On February 13, 2009, the Special Working Group on the Crime of Aggression (SWGCA), a group set up under the treaty establishing the International Criminal Court (ICC), announced a historic breakthrough. After five years of deliberation, the panel proclaimed it had finally reached agreement on a draft definition of the crime of aggression. The treaty that set up the court, called the Rome Statute, provides for prosecution of that crime, but the framers of the Statute were unable to agree upon a definition. Prosecution of that crime was suspended until the Statute could be amended to include a definition. The Assembly of States Parties will take up the Working Group’s proposed definition at its Review Conference in May 2010 in Kampala, Uganda.
I suggest in this Article that the proposed definition would constitute a crime in blank prose—one that would run afoul of basic international human rights norms and domestic guarantees of due process in its disregard of the international principle of legality and related U.S . constitutional prohibitions against vague and retroactive criminal punishment. The argument in favor of criminalizing aggression is, in Reinhold Niebuhr’s felicitous phrase, “a logic which derives the possibility of an achievement from its necessity.” Proponents appear to believe it is necessary that the crime of aggression be defined; therefore, they believe, the crime of aggression is perforce capable of being defined. But necessity, moral or otherwise, does not imply juridical achievability. Repeated efforts to define aggression foundered throughout the twentieth century as continuing political and cultural differences among states have prevented the formation of a consensus. Strong and weak states have long been sharply divided over when the use of force is appropriate and whether their own military and political leaders ought to be prosecuted for such an offense. The high level of specificity needed to impose individual criminal liability as opposed merely to guide state conduct has therefore proven unattainable.