Three police officers, including Maria Trevizo, pulled over a car with a suspended registration. One of the occupants, Lemon Johnson, wore clothing consistent with membership in a gang. Trevizo searched him for officer safety and found a gun. Johnson was charged with illegal possession of a weapon. [Arizona v. Johnson, 555 U.S. 323, 129 S.Ct. 781, 172 L.Ed.2d 694 (2009)].

Questions: What standard should apply to an officers search of a passenger during a traffic stop? Should a warrant be required? Could a search proceed solely on the basis of probable cause? Would a reasonable suspicion short of probable cause be enough?