Horton v. California

As a safeguard against random searches unsupported by strong evidence, the Fourth Amendment prohibits the police and other government agents from searching a person's home and possessions without a warrant. The warrant must be issued by a neutral judge for a search based on probable cause, and the warrant must specify the places to be searched and items to be confiscated.

However, the U.S. Supreme Court also acknowledges some exceptions to the Fourth Amendment's search and seizure clause, including finding evidence while in "hot pursuit" of a suspect, obtaining evidence when there is a strong possibility of its destruction, finding evidence during a frisk as part of an arrest, and discovering evidence in plain view while lawfully searching for items mentioned in a warrant. Items seized in such circumstances do not need to be listed in a warrant.

Coolidge v. New Hampshire and other cases helped define the "plain view" doctrine, which allows police to seize items they discover inadvertently because they are in plain view. The Coolidge ruling established three conditions that must be met in order for the seizure of evidence in this manner to be permissible. First, a warrant must authorize the initial search in the first place. Second, the incriminating character of the items must be immediately apparent. Third, the discovery of such items must be inadvertent. Arizona v. Hicks (1987) later reaffirmed that with probable cause, the police may seize evidence under the "plain view" doctrine.