The Electronic Communications Privacy Act (ECPA) of 1986 prohibits wire or electronic service providers from releasing information regarding customers' communications, unless the release is specifically authorized by a court order, subpoena, warrant, or other exception.
Improperly releasing such information can result in the provider being ordered to pay penalties. However, ECPA provides a safe harbor for service providers that improperly release information in good faith reliance on a court order, subpoena, or warrant.