Delaware v. Prouse

Background

A Delaware patrolman pulled over a car on a public road in 1976 without seeing any traffic violation or suspicious conduct and said he stopped the vehicle only to check the driver’s license and the car’s registration. As the officer approached he smelled marijuana and seized it in plain view; the driver was later charged. The trial court suppressed the evidence, the Delaware Supreme Court agreed, and the U.S. Supreme Court took the case to decide whether such random stops are lawful.

Reasoning

The Court weighed the intrusion on a motorist’s privacy against the State’s interest in road safety. It explained that stopping and briefly detaining people is a “seizure” under the Fourth Amendment and must be reasonable. Reviewing prior decisions about border patrol roving stops and checkpoints, the Court concluded that stopping a car at the officer’s unfettered discretion to check papers is not a sufficiently productive method to justify the intrusion. The Court held that officers need at least articulable, reasonable suspicion to stop a particular vehicle, and it affirmed the suppression of the evidence in this case.

Real world impact

After this decision, routine, discretionary license-and-registration checks of randomly chosen vehicles are unconstitutional. States and police may still use less intrusive, non-discretionary methods—for example, clearly organized roadblocks or neutral, evenly applied selection rules—but individual officers cannot stop drivers at will to check documents. Law enforcement must rely on observed violations or objective standards to justify stops.

Dissents or concurrances

Justice Blackmun (joined by Justice Powell) emphasized that roadblocks and systematic, nonrandom checks remain permissible. Justice Rehnquist dissented, arguing the Court should defer to state safety judgments and allow random spot checks without empirical proof of ineffectiveness.