Brignoni-Ponce (defendant) was the driver of a vehicle in the northbound lanes of Interstate Highway 5 in southern California near the Mexican border. He was stopped by Border Patrol officers who were conducting a roving patrol of the area. The officers questioned Brignoni-Ponce and his two passengers, all of whom admitted that they were noncitizens who had entered the country illegally. The officers later stated that their only reason for stopping the car was that the vehicle’s occupants appeared to be of Mexican descent. Brignoni-Ponce was charged with knowingly transporting illegal immigrants. At trial, he moved to suppress the testimony of his two passengers, arguing that their statements were the fruit of an illegal seizure. The trial court denied the motion, the testimony was admitted, and Brignoni-Ponce was convicted. The court of appeal held that the motion to suppress should have been granted because the officers were not justified in making the stop based solely on the fact that the vehicle’s occupants appeared to be Mexican. The United States Supreme Court granted certiorari.