In response to a Freedom of Information Act request, the CIA acknowledged the existence of Area 51, a secretive U.S. Air Force facility in Nevada and a subject of various UFO, and other, conspiracy theories.

The Freedom of Information Act, 5 U.S.C. § 552, is the United States federal freedom of information law that requires the full or partial disclosure of previously unreleased or uncirculated information and documents controlled by the U.S. government upon request. The act defines agency records subject to disclosure, outlines mandatory disclosure procedures, and includes nine exemptions that define categories of information not subject to disclosure. The act was intended to make U.S. government agencies' functions more transparent so that the American public could more easily identify problems in government functioning and put pressure on Congress, agency officials, and the president to address them. The FOIA has been changed by both the legislative and executive branches.