Dec 26, 2014:

Yesterday, the National Security Agency (NSA) released surveillance documents in response to an American Civil Liberties Union (ACLU) Freedom of Information Act (FOIA) lawsuit. The documents span a time frame of 2001 to 2013 and reveal cases of improper surveillance by the NSA on American citizens.

More:

• NSA Fesses Up To Improper Surveillance Of U.S. Citizens | The Huffington Post
• U.S. Spy Agency Reports Improper Surveillance of Americans | Bloomberg News
• Executive Order 12,333 – FOIA Lawsuit | ACLU
• The NSA Archive | ACLU