The bill would repeal the Patriot Act entirely and repeal the FISA Amendments Act, as well as a landmark 2008 expansion of the Foreign Intelligence Surveillance Act.

Among those in attendance were famed Pentagon Papers leaker Daniel Ellsberg, NSA whistleblowers William Binney, J. Kirk Wiebe and Thomas Drake, retired CIA analyst Ray McGovern, former Justice Department trial attorney Jesselyn Radack and former FBI agent Coleen Rowley.

There is no sign of an end to the erosion of Constitutional liberties that began under George W. Bush after the 9/11 attacks and continues under Barack Obama, the group said Monday.

"The government chose in great secrecy to unchain itself," said Thomas Drake, who worked at the National Security Agency in 2001.