brignoni-Ponce, 422 U.S. 873 (1975) (affirming an appellate court’s judgment that stopping a vehicle on a highway near an international border merely because the occupants appeared to be of Mexican ancestry was an unconstitutional search for unlawfully present aliens). But cf. United States v. Arvizu, 534 U.S. 266 (2002) (reasonable suspicion justified stop by border agents of vehicle traveling on unpaved backroads in an apparent effort to evade a border patrol checkpoint on the highway). In Prouse, the Court cautioned that it was not precluding the states from developing methods for spot checks, such as questioning all traffic at roadblocks, that involve less intrusion or that do not involve unconstrained exercise of discretion. 440 U.S. at 663. ") of traffic or safety violation or some other criminal activity.[14](https://www.law.cornell.edu/constitution-conan/amendment-4/vehicle-searches#fn14amd4 " For example, an officer who learns, through a license plate search of a vehicle, that the registered owner has a revoked license may have a reasonable suspicion to stop that vehicle if it matches the description of the registered car and if, at the time of the stop, the officer has no countervailing reason to think the driver is not the registered owner. Kansas v. Glover, 140 S. Ct. 1183, 1184, 1191 (2020). An officer who observes a traffic violation may stop a vehicle even if his real motivation is to investigate for evidence of other crime. Whren v. United States, 517 U.S. 806 (1996). The existence of probable cause to believe that a traffic violation has occurred establishes the constitutional reasonableness of traffic stops regardless of the actual motivation of the officers involved, and regardless of whether it is customary police practice to stop motorists for the violation observed. Similarly, pretextual arrest of a motorist who has committed a traffic offense is permissible. Arkansas v. Sullivan, 532 U.S. 769 (2001) (per curiam) (upholding search of the motorist’s car for a crime not related to the traffic offense). ") If police stop a vehicle, then the vehicle’s passengers as well as its driver are deemed to have been seized from the moment the car comes to a halt, and the passengers as well as the driver may challenge the constitutionality of the stop.[15](https://www.law.cornell.edu/constitution-conan/amendment-4/vehicle-searches#fn15amd4 " Brendlin v. California, 551 U.S. 249, 263 (2007). ") A driver with lawful possession and control of a rental car may also be able to challenge the constitutionality of a stop, even if that driver is not listed as an authorized driver on the rental agreement.[16](https://www.law.cornell.edu/constitution-conan/amendment-4/vehicle-searches#fn16amd4 " Byrd v. United States, 138 S. Ct. 1518, 1523–24 (2018). But see id. at 1529 (noting that a “car thief would not have a reasonable expectation of privacy in a stolen car” ). ") Likewise, a police officer may frisk (pat down for weapons) both the driver and any passengers whom he reasonably concludes “might be armed and presently dangerous.” [17](https://www.law.cornell.edu/constitution-conan/amendment-4/vehicle-searches#fn17amd4 " Arizona v. Johnson, 129 S. Ct. 781, 786 (2009). ")

By contrast, fixed-checkpoint stops in the absence of any individualized suspicion have been upheld for purposes of promoting highway safety[18](h