Why Vehicles Are Different

Why Vehicles Are Different

The early statutes relied on in Carroll show that the law long separated goods hidden in a dwelling from goods carried in something movable, but they do not say why movability should weaken the warrant requirement. The Supreme Court has since given two reasons, and they arrived at different times. Carroll supplied the first: a vehicle can be quickly moved out of the locality or jurisdiction in which a warrant must be sought, which is why the Court saw a “necessary difference” between searching “a store, dwelling house or other structure” and searching “a ship, motor boat, wagon or automobile.”¹ Ready mobility was the core justification for many years, and later cases added a second one resting on the pervasive regulation of vehicles that travel public highways.²

The two reasons answer different halves of one balancing question. A warrant requirement asks the government to accept a cost, the delay of going to a magistrate, in order to protect an interest, the occupant's privacy. Mobility raises the cost, because with a car the delay can mean the evidence is gone before the warrant arrives. Reduced privacy lowers the value of what the delay would buy. A person who drives a licensed vehicle on public roads already lives with periodic inspections, licensing requirements, and routine police stops for expired tags or faulty equipment, so a roadside search reaches into a less protected space than a search of a home would.³ When both pressures are present, the schemes of regulation and the exigencies of ready mobility together justify a search without prior recourse to a magistrate, so long as the overriding standard of probable cause is met.⁴

The two reasons do not carry equal weight today. The Court has acknowledged that warrantless vehicle searches have been permitted “in cases in which the possibilities of the vehicle's being removed or evidence in it destroyed were remote, if not non-existent,” which shows that the privacy rationale can carry the exception when mobility is weak.⁵ Cardwell v. Lewis, which allowed a warrantless seizure and search of a car in a public parking lot after the driver's arrest elsewhere, is an example of the privacy rationale doing that work.⁶ The same logic explains why a car already towed to a police station can still be searched without a warrant, a result reached in Chambers v. Maroney and taken up in its own section below.⁷

Both justifications describe a thing in its character as a vehicle, so neither can be borrowed by a house. The Court said as much when it announced each of them, taking care to limit the rationales to automobiles and to describe them as supporting “treating automobiles differently from houses.”⁸ In California v. Carney both justifications operated at once. Agents had watched a motor home in a San Diego lot, and the Court upheld the warrantless search because the vehicle was readily mobile, was licensed to operate on public streets and subject to extensive regulation and inspection, and was situated so that an objective observer would conclude it was being used as a vehicle and not as a residence.⁹

Collins v. Virginia shows the other side of the line. A motorcycle is a vehicle, yet where one sat under a tarp in a driveway a few feet from a house, the Court held that the officer's warrantless search violated the Fourth Amendment, after concluding that the driveway was curtilage, the area immediately surrounding and associated with the home and treated as part of the home itself.¹⁰ What separates Collins from Carney is where the vehicle stood, and the location matters because ready mobility and pervasive regulation describe vehicles on the road, and they say nothing about the home beside which one happens to be parked. An exam stem that places a mobile vehicle at a residence invites the mistake of applying the exception because the object is a car, when the answer turns on where the vehicle sits. The curtilage limit has its own section at the end of this chapter. The next two subsections take the justifications one at a time, beginning with ready mobility.

Ready Mobility

The first justification for the automobile exception is the simplest to state, because a vehicle can leave. Carroll reasoned that an automobile's mobility makes it impracticable to obtain a warrant before the vehicle may be driven away, since the car can be moved quickly out of the locality or jurisdiction in which the warrant must be sought.¹² The warrant process takes time and pulls the officer away from the scene. A store or dwelling house waits out that delay, but a car does not, so an officer with probable cause at the roadside may return with a warrant and find nothing left to search. This ready-mobility rationale is the reason the exception treats a vehicle differently from the buildings along the road.

Chambers v. Maroney explains why that delay is so costly. The facts that give probable cause to search a particular car usually surface without warning, and the chance to act on them is fleeting because the car is readily movable.¹³ In Chambers itself, police stopped a light blue station wagon carrying four men within an hour of a service-station robbery. One man wore a green sweater and a trench coat lay in the car, matching the descriptions broadcast after the robbery.¹⁴ The officers could not have planned a warrant application around that car, because they had no way of knowing where it would turn up. Once it was stopped, the occupants were alerted, and the contents might never be found again if the car were released while a warrant was pursued.¹⁵ The officers' real choice was therefore between searching at once without a warrant and seizing the car and holding it, also without a warrant, for as long as obtaining one took. The Court saw no constitutional difference between the two, because with probable cause present either course is reasonable.¹⁶

The Court did not treat holding the car as the gentler option, and the reason is functional. Which intrusion counts as the greater one is debatable and depends on the circumstances.¹⁷ Holding a car while officers seek a warrant burdens the owner's property and delays occupants who may be forced to wait, whereas an immediate search rests on probable cause that can still be tested later before a neutral magistrate at a suppression hearing.¹⁸ Since neither course is clearly less intrusive, the rule leaves the choice with the officer and requires only probable cause.

Chambers shows the rationale at full strength: a car on a public road, occupants who know the police have found them, and a search that happens now or may never happen. Carroll marks the opposite pole by contrasting a house, which is a permanent structure, with an automobile, which is a movable object.¹⁹ Where nothing can drive away, the reason for skipping the warrant disappears, so probable cause about a fixed structure leaves officers to seek a warrant.

Because the justification attaches to the nature of the vehicle, officers need not show in the individual case that the car was about to leave or that a warrant was hard to get. The exception has no separate exigency requirement, which means no showing of circumstances that prevented or complicated obtaining a warrant is demanded.²⁰ A parked car qualifies as well, since a vehicle is readily mobile by the turn of an ignition key even when it is not moving.²¹ The exception applies whether or not the car is being driven at the time of the stop, so long as it is capable of moving.²² Students lose points here by writing that officers had to prove the car was about to be driven away, when the capacity to move is enough.

The mobility rationale has its critics. The dissent in United States v. Ross called it "something of a misnomer," because police ordinarily can remove the occupants and secure the vehicle on the spot.²³ The same dissent conceded that mobility often leaves police with no alternative to an immediate search except releasing the car and risking the loss of its contents.²⁴ Its objection bites where officers have cause to arrest the occupants and can bring the car to the station, since a vehicle in the exclusive control of the authorities can no longer be driven away. For that situation the dissent explained a prompt search by a second major justification, the diminished expectation of privacy in an automobile.²⁵ That is the dissent's critique, and the majority's statement of the doctrine kept mobility and reduced privacy expectations together as the grounds for the exception.²⁶ A rationale tied to the moment of the roadside stop explains less once the car is in police hands, which is why the second justification matters and why the next subsection takes it up.

Reduced Privacy Expectations

The second justification rests on how closely the government already supervises vehicles that use public roads. In South Dakota v. Opperman the Court observed that automobiles, unlike homes, are subjected to “pervasive and continuing governmental regulation and controls, including periodic inspection and licensing requirements.”²⁸ Police stop and examine vehicles as an everyday occurrence when license plates or inspection stickers have expired, or when headlights or other safety equipment are not working.²⁹ A person's expectation of privacy follows from what that person has reason to expect, and a driver has repeated experience of officials examining the vehicle itself through licensing, inspection, and roadside stops. Drivers are therefore on notice that a vehicle may be stopped and searched on facts giving rise to probable cause without a magistrate's prior review.³⁰ This reduced expectation of privacy lowers the value of what a warrant would protect, so the rationale can support a warrantless search even when waiting for a warrant would cost the officers nothing.

The Court has located the source of that diminished expectation in regulation. An earlier explanation pointed to a car's windows, through which passers-by can look in, but a visibility theory cannot account for how far the exception reaches.³¹ The exception has been applied to a locked car trunk and to a sealed package inside one, places no passer-by can see into.³² Regulation explains those results, because a trunk is as much a part of a licensed, inspected vehicle as the dashboard is. An explanation that treats a car as less private because anyone can look inside it misidentifies the source, which is pervasive regulation.

The privacy rationale also covers ground the mobility rationale cannot. Mobility describes a car at the moment of the roadside stop, while the diminished expectation describes the car as a kind of object, and a car does not stop being a licensed, inspected road vehicle because the police have towed it. The same Ross dissent that questioned the mobility rationale accepted this division of labor: when officers can arrest the occupants and bring the car to the station, mobility no longer justifies a search, and the diminished expectation of privacy in an automobile does.³³ That is the setting of Chambers v. Maroney, where the car was searched at the station and the Court still upheld the search.³⁴ Later decisions, including Pennsylvania v. Labron and Maryland v. Dyson, kept resting the exception on the diminished expectation of privacy in cars.³⁵

The reduced expectation is a lowered one, and probable cause still has to be present before the search begins.³⁶ The rationale also attaches to the vehicle, and United States v. Chadwick shows where that stops. Police there searched a double-locked footlocker that had just been placed in an open car trunk, and the Court declined to treat it like a vehicle search. The footlocker was not open to public view, was not subject to regular inspection and official scrutiny, and was intended as a repository of personal effects.³⁷ Containers found inside a car under probable cause to search the car raise a separate question, which the scope subsections below take up.

Because the diminished expectation comes from the regulation of vehicles, it carries no weight where the thing searched is a home. The Court took care to say that both justifications apply only to automobiles and not to houses, and so support treating automobiles differently from houses as a constitutional matter.³⁸ A car driven on public roads under registration, inspection, and stop-and-check rules shows the rationale at full strength, and officers with probable cause may search it. The home is at the opposite pole. It is first among equals under the Fourth Amendment, and its curtilage, the area immediately surrounding and associated with the home, counts as part of the home itself.³⁹ In Collins v. Virginia the object was a motorcycle, a vehicle as regulated as any other, yet it sat under a tarp in a driveway a few feet from a house, and the Court held that the officer's warrantless search violated the Fourth Amendment.⁴⁰ The regulation of motorcycles describes motorcycles and gives no reason to lower the protection of the home beside which one is parked.