The 1925 Carroll case established that automobiles were an exception to the fourth amendment prohibition of warrantless searches because the vehicle could be quickly moved out of the jurisdiction in which the warrant might be sought. The automobile exception includes four separate exceptions to the fourth amendment clause. In general, a search warrant is not needed if exigent circumstances indicate that a crime has been or will soon be committed, if no expectation of privacy exists regarding the location or object of the search, if the search is incident to an arrest, and if the evidence is in plain view. Each of these theories is at issue in the case of U.S. v. Ross which is now before the Supreme Court. In that case, a police officer searching a car trunk discovered an unsealed brown paper sack about the size of a lunch bag. The officer opened it and found 30 envelopes containing a white powder later found to be heroin. In the Ross case, the Goverment is trying to persuade the court to adopt a simple approach to the automobile exception by allowing an officer with a valid reason to stop and search an automobile to have the same authority as a warrant would provide. Defense lawyers are less interested in simplifying the automobile exception. Until the law is changed, police should adhere to the guidelines established under past Supreme Court decisions. Among these are the Prouse rule, which forbids the stopping of vehicles at random but which permits roadblocks at which every auto is stopped and checked, and the rules covering the searches on impounded automobiles and automobiles which have been seized under other circumstances.