An Iowa police officer stopped D for speeding. D having been clocked driving 43 miles per hour on a road where the speed limit was 25 miles per hour. The officer issued a citation although under Iowa law he might have arrested him. The officer then conducted a full search of the car. Under the driver's seat, he found a bag of marijuana and a “pot pipe.” D was arrested and charged with violation of state laws dealing with controlled substances. D moved to suppress the evidence. D argued that the search was not a “search incident to arrest” exception recognized in United States v. Robinson because he had never placed under arrest. The police officer conceded that he had neither consent nor probable cause to conduct the search. The officer relied on a statute that allows peace officers having cause to believe that a person has violated any traffic or motor vehicle equipment law may arrest the person and immediately take the person before a magistrate. The law also authorizes the issuing a citation in lieu of arrest or in lieu of continued custody after an initial arrest. Based on this authority, the trial court denied the motion to suppress and found D guilty. The Supreme Court of Iowa affirmed. The Supreme Court granted certiorari.