After the September 11 attacks , the federal government instituted a broad range of new measures to combat terrorism , including the passage of the Patriot Act . The ACLU challenged many of the measures , claiming that they violated rights regarding due process , privacy , illegal searches , and cruel and unusual punishment . An ACLU policy statement states : During the ensuing debate regarding the proper balance of civil liberties and security , the membership of the ACLU increased by 20 % , bringing the group 's total enrollment to 330,000 . The growth continued , and by August 2008 ACLU membership was greater than 500,000 . It remained at that level through 2011
September 11 attacks
September 11 attacks
American Civil Liberties Union