“No public explanation for the deal (Omar Khadr plea bargain) has ever been given”
True. We know the US has been trying to get K to plead guilty for a deal on the sentence at least since 2007. One reason might be that when he pleaded guilty he gave up appeal rights, keeping the case out of their regular courts, which might have seen it the same way ours did, illegal. He promised not to sue the US for abuse, contradict the confession, or talk about anything for money. He agreed to be interrogated for a year, maybe to implicate other detainees. The US can keep people in Gtmo indefinitely, regardless of trials or results by saying they are a risk. The deal is a win win for both sides.