The starting point for this exploration of the mens rea of the crime of aggression is its elements. The elements are an official ICC document clarifying the culpable mental state that applies to each aspect of the conduct, consequences, and circumstances constituting the crime. They are meant to “assist the Court in the interpretation and application” of the Rome Statute.
The first and still the most intrepid scholar to brave the elements was Professor Roger Clark. As a diplomatic representative for Samoa, he played a leading role in the drafting of the elements. Clark later wrote a paper in 2001 about this exercise — he called it anthropology of treaty-making — which also amounted to an elaboration on the work of the Preparatory Commission. His 2008 article, published in the New Zealand Yearbook of International Law, examines the way the elements of crimes were employed by the judges in the early jurisprudence of the ICC. In an article published just before the ICC Review Conference, Clark writes about negotiating the elements of the fledgling crime of aggression. This 2009 paper includes a revealing, if brief, discussion of the mens rea of the crime.
Two other sources are foundational to this analysis of the mens rea of the crime of aggression. In April 2009, as the work of the Special Working Group on the Crime of Aggression (“SWGCA”) was wrapping up, a small cadre of legal experts and diplomats was invited to an informal retreat in Montreux by the Swiss Department of Foreign Affairs to draft the elements of the crime of aggression. Frances Angaddi, Greg French, and James Potter, legal experts and diplomatic representatives from Australia, contributed a chapter to the Crime of Aggression Library about this meeting. SWGCA Chair Christian Wenaweser and his team then based their 2009 Chairman’s Non-paper on the Elements of Crimes, the other foundational source, on the work of the Montreux group. With only minor changes, the elements of the crime of aggression conceptualized in Montreux became the official elements adopted alongside the definition and jurisdictional conditions of the crime at the 2010 Review Conference in Kampala. The work of Clark, Anggadi et al., and Chairman Wenaweser are, therefore, the starting points analyzing the elements of the crime of aggression and its defenses.