Since the Sept. 11 terrorist attacks, the demands of national defense have sometimes been at odds with the nation's civil liberties. During the two World Wars, the Cold War and now the War on Terrorism, the president's powers increase and civil liberties are curtailed in the interest of protecting the homeland. The courts, which normally protect civil liberties, step back and give the president leeway. When the war is over, efforts are made to restore the liberties that have been taken away, but this can take decades. NPR's Barbara Bradley reports.