In the
United States, there is no specific constitutional guarantee on the privacy of correspondence. The secrecy of letters and correspondence is derived through
litigation from the
Fourth Amendment to the United States Constitution. In an 1877 case, the
U.S. Supreme Court stated: No law of
Congress can place in the hands of officials connected with the
Postal Service any authority to invade the
secrecy of letters and such sealed packages in the mail; and all regulations adopted as to mail matter of this kind must be in subordination to the great principle embodied in the fourth amendment of the
Constitution. The protection of the Fourth Amendment has been extended beyond the home in other instances. Unlike other jurisdictions it does not protect foreigners abroad. In the Supreme Court case
California v. Greenwood, protections similar to those afforded to correspondence have even been argued to extend to the contents of
trash cans outside one's house, although it turned out to be unsuccessful. Like all rights derived through litigation, the secrecy of correspondence is subject to interpretation. By Supreme Court
precedent, rights derived from the Fourth Amendment are limited by the legal test of a "
reasonable expectation of privacy". ==See also==