Paperwight's fair shot brings up an interesting catch 22, one that I'm sure the current administration, between torture advisory sessions, has thought about in great detail:
The post begins with the story of someone who was to be deported because he couldn't prove his U.S. citizenship. (In fact, he was born in the U.S.)
A worse problem is that under the Military Commissions Act of 2006 we now have another, even more pernicious two-tier system. If you're accused of "materially supporting" "hostilities" against the US or someone on the US's side and believed not to be a citizen, you have no right to challenge your indefinite detention (including on the grounds that you're actually a citizen), and you'll wind up in a kangaroo court like those down in Gitmo, which will have the power to do a hell of a lot more than deport you.
Actually, it is happening here. We just aren't allowed to hear about it.