Here's a weirdly compelling video of a guy declining to answer a Border Patrol agent's questions at a checkpoint 50 miles north of the Mexican border. He repeatedly asks, "Am I being detained?" and "Am I free to go?" -- questions the poor agent fights like hell to avoid answering.
Comments on the site skew pretty heavily against the motorist, who people seem to think is being rude. His manner is certainly brusque, but I nevertheless find it thrilling to watch someone bravely assert their civil liberties in the face of armed authority. I can sympathize with the B.P. agent, who's just trying to do her job. Too bad that pesky Bill of Rights sometimes gets in the way.