 As a newly emergent area of international law, one main concern about international criminal law’s respect for the rule of law has traditionally focused on whether it complies with the demand that individuals should have fair warning that certain kinds of behaviour are criminally prohibited and attract liability to punishment. A dramatic illustration of this problem is the Nuremburg Trials, where it was questionable whether all of the grievous wrongs for which Nazi defendants were tried were in fact criminally prohibited by international law at the time they were committed (Kelsen 1947: 171). One response to these concerns is to argue that the wrongs in question were so obviously evil, and the subjection of their perpetrators to criminal trial and punishment so clearly justified and predictable, that the obligation to give due notice did not have great weight (Luban 2010: 583–587). To a significant degree, this problem has now been addressed, both as a result of the Rome Statute of the International Criminal Court, which defines the crimes of genocide, crimes against humanity, war crimes, and the crime of aggression, and assigns jurisdiction to the International Criminal Court, and as a result of the evolution of counterpart norms in customary international law.