## Facts

- Federal officers patrolling near the Oklahoma–Missouri border recognized Brinegar and his car traveling west into Oklahoma close to the state line.
- A federal agent previously had arrested Brinegar for illegal liquor transportation and had twice personally observed him loading liquor in Missouri.
- The agent also knew Brinegar had a reputation for hauling liquor.
- The officers observed Brinegar’s car appearing heavily loaded and stopped it on the highway.
- After questioning, Brinegar admitted he had twelve cases of liquor in the vehicle; the officers then searched the car, seized the liquor, and arrested him.
- Brinegar moved to suppress the liquor as the product of an unreasonable warrantless search; the motion was denied, and he was convicted under the Liquor Enforcement Act of 1936 for transporting liquor into Oklahoma contrary to state law.

## Issues

1. Whether the warrantless stop, search of Brinegar’s automobile, and seizure of liquor were supported by probable cause under the Fourth Amendment.
2. Whether the officers could rely on prior knowledge of Brinegar’s conduct and reputation, along with contemporaneous observations, to establish probable cause rather than mere suspicion.
3. Whether evidence of Brinegar’s prior arrest could be considered at a suppression hearing to assess probable cause even if excluded at trial on guilt.

## Decision

- The Supreme Court affirmed the conviction.
- The Court held the officers had probable cause based on facts known before Brinegar’s admission; the warrantless automobile search and seizure were reasonable.
- The Court followed the automobile-search rule of *Carroll v. United States*, permitting warrantless vehicle searches on public highways when probable cause exists and obtaining a warrant is impracticable.
- The Court approved considering Brinegar’s prior arrest and the agent’s personal observations at the suppression hearing to assess probable cause, notwithstanding different trial admissibility rules.

## Legal Principles

- Probable cause exists when facts and circumstances within the officers’ knowledge, and reasonably trustworthy information, would warrant a person of reasonable caution in believing an offense is being committed.
- Probable cause is a practical, nontechnical standard based on everyday judgments; it demands less than proof beyond a reasonable doubt.
- Warrantless searches of automobiles on public highways may be reasonable when officers have probable cause and the vehicle’s mobility makes a warrant difficult to obtain.
- Fourth Amendment reasonableness allows some reasonable mistakes by officers confronted with ambiguous circumstances, but does not permit searches based on whim, caprice, or suspicion alone.
- Information relevant to probable cause may include prior police knowledge and conduct history, and may be considered at suppression proceedings even if excluded at trial on guilt.

## Conclusion

The Court upheld a warrantless automobile search where officers had probable cause grounded in specific prior knowledge and contemporaneous observations, and it articulated a practical definition of probable cause that governs Fourth Amendment assessments of reasonableness in vehicle searches.


Brinegar v. United States, 338 U.S. 160 (1949)