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 States1 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
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 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
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 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 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
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 This limit to the exception exists because the scope of the automobile exception extends no further than the automobile itself.
9 To search a vehicle under the automobile exception, an officer must have a lawful right of access
to that vehicle,10 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
The reduced expectancy concept has broadened police powers to conduct automobile searches without warrants, but they still must have probable cause to search a vehicle12 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 of traffic or safety violation or some other criminal activity.14 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 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 Likewise, a police officer may frisk (patdown for weapons) both the driver and any passengers whom he reasonably concludes might be armed and presently dangerous.
17
By contrast, fixed-checkpoint stops in the absence of any individualized suspicion have been upheld for purposes of promoting highway safety18 or policing the international border,19 but not for more generalized law enforcement purposes.20 Once police have validly stopped a vehicle, they may also, based on articulable facts warranting a reasonable belief that weapons may be present, conduct a Terry-type protective search of those portions of the passenger compartment in which a weapon could be placed or hidden.21 And, in the absence of such reasonable suspicion as to weapons, police may seize contraband and suspicious items in plain view
inside the passenger compartment.22
Although officers who have stopped a car to issue a routine traffic citation may conduct a Terry-type search, even including a pat-down of driver and passengers if there is reasonable suspicion that they are armed and dangerous, they may not conduct a full-blown search of the car23 unless they exercise their discretion to arrest the driver instead of issuing a citation.24 And once police have probable cause to believe there is contraband in a vehicle, they may remove the vehicle from the scene to the station house in order to conduct a search, without thereby being required to obtain a warrant.25 [T]he justification to conduct such a warrantless search does not vanish once the car has been immobilized; nor does it depend upon a reviewing court’s assessment of the likelihood in each particular case that the car would have been driven away, or that its contents would have been tampered with, during the period required for the police to obtain a warrant.
26 Because of the lessened expectation of privacy, inventory searches of impounded automobiles are justifiable in order to protect public safety and the owner’s property, and any evidence of criminal activity discovered in the course of the inventories is admissible in court.27 The Justices were evenly divided, however, on the propriety of warrantless seizure of an arrestee’s automobile from a public parking lot several hours after his arrest, its transportation to a police impoundment lot, and the taking of tire casts and exterior paint scrapings.28
Police in undertaking a warrantless search of an automobile may not extend the search to the persons of the passengers therein29 unless there is a reasonable suspicion that the passengers are armed and dangerous, in which case a Terry patdown is permissible,30 or unless there is individualized suspicion of criminal activity by the passengers.31 But because passengers in an automobile have no reasonable expectation of privacy in the interior area of the car, a warrantless search of the glove compartment and the spaces under the seats, which turned up evidence implicating the passengers, invaded no Fourth Amendment interest of the passengers.32 Luggage and other closed containers found in automobiles may also be subjected to warrantless searches based on probable cause, regardless of whether the luggage or containers belong to the driver or to a passenger, and regardless of whether it is the driver or a passenger who is under suspicion.33 The same rule now applies whether the police have probable cause to search only the containers34 or whether they have probable cause to search the automobile for something capable of being held in the container.35