WASHINGTON - The Supreme Court ruled today that police need a warrant to search the vehicle of someone they have arrested if the person is locked up in a patrol cruiser and poses no safety threat to officers.

The court's 5-4 decision in a case from Arizona puts new limits on the ability of police to search a vehicle immediately after the arrest of a suspect, particularly when the alleged offense is nothing more serious than a traffic violation.

Justice John Paul Stevens said in the majority opinion that warrantless searches still may be conducted if a car's passenger compartment is within reach of a suspect who has been removed from the vehicle or there is reason to believe evidence will be found of the crime that led to the arrest.