The FISA Amendments Act of 2008, also called the FAA and Foreign Intelligence Surveillance Act of 1978 Amendments Act of 2008, is an Act of Congress that amended the Foreign Intelligence Surveillance Act. It has been used as the legal basis for surveillance programs leaked by Edward Snowden in 2013, including PRISM.
Warrantless wiretapping by the National Security Agency (NSA) was revealed publicly in late 2005 by The New York Times and then reportedly discontinued in January 2007. See Letter from Attorney-General Alberto Gonzales to Senators Patrick Leahy and Arlen Specter, CONG. REC. S646-S647 (January 17, 2007). Approximately forty lawsuits have been filed against telecommunications companies by groups and individuals alleging that the Bush administration illegally monitored their phone calls or e-mails. Whistleblower evidence suggests that AT&T was complicit in the NSA's warrantless surveillance, which could have involved the private communications of millions of Americans. The Foreign Intelligence Surveillance Act makes it illegal to intentionally engage in electronic surveillance under appearance of an official act or to disclose or use information obtained by electronic surveillance under appearance of an official act knowing that it was not authorized by statute; this is punishable with a fine of up to $10,000 or up to five years in prison, or both. In addition, the Wiretap Act prohibits any person from illegally intercepting, disclosing, using, or divulging phone calls or electronic communications; this is punishable with a fine or up to five years in prison, or both.
Links to Law
Public Law (PL) 110–261 - FISA Amendments Act of 2008 (PDF)
50 U.S. Code Chapter 36 - FOREIGN INTELLIGENCE SURVEILLANCE - Cornell Law School.