Behavioral screening is a useful tool in deterring and preventing terrorist attacks. As I noted in this piece at Politico, a border patrol agent successfully used behavioral screening to stop the would-be Millennium Bomber. She noticed something “hinky” about a man driving south across the Canadian border. That “hinky” – fidgety and nervous behavior when asked routine customs questions – exposed a car full of explosives intended for the passenger terminal of Los Angeles International Airport.

Two items from the USA Today travel section highlight some mixed results with TSA behavioral screening. Today’s edition reports that behavioral screening, applied by Behavioral Detection Officers (BDOs) missed at least 16 people later linked to terror plots. On the other side of the equation, false positives can impose burdens on those who are nervous or upset for reasons other than terrorism aspirations.

The TSA Blog defended the program: “If you’re one of those travelers that gets frazzled easily (not hard to do at airports), you have no reason to worry. BDOs set a baseline based on the normal airport behavior and look for behaviors that go above that baseline. So if you’re stressing about missing a flight, that’s not a guaranteed visit from the BDOs.”

That would be reassuring if yesterday’s travel section hadn’t revealed that TSA screeners are keeping a list of those who get upset at intrusive screening procedures. “Airline passengers who get frustrated and kick a wall, throw a suitcase or make a pithy comment to a screener could find themselves in a little-known Homeland Security database.”

Of course, we can take comfort from the words of a TSA screener to security expert Bruce Schneier. “This isn’t the sort of job that rewards competence, you know.”