so every passenger must get equal treatment, except in extreme cases. That's why it's so hard to shift potential bad guys from the Department of Homeland Security's much larger databases to TSA's selectee and no-fly lists. As a libertarian, I agree that we should be very leery of forbidding people to fly without good reason. But requiring potentially high-risk travelers to undergo secondary screening (especially since we do some of this randomly, in any case) is hardly the end of the world. In fact, shifting to a risk-based approach to aviation security would likely mean increased security and lower costs, both for the TSA and especially lower wasted-time costs for most travelers. Under a risk-based approach, air travelers would be divided into three groups: lower-risk, ordinary, and higher-risk. The three groups would be treated differently, for very good reason. Lower-risk people would be those with active government-issued security clearances and anyone who joined a risk-based "trusted traveler" program by passing an FBI background check and getting a biometric ID card. These people would get streamlined processing at airports, similar to what existed pre-9/11. (Note that TSA's sister agency within DHS, Customs & Border Protection, operates a number of similar programs for U.S. citizens returning to this country, such as the recently expanded Global Entry program.) Higher-risk people would be those placed on an expanded selectee list and would be subjected to mandated secondary screening, including a body scan, backed up (if necessary) by a full body search. Now that terrorists