Mapp V. Ohio

Mapp v. Ohio, 367 U.S. 643 (1961), was a landmark case in criminal procedure, in which the United States Supreme Court decided that evidence obtained in violation of the Fourth Amendment, which protects against "unreasonable searches and seizures," may not be used in state law criminal prosecutions in state courts, as well, as had previously been the law, as in federal criminal law prosecutions in federal courts. The Supreme Court accomplished this by use of a principle known as selective incorporation; in this case this involved the incorporation of the provisions, as construed by the Court, of the Fourth Amendment which are literally applicable only to actions of the federal government into the Fourteenth Amendment due process clause which is literally applicable to actions of the states.