Illinois v. Caballes

The initial seizure of the defendant was lawful as the officer established probable cause the defendant was speeding. However, a seizure that is justified at its inception by the officer’s desire to write a ticket can become unlawful if the stop is prolonged beyond the time reasonably required to write the ticket. In this case, the court concluded the duration of the stop was entirely justified by the traffic offense and the ordinary tasks an officer must complete incident to such a stop.

In addition, the court found that conducting a dog sniff, by itself, does not change the character of a lawful seizure, as long as the dog sniff does not infringe upon the defendant’s privacy interests. Consequently, the court held the use of a “well-trained narcotics-detection dog” during a lawful traffic stop, generally does not implicate legitimate privacy interests. Here, the dog sniff was performed on the exterior of the defendant’s car while he was lawfully seized for a traffic violation. Such a dog sniff that reveals no information other than the location of a substance that no individual has any right to possess does not violate the Fourth Amendment.