The Electronic Communications Privacy Act
is a United States law
The “electronic communication” means any transfer of signs, signals, writing, images, sounds, data, or intelligence of any nature transmitted in whole or in part by a wire, radio, electromagnetic, photoelectronic or photooptical system that affects interstate or foreign commerce, but does not include (A) any wire or oral communication; (B) any communication made through a tone-only paging device; (C) any communication from a tracking device (as defined in section 3117 of this title); or (D) electronic funds transfer information stored by a financial institution in a communications system used for the electronic storage and transfer of funds.
Title I of the ECPA protects wire, oral, and electronic communications
while in transit. It sets down requirements for search warrants that are more stringent than in other settings. Title II of the ECPA, the Stored Communications Act
(SCA), protects communications held in electronic storage, most notably messages stored on computers. Its protections are weaker than those of Title I, however, and do not impose heightened standards for warrants. Title III prohibits the use of pen register and/or trap and trace devices to record dialing, routing, addressing, and signalling information used in the process of transmitting wire or electronic communications without a court order.