Warrant Exception: Traffic Checkpoints

In this chapter, we consider two situations in which the Court has authorized warrantless searches: (1) checkpoints, generally aimed at protecting the public from intoxicated drivers, and (2) “protective sweeps” that police may conduct in association with an arrest. Note that sweeps are distinct from searches incident to lawful arrest and are governed by different rules.

We begin with vehicle checkpoints. Checkpoints involve stopping cars randomly—or otherwise selecting cars to stop without any specific reason to believe that the drivers are intoxicated or otherwise breaking the law or transporting items subject to seizure. Accordingly, vehicle checkpoints can be permissible only if the Court allows police seizures of persons and property without even reasonable suspicion, much less probable cause. The question is whether such seizures are “reasonable” under the Fourth Amendment.

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In the next case, the Court considered whether the holding of Michigan v. Sitz—permitting roadway checkpoints to look for drunk drivers–allows police to conduct random (suspicionless) stops of vehicles to check whether they contain illegal drugs. While a checkpoint for “drugged” drivers would almost surely have been permissible for the same reasons that the Court permitted drunk driving checkpoints, the question of a checkpoint for contraband or other evidence of crime proved more controversial.