The law of autombile stops and searches is bounded by the warrant requirement, the plain view doctrine, and the fourth amendment. If police officers have probable cause to believe that an automobile contains contraband or the fruits of crime, they may stop a vehicle and search it. Their probable cause must be grounded in objective facts that would justify the issuance of a search warrant. When police officers make a lawful custodial arrest of a car's driver or passenger, they may also, as a part of the arrest, search the automobile. Other situations justifying stops and searches are discussed: administrative traffic checkpoints, inventory searches, investigations based on an articulable suspicion, and voluntary consent. When enforcement officers often have difficulty in identifying adjudicating automobile search issues, Illinois courts usually follow the U.S. Supreme Court's interpretation of the fourth amendment. Law enforcement officers often have difficulty in identifying the legal justification for a vehicle search, and most situations admit to exceptions to the search warrant requirement. 264 footnotes.