Usually you need things like evidence to actually hold people. I would guess that there is none. Real shame that a government can't just hold people, right? Just keep that in mind the next time the Democrats control the White House.
the French do it all the time..they can hold up to 3 years, without charging...and often do..but no, the US cannot do that...
Gee you would think capturing them on the battlefield fighting to kill you would be enuf evidence?
I would guess that we did have evidence of their guilt, but released them to the Brits as a public relations gesture of cooperation/amity/ and to help prop up Blair.