Olmstead v. United States   (1928)
Roy Olmstead was a suspected bootlegger and whose conversations were wiretapped without judicial approval. He was convicted from the evidence used from these tapes. The Supreme Court held that his Fourth Amendment rights were not violated when his telephone was tapped since only the physical examination of tangible objects – not listening into conversations – constituted a search.  Neither was the wiretap a violation of his Fifth Amendment protection against self-incrimination. This case was reversed by Katz v. U.S. (1967).

http://www.oyez.org/cases/1901-1939/1927/1927_493/