The Privacy Control Act of 1986, also known as the Electronic Communications Privacy Act (ECPA), has been amended several times. Some of the amendments are quite significant in scope.
The ECPA itself was an update of the Federal Wiretap Act of 1968, which only focused on intercepting communications over telephone lines; it did not anticipate the rise of other types of digital and electronic communications, like email. The ECPA added rules to deal with these types of communications, and it has been amended in turn to help the law keep pace with changing technologies.
The first major amendment to the ECPA appeared in the Communications Assistance to Law Enforcement Act (CALEA) in 1994. CALEA requires telecommunications carriers and equipment manufacturers to design their equipment and services in order to allow lawful surveillance by law enforcement. Circuit mode equipment, packet mode equipment, facilities-based broadband Internet access providers and VoIP providers are all subject to CALEA.
The next major amendment appeared in the USA PATRIOT Act in 2001. The PATRIOT Act amended a wide range of laws related to law enforcement - not just the ECPA.
Perhaps the most well-known change the PATRIOT Act made to the ECPA was in PATRIOT Act Section 206. Known as the "roving wiretap" provision, Section 206 allows law enforcement to tap every device a person uses with one approval from the Foreign Intelligence Surveillance Court (FISC). The "National Security Letters" program, also created by the PATRIOT Act, also amends the ECPA by allowing law enforcement to demand telecom records without court approval at all.
When the PATRIOT Act was reauthorized in 2006, its changes to the ECPA were reauthorized as well.
Finally, the FISA Amendments Act made significant changes to the ECPA's provisions by changing the legal basis for many electronic surveillance programs. For instance, it allows the Attorney General and the Director of National Intelligence to jointly authorize the surveillance of non-U.S. persons for a limited time period (no longer than one year).