jkhuggins

Here is the argument, from TSA's perspective.

TSA has two lists: the "no-fly" list of people who are not allowed to fly aboard commercial aircraft, and a "selectee" list of people who are only allowed to fly aboard commercial aircraft with additional screening performed at the checkpoint.

Instead of checking passengers against such lists at the checkpoint, TSA has pushed this activity back onto the airlines. When a passenger checks in for a flight and attempts to print a boarding pass (be it at home or at the airport), the airline relays the passenger's identifying information to The Powers That Be, who check the information against the master lists. If the name is not on the lists, the passenger can print the boarding pass. If the name is on the lists, the passenger is directed to airline personnel at the airport for further assistance.

So, when a passenger arrives at a checkpoint, how is TSA to know that the passenger is not on the no-fly list? In principle, the answer is "because the passenger has a boarding pass and a matching ID" --- because the existence of the boarding pass is sufficient evidence that the passenger is not on the no-fly list. This assumes, however, that the boarding pass and matching ID presented are both valid, and both match the passenger presenting them.

So, that's TSA's argument. I will leave the poking of holes in that argument as an exercise for the reader.