Some people, like Senator John Cornyn, are worried that a civilian trial of the 9/11 plotters could lead to their possible release. Adam Serwer of The American Prospect explains why that will never ever ever happen.
"The same legal rationale that could have been used to hold him indefinitely will be used to hold him in case of an acquittal. As I reported a few months ago, because the U.S.has declared war against al-Qaeda — and KSM is quite obviously a member of al-Qaeda — they can claim legal authority to detain him even post-acquittal, until the end of hostilities, under the authority granted by the Authorization to Use Military Force. The Bush administration considered doing this briefly with Osama bin Laden's limo driver, Salim Hamdan; but because it makes a mockery of the American system of justice, they decided against it. But the options don't actually end there.
"They have three sources of authority that would allow him to detain [KSM], one of which is the AUMF, because it directly cites the 9/11 attacks in its language — the people who planned the 9/11 attacks are combatants and are detainable under the AUMF," explains Ken Gude, a human-rights expert at the Center for American Progress. "Under the .000001 chance that they are acquitted, they will have that authority to detain them."
The attorney general could detain him as an "international terrorist" indefinitely, in renewable six-month periods, based on a provision in the PATRIOT Act. And if things really get desperate, they could detain him as someone who is in the United States illegally, pending deportation. Since no country is going to take a mass murdering terrorist, that detention will essentially be indefinite.
On the prospect of KSM being released, Gude shrugs, "It isn't even in the realm of possibility."
Seems pretty air-tight.