Originally Posted by studentff

IANAL, but my understanding is that TSA checkpoints as well as DUI checkpoints are Constitutionally "tolerable" because they are clearly marked at known and marked locations and people in theory have the ability to avoid them by turning around and not going through the checkpoint. TSA itself loves to claim that you consent to completing the search once you place your bag on the x-ray belt or enter the WTMD (or probably also the strip search machine), but that you can leave voluntarily at any time prior.

Gate searches are more of an ambush, particularly if the ambush is done in the jetway out of visibility of the gate area.