Olmstead v. United States
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, conducted by federal agents without a search warrant with recordings subsequently used as evidence, constituted a violation of the target’s rights under the Fourth and Fifth Amendments of the U.S. Constitution.
Source: Wikipedia — Olmstead v. United States (CC BY-SA 4.0)