Mapp v. Ohio

Mapp v. Ohio, 367 U.S. 643 (1961), is a landmark U.S. Supreme Court decision in which the Court ruled that the exclusionary rule, which prevents a prosecutor from using evidence that was obtained by violating the Fourth Amendment to the U.S. Constitution, also applies to the states.

The Supreme Court accomplished this by use of a principle known as selective incorporation. In Mapp, this involved the incorporation of the provisions, as interpreted by the Court, of the Fourth Amendment (which applies only to actions of the federal government) into the Fourteenth Amendment's Due Process Clause. On the matter of warrantless searches, the court cited Boyd v. United States and ruled, "It is not the breaking of his doors, and the rummaging of his drawers, that constitutes the essence of the offense; but it is the invasion of his indefeasible right of personal security, personal liberty, and private property."

Legal background

The Fourth Amendment to the U.S. Constitution provides: "The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated...." Until the early 20th century, Americans' only legal remedy in cases where law enforcement officers violated the Fourth Amendment was to sue the officers involved, either for trespassing to recover damages or via the replevin tort to recover their seized goods or property. This changed in 1924 when the U.S. Supreme Court unanimously ruled in Weeks v. United States that any evidence obtained by federal law enforcement officers in violation of the Fourth Amendment could not be used in federal criminal proceedings.

Over the next several decades, American courts generally held that this "exclusionary rule" only applied to cases in which federal law enforcement officers, not state officers, were involved in illegal searches and seizures. In 1949, the Supreme Court confronted the issue of the exclusionary rule's application to states in Wolf v.