Soldal v. Cook County

The plain view exception, or plain view doctrine, gives law-enforcement authorities right to conduct a warrantless seizure on probable cause. Thus if a police officer making a routine stop on a traffic violation happens to be talking to a driver and sees a marijuana cigarette on the dashboard, the officer can seize the illegal substance (and make an arrest) without recourse to a warrant.

The Supreme Court first established the plain view doctrine in Coolidge v. New Hampshire (1971). The plurality in that case held that law-enforcement officials would be authorized to make a warrantless seizure in accordance with three requirements. First of all, the officer must have entered the place where he makes the seizure legally. Secondly, he must be "inadvertent" in his discovery; that is, it should not be a situation in which he knew about the item beforehand and simply failed to obtain a warrant to search for it. And thirdly, it must be "immediately apparent" that the item to be seized is illegal or incriminating, so that no further search is required to make that determination.