The United States Constitution, Fourth Amendment provides "[t]he right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated... " Privacy rights are triggered under the Fourth Amendment:
when a corporation has authorized an agent with direct authority to perform an electronic search of an employee’s e-mail account.
upon issuance of a subpoena duces tecum to bring electronic data (e-mails, files, etc.) including electronic metadata such as headers, directional information, and other such useful tracking data.
when the government is the primary actor.
during an archival search of e-mails on a corporation’s server.