The ACLU has every right to be concerned as the Govenment seeks to expand the no-fly list:

The Sept. 11 Commission wants the government to expand the no-fly list airlines now check to keep suspected terrorists off planes, consolidating as many as 12 secret lists maintained by different intelligence agencies. That worries the American Civil Liberties Union, which has already sued the government, saying the airlines' effort to keep terror suspects and other dangerous people off planes ensnares innocent passengers and subjects them to unnecessary searches and delays. Also, the government provides no way for those wrongly named to get themselves removed.

"Right now, if you're on the list, you're in a no-fly jail. There is now no way out of this," said Barry Steinhardt, the director of the ACLU's Technology and Liberty Project.