Mapp v. Ohio
In Mapp v. Ohio, 367 U.S. 643 (1961), the 6-3 U.S. Supreme Court imposed the exclusionary rule against the states. Specifically, the Court expanded the scope of the Fourth Amendment guarantee of the right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures... by requiring that the states do what the federal government had been required to do since 1914: exclude from criminal trials evidence that had been unconstitutionally obtained.
Mapp v. Ohio, did not purport to change the standards by which state searches and seizures were to be judged; rather it merely held that the "exclusionary" rule of Weeks v. United States, 232 U.S. 383, was applicable to the States. It was later, in Ker v. California, 374 U.S. 23 (1963), that the U.S. Supreme Court held that State searches and seizures are to be judged by the same constitutional standards as apply in the federal system.
Facts of the Case
Police officers in Cleveland, Ohio, had forced their way into the residence of one Dolly Mapp, searched her dwelling, and seized "certain lewd and lascivious books, pictures, and photographs...."This resulted in Mapp's conviction under an Ohio obscenity statute. The Supreme Court reversed her conviction, ruling that the Fourth Amendment guarantee is enforceable against the states "by the same sanction of exclusion as is used against the federal government." Since the evidence against Dolly Mapp had been obtained in violation of her right to privacy, it could not be used in a trial as part of the government's case against her. This is known as the exclusionary rule. In Mapp v. Ohio, the Supreme Court put the states on notice that if they convicted people on the basis of evidence unconstitutionally obtained, they could find the convictions overturned.