We have spent most of our time so far trying to understand the normative foundations of the rules of war and of international humanitarian law. We have said very little about war crimes trials against individual defendants. The question that arises is whether individual criminal accountability can be assigned for violations of international humanitarian law. This is a serious question, indeed, for international humanitarian law, with the exception of the ICC Statute, is largely customary. And yet it is often said that mere custom is not sufficient to be the basis of a criminal proceedings, especially against someone who is not a head of state and is merely a normal soldier – or a civilian, for that matter. We will take up this issue, among others, in this chapter as we investigate what would need to be shown in order for a soldier to be criminally liable for violating the rules of war and international humanitarian law.

The controversy over the 2003–4 Abu Ghraib prison abuses brings to light the question of whether it is regular soldiers who should be primarily prosecuted for war crimes and, if so, what sort of proof of guilty intent is needed in such cases. I wish to argue that individual soldiers can indeed be held legally accountable for such things as the torture of prisoners of war, although the better case will be against the leaders who ordered or allowed such abuse to occur.