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. First circulated in the weeks after 9/11 as a counterterrorism tool, its details are shrouded in secrecy.
But, because the list is filled with inaccuracies and ambiguities, thousands of innocent, law-abiding Americans have been subjected to lengthy interrogations and invasive searches every time they fly, and sometimes forbidden to board airplanes.
It also has been a complete failure, and has not been responsible for a single terrorist arrest anywhere.