Olmstead v. United States, 277 U.S. 438 (1928), was a decision of the Supreme Court of the United States, on the matter of whether wiretapping of private telephone conversations, obtained by federal agents without a search warrant and subsequently used as evidence, constituted a violation of the target’s rights under the Fourth and Fifth Amendments. In a 5–4 decision, the Court held that the Constitutional rights of a wiretapping target have not been violated. This decision was overturned by Katz v. United States in 1967.