## Facts

- U.S. Border Patrol operated a fixed checkpoint on Interstate 5 south of San Clemente, California, but it was closed due to bad weather.
- Agents conducted a roving patrol north of the checkpoint and observed a vehicle driven by Felix Humberto Brignoni-Ponce with two passengers.
- Agents pursued and stopped the vehicle; they testified their only reason for the stop was the occupants’ apparent Mexican ancestry.
- After the stop, agents questioned the occupants about citizenship and learned the passengers had entered the United States illegally.
- Agents arrested all three occupants, and Brignoni-Ponce was charged with two counts of knowingly transporting illegal aliens under the Immigration and Nationality Act § 274(a)(2).
- The district court denied a motion to suppress testimony obtained as a result of the stop, and Brignoni-Ponce was convicted.
- The Ninth Circuit reversed on Fourth Amendment grounds, and the Supreme Court granted certiorari.

## Issues

1. Whether Border Patrol officers on roving patrol may stop a vehicle near the Mexican border to question occupants about citizenship when the only basis is apparent Mexican ancestry.
2. What level of suspicion the Fourth Amendment requires for roving patrol vehicle stops away from the border or its functional equivalent.

## Decision

- The Supreme Court affirmed the Ninth Circuit’s judgment.
- A roving Border Patrol stop to question occupants about citizenship is unconstitutional when based solely on apparent Mexican ancestry.
- Away from the border and its functional equivalent, officers may stop vehicles only when they have reasonable suspicion based on specific, articulable facts and rational inferences that the vehicle contains aliens illegally in the country.
- Because the stop violated the Fourth Amendment, evidence derived from the stop was inadmissible and the conviction could not stand.

## Legal Principles

- The Fourth Amendment requires balancing the public interest against an individual’s right to be free from arbitrary law enforcement interference.
- Roving patrol officers may briefly stop a vehicle and ask about citizenship and immigration status only on reasonable suspicion supported by specific, articulable facts and rational inferences.
- Apparent ethnic ancestry may be considered as one factor, but it cannot be the sole basis for reasonable suspicion.
- Further detention or a search after a roving patrol stop requires consent or probable cause.
- Immigration enforcement authority does not reduce Fourth Amendment protections of citizens who may be mistakenly targeted.

## Conclusion

Roving Border Patrol stops for immigration questioning are permitted only on reasonable suspicion grounded in specific, articulable facts; stopping a vehicle solely because the occupants appear to be of Mexican ancestry violates the Fourth Amendment and requires suppression of resulting evidence.


United States v. Brignoni-Ponce, 422 U.S. 873 (1975)