Facts
- During Prohibition, federal agents suspected George Carroll of illicit liquor trafficking and had earlier attempted an undercover liquor purchase from him that was arranged but not completed.
- While patrolling the highway between Detroit and Grand Rapids, Michigan—a route associated with liquor smuggling—agents recognized Carroll and John Kiro driving an Oldsmobile roadster.
- Agents stopped the vehicle and searched it without a warrant.
- The search revealed bottles of intoxicating liquor concealed behind the rear-seat upholstery.
- The government relied on § 26 of Title II of the National Prohibition Act, which directed seizure when an officer discovers a person “in the act of transporting” illegal liquor in an automobile.
- Carroll and Kiro were convicted of transporting intoxicating liquor; they argued the liquor evidence was obtained through an unreasonable search and seizure under the Fourth Amendment.
Issues
- Whether a warrantless search of an automobile on a public highway violates the Fourth Amendment when officers have probable cause to believe the vehicle contains contraband liquor.
- Whether automobile mobility and impracticability of obtaining a warrant can justify a warrantless search, and what limits apply.
Decision
- The Court affirmed admission of the liquor evidence and upheld the convictions.
- A warrantless search of an automobile for contraband is not unreasonable under the Fourth Amendment if based on probable cause.
- The Court distinguished searches of fixed structures (where warrants are typically practicable) from searches of vehicles that can be quickly moved out of the jurisdiction.
- The Court rejected suspicionless vehicle stops and searches, stressing that officers may not search cars “at will” or on mere chance.
- The Court stated that when obtaining a warrant is reasonably practicable, a warrant must be used.
- A dissent argued the rule risked expanding officer discretion and weakening Fourth Amendment protections.
Legal Principles
- The Fourth Amendment prohibits unreasonable searches and seizures; warrantless searches may be lawful if reasonable under the circumstances.
- Officers may search an automobile without a warrant when they have probable cause—i.e., a reasonable belief based on known circumstances—that it contains contraband subject to seizure.
- Automobile mobility can make obtaining a warrant impracticable, supporting warrantless action when probable cause exists.
- Random or suspicionless stopping and searching of vehicles is impermissible; lawful highway travel is protected absent probable cause.
- The warrant requirement remains preferred; warrantless vehicle searches are limited to situations where use of a warrant is not reasonably practicable.
Conclusion
The Court recognized an automobile-specific exception to the warrant requirement, holding that a warrantless highway search is consistent with the Fourth Amendment when officers have probable cause to believe the vehicle contains contraband and obtaining a warrant is not reasonably practicable.