The Christian Science Monitor has an article that says political appointees in the Bush administration overrode objections to new rules regarding the treatment of prisoners of war put in effect soon after the events of September 11, 2001. It appears these individuals, up to and including Secretary of Defense Rumsfeld, rammed through changes that appear counter to the Geneva Convention. This, even after career military officers in the Judge Advocate General's Office strenuously objected to what they considered to be inappropriate, if not illegal, changes to prisoner treatment.
CSM persuasively makes the case that these changes set the stage for the abuse that occurred in Iraq.