A highway checkpoint aimed at obtaining information from motorists regarding a past crime did not violate the Fourth Amendment. Officers here set up a checkpoint at the scene where a fatal hit-and-run had occurred a week earlier, stopping each vehicle for ten to fifteen seconds to hand the occupants a flier and ask whether they had witnessed the incident. As defendant Lidster approached the checkpoint, his van swerved and nearly hit an officer. The officer smelled alcohol on Lidster’s breath, and a field test showed that he was under the influence. He was arrested and successfully challenged the stop in the state appellate courts. The United States Supreme Court reversed, noting that the stop’s primary purpose was not to determine whether the occupants of the detained vehicles were committing a crime, but to ask them as members of the public to help solve a previous crime. Thus, the checkpoint did not violate the Fourth Amendment.