I think under the theory that until we hand him over to the Iraqis, he is a prisoner of war, and we can't allow him to be executed as a technical enemy combatant. Unlike the terrorists, he was a head of state. It's actually an interesting legal question for scholars. He is technically our prisoner, does the Iraqi government have international authority to have him. It's moot. He is getting hanged, but my bet this is what the legal argument is about.
good analysis.
Might come in handy.