Got to point you to Bruce Schneier again.

Bruce Schneier, internationally renowned security technologist and author, argues that the “no-fly” list is an abomination that doesn’t really work. He characterizes it in this deadpan, reasonable and hilarious way:
“Imagine a list of suspected terrorists so dangerous that we can't ever let them fly, yet so innocent that we can't arrest them - even under the draconian provisions of the Patriot Act. This is the federal government's ‘no-fly’ list.”
His short article ends this way: “In a country built on the principles of due process, the current no-fly list is an affront to our freedoms and liberties. And it's lousy security to boot.”