The US Supreme Court ruled Monday that police officers have the right to frisk passengers in cars stopped for traffic offenses even if they have no evidence the passenger has committed a crime or is about to do so. The ruling marks the latest in a now long line of high court decisions since the end of the Warren court -- many of them in drug cases -- that have eroded the Fourth Amendment's proscription against warrantless searches.

[inline:car-search.jpg align=left]In its decision, the Supreme Court unanimously rejected an Arizona appeals court ruling that threw out the evidence in one such search as unconstitutionally obtained.

The ruling came in Arizona v. Johnson, in which Lemon Johnson was the back seat passenger in a car pulled over by anti-gang police in Oro Valley. After questioning Johnson in the car and being informed that he was from "a place [the officer] knew was home to a Crips gang" and that he had served time for burglary, the officer, the officer asked him to get out of the car for further questioning. Noting also that Johnson wore a blue bandana and had a scanner in his pocket, the officer "patted him down for officer safety."

During the pat-down search, the officer found a pistol and a small bag of marijuana. Johnson was charged with weapons and drug possession offenses. He was convicted at trial, but that conviction was overturned by the appeals court, which held that although Johnson had been lawfully detained when police stopped the car for the traffic violation, during the course of the encounter before Johnson was frisked, the detention had "evolved into a separate, consensual encounter stemming from an unrelated investigation by [the officer] of Johnson's possible gang affiliation." Without "reason to believe Johnson was involved in criminal activity," the court ruled, the officer "had no right to pat him down for weapons, even if she had reason to suspect he was armed and dangerous."

That's not right, the Supreme Court said in a ruling authored by Justice Ruth Bader Ginsburg. Citing case law going back to Terry v. Ohio (1968), which established that police may constitutionally stop and interrogate people if they reasonably believe a crime has been or is about to be committed and that police can then frisk them to search for weapons, Ginsburg and the court ruled that such pat-down searches are allowable if police "harbor reasonable suspicion that a person subjected to the frisk is armed, and therefore dangerous to the safety of the police and public."