On the other hand, it's difficult to see what purpose is served by a domestic no-fly list. If government officials have concrete evidence that an American person is engaged in terrorist-related activities, then the government should be doing a lot more than putting that individual on a no-fly list.

They should be actively investigating the individual, tapping his phone, reading his email, monitoring his financial transactions, and generally gathering the evidence required to either clear his name, deport him, or arrest him.

If, on the other hand, the government doesn't have enough evidence of terrorist ties to justify starting an investigation against an individual, then it's unreasonable, not to mention a waste of law enforcement resources, to ban him from flying on airplanes or subject him to heightened scrutiny every time he goes to an airport.

The sheer number of people on the selectee list and the high rate of false positives may be one reason that screeners do a legendarily bad job finding simulated weapons in security tests. The resources now spent on screening tens of thousands of selectees--most of whom turn out to be false positives--would be far better spent on additional FBI agents to do in-depth investigations of people with actual terrorist ties.