Orin Kerr writes:
My co-blogger David Post says that the Fourth Amendment allows air travelers to leave airport security screening areas if they wish without the TSA’s permission:
I am permitted to leave [the screening area] without TSA permission, whether they like it or not, because the Fourth Amendment’s prohibition on “unreasonable . . . seizures” gives me that permission. We have a word for this, too, in the law, when government agents don’t allow us to leave freely: ”being in custody.” And the government cannot put me in custody when they have absolutely no reason to believe that I have broken the law – the 4th Amendment prohibits that. Nor can they say “you’ve consented to being in custody when you go to the airport,” any more than they can say “you’ve consented to being in custody whenever you leave your home, so we can grab you and hold you whenever we damn please.”
It’s perhaps worth noting that the caselaw is generally to the contrary.
Read more on WaPo Volokh Conspiracy.