Knowles v. Iowa, 525 U.S. 113; 119 S. Ct. 484; 142 L. Ed. 2d 492 (1998)
Facts—An officer stopped Knowles for speeding. He issued Knowles a citation but did not arrest him. He did, however, perform a full search of the car, for which he had neither Knowles’s consent nor probable cause, and discovered marijuana and a “pot pipe” in the process. The trial court and the Iowa Supreme Court rejected Knowles’s request to suppress this evidence, and he was convicted.
Question—Does a speeding citation, issued without an arrest, justify a search of an entire vehicle?
Decision—No, the arrest was unjustified and the products thereof must be excluded.
Reasons—C.J. Rehnquist (9–0). In United States v. Robinson, 414 U.S. 218 (1973), the Supreme Court permitted the search of a vehicle incident to an arrest. That decision was based on the possible need to disarm a suspect being taken into custody and the need to preserve evidence for later use at a trial. Neither rationale was present here. The officer could have provided for his safety without a full search of the car. Moreover, a search of the car would not lead to any further evidence needed to prosecute the speeding violation.