Here, by way of TPM.

When I tried to use the curb-side check in at the Sunport, I was denied a boarding pass because I was on the Terrorist Watch list. I was instructed to go inside and talk to a clerk. ...

I presented my credentials from the Marine Corps to a very polite clerk for American Airlines. One of the two people to whom I talked asked a question and offered a frightening comment: "Have you been in any peace marches? We ban a lot of people from flying because of that." I explained that I had not so marched but had, in September, 2006, given a lecture at Princeton, televised and put on the Web, highly critical of George Bush for his many violations of the Constitution. "That'll do it," the man said.

I like this policy. I don't want to be stuck next to no dirty hippie on a plane for four hours!