The police watched as a man entered his home carrying a package they had probable cause to believe contained marijuana. Before a search warrant could be obtained, Acevedo (defendant) arrived at the house and left after about ten minutes carrying a bag that was the same size as the package. Acevedo put the bag in the trunk of his car and drove away. Fearful of losing the evidence, the police followed him, pulled him over, opened the trunk and looked inside the bag, finding marijuana. The California Court of Appeals held that the marijuana found in the bag should have been suppressed at trial because the police needed a warrant to search the bag. The court of appeals also found that the bag did not fall under the automobile exception since the police had probable cause that the bag, not the car, contained drugs. The United States Supreme Court granted certiorari.