In a unanimous decision, the US Supreme Court held Monday that passengers in a car stopped by police have the same right to challenge the constitutionality of that stop as the driver. The court held that when police stop a vehicle, the passengers are "seized" and have the right to challenge the legality of that seizure in court.

The ruling came in the case of California resident Bruce Edward Brendlin, who was arrested on parole violation and drug charges after the car in which he was riding was pulled over for what turned out to be bogus reasons by police. Once police had stopped the vehicle, they ordered Brendlin out of the car, searched him, the driver, and the vehicle, and found a syringe cap, a small amount of marijuana, and ingredients used to home cook methamphetamine.

While the driver of the vehicle did not challenge the constitutionality of the traffic stop, Brendlin did. He filed a motion to suppress the evidence against him, arguing that the traffic stop amounted to "an unlawful seizure of his person."

A California appeals court agreed, but the California Supreme Court overturned the appeals court decision. Instead, the California high court agreed with the state that even though police "had no adequate justification" to stop the vehicle in which Brendlin was riding, only the driver -- not any passengers -- had been "seized." Passengers in a vehicle stopped by police "would feel free to depart or otherwise to conduct his or her affairs as though the police were not present," the court reasoned.

But the US Supreme Court begged to differ. Any "reasonable passenger" would not feel free to simply leave the scene of a traffic stop, wrote Justice David Souter in the opinion in Brendlin v. California. "A traffic stop necessarily curtails the travel a passenger has chosen just as much as it halts the driver," Souder wrote. "Brendlin was seized from the moment [the driver's] car came to a halt on the side of the road, and it was error to deny his suppression motion on the ground that seizure occurred only at the formal arrest."

To find in favor of California's position that passengers are not "seized" during a traffic stop "would invite police officers to stop cars with passengers regardless of probable cause or reasonable suspicion of anything illegal," Souter wrote. "The fact that evidence uncovered as a result of an arbitrary traffic stop would still be admissible against any passengers would be a powerful incentive to run the kind of 'roving patrols' that would still violate the driver's Fourth Amendment right."