A federal agent patrolling a highway suspected that a truck and a car driving together were trafficking drugs. The agent radioed a highway patrolman and attempted to pull over both vehicles. The agent was able to get the car to pull over, but the truck, driven by Savage (defendant), did not pull over immediately. The patrolman followed the truck and eventually got it to pull over. The agent, still at the car he originally pulled over, called for more assistance. When local police showed up at the car, the agent left the police to watch the car and the suspect. The agent then drove to where the patrolman had pulled over the truck. The agent smelled marijuana, searched the truck, and found marijuana in the truck. Savage was detained for approximately 20 minutes from when he was pulled over to when the drugs were found. The court of appeals held that the extended detention without probable cause violated the defendants’ Fourth Amendment rights. The United States Supreme Court granted certiorari.