I believe the prisoners were transferred to Bagram from Guantanamo by the Bush Administration (when the court decided that Guantanamo prisoners should in fact have habeas corpus rights). The ACLU filed a FOIA request yesterday to try to get information regarding what is going on at Bagram. Here is just a snippet of that request (link to pdf of the FOIA request:
http://www.aclu.org/pdfs/safefree/bagramfoia.pdf):
"This Request seeks records pertaining to the detention and treatment of prisoners held at the Bagram Theater Internment Facility at
Bagram Airfield in Afghanistan ("Bagram"), including records concerning the process afforded these prisoners to challenge their detention and designation as "enemy combatants.
<snip>
Recent news reports suggest that the U.S. government is detaining more than 600 individuals at Bagram.
<snip>
Bagram prisoners reportedly receive an even less robust and meaningful process for challenging their detention and designation as
"enemy combatants" than the process afforded prisoners at the U.S. Naval Base at Guantanamo Bay ("Guantanamo") - a process the U.S. Supreme Court declared unconstitutional last year... Moreover, there is public concern that the U.S. government is holding many prisoners at Bagram, rather than at Guantanamo, specifically to avoid any judicial review of their detentions in U.S. courts."