If the prisoners are ever released without being charged or tried (which won't happen because there's no evidence), they can each file a civil suit against the U.S. Government, each worth potentially hundreds of millions. I think this plays a role as well.

And if they are never released, then it can't happen?

Please don't tell me that it's a reasonable (legally or ethically) argument for keeping them imprisoned for decades.

It's the equivalent of keeping the neighbor's daughter in your basement because letting her out would get you into so much trouble.

Gitmo is already shockingly illegal or dangerously unethical; I don't see any interest by the US government to end it and take some of the heat for that.

As an American I've come the same conclusion. But it is a cowardly conclusion. We need to take our medicine and correct the wrong-doings of Gitmo. I don't really care if it costs a couple of hundred million dollars, that's chump change compared to the federal budget.

If a guy like Nixon can get a pardon so that the country can move forward, then we can certainly do the same for whatever ahats are culpable for setting up Gitmo in the first place. Pardon the military and politicians responsible for their misguided patriotism and then start treating these unfortunate souls like humans again as one small step towards making the US live up to its lofty ideals again.

The United States federal government cannot be sued unless it elects to allow the suit. This is not a real threat.

Look up "sovereign immunity".

Using the bully pulpit costs political capital, and nobody in the President's party wants him to waste political capital on Gitmo rather than healthcare, the economy, etc.