Six other employees of the center had been pulled out of an airport boarding line a month earlier. Since all had purchased their tickets separately under their own names, it was plain that the Center for Constitutional Rights staff were on some kind of list. Readers familiar with the workings of bureaucracies will immediately recognize the clanks, squeaks and grinds of cumbersome government machinery getting into gear.

Olshansky and her colleagues are, apparently, not alone. For months, rumors and anecdotes have circulated among leftwing and other activist groups about people who have been barred from flying or delayed at security gates because they are "on a list."

But now, a spokesman for the new Transportation Security Administration has acknowledged for the first time that the government has a list of about 1,000 people who are deemed "threats to aviation" and not allowed on airplanes under any circumstances. And in an interview with Salon, the official suggested that Olshansky and other political activists may be on a separate list that subjects them to strict scrutiny but allows them to fly.