Mapp v. Ohio

Mapp v. Ohio, 367 U.S. 643 (1961), was a landmark decision of the U.S. Supreme Court in which the Court ruled that the exclusionary rule, which prevents prosecutors from using evidence in court that was obtained by violating the Fourth Amendment to the U.S. Constitution, applies not only to the federal government but also to the state governments. 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 is applicable only to actions of the federal government into the Fourteenth Amendment's due process clause which is applicable to actions of the states. 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 a private lawsuit against the officers involved, either in trespass to recover damages or in replevin to recover their seized goods or property. This changed in 1914, 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. In an opinion written by Justice William R. Day, the Court reasoned that the Supreme Court had a constitutional duty to ensure federal courts excluded illegally obtained evidence: Over the next several decades, the Court generally held that this "exclusionary rule" only applied to cases in which federal law enforcement officers, not state officers, were involved in the illegal searches and seizures. In 1949, the Court confronted the issue of the exclusionary rule's application to states in the case of Wolf v. Colorado. The Wolf Court surveyed existing U.S. states and found that although 17 states had adopted the exclusionary rule of Weeks in their own state law, 30 others had rejected it. It therefore concluded that it was not a "departure from basic standards" of due process to allow states to introduce illegally obtained evidence in state trials.