In the case, On Lee v. U.S., 343 U.S. 747 (1952), the Court found that there is no violation of a suspect's fourth amendment right if a "friend" allows the police to listen in on a conversation. Electronic devices used to capture a conversation constitute a search under the fourth amendment, according to Berger v. New York, 388 U.S. 41 (1967). In Katz v. U.S., 389 U.S. 347 (1967), it was determined that any form of electronic surveillance, including wiretapping, that violates a reasonable expectation of privacy, constitutes a search. And, as stated in U.S. v. Karo, 468 U.S. 705 (1984), the warrantless monitoring of a beeper in a private residence violates the fourth amendment rights of individuals to privacy in their own homes and therefore cannot be conducted without a warrant. (The Court, however, reversed the decision on other grounds).