The post-war trials of Axis, war criminals marked the last time that the crime of aggression was prosecuted. Today, the Special Working Group on the Crime of Aggression (SWG) is nearing agreement on a definition that will likely be adopted by the Assembly of States Parties to the International Criminal Court (ICC) - a prerequisite to the Court's exercise of jurisdiction over this, particular offense. In spite of decades of work, several key issues remain to be resolved before the definition is finalized. These include: The level of involvement of the Security Council in determining when a State commits aggressive acts, and whether a general or specific list of acts should be included in the definition of "aggression."
The delegates to the SWG differ as to whether the ICC may act absent a Security Council finding that aggression occurred. Arguments that the Security Council is the only body empowered to make this determination are misplaced. There is ample authority - sourcing from both international treaties and case law - that the General Assembly or, more appropriately, the International Court of Justice are competent to decide when States commit aggression. Leaving this decision exclusively in the hands of the Security Council would unnecessarily paralyze the investigation and the prosecution of criminal aggression.
The ability to effectively prosecute aggression will similarly be affected by the inclusion of either a specific or a general definition of State conduct constituting aggression. Proponents of a specific list of acts argue that it is required under the principle of legality - nullum crimen sine lege. Even if there was doubt at the outset of Nuremburg, the criminalization of aggression cannot be questioned today in light of the Kellogg-Briand Pact, the judgments of the post-WWII tribunals, the U.N. Charter, and General Assembly Resolution 3314. Defining aggression in terms of specific State acts would be an unnecessary step back, limiting the deterrent effect of the Court.
Keith A. Petty,
Sixty Years in the Making: The Definition of Aggression for the International Criminal Court,
31 Hastings Int'l & Comp. L. Rev. 531
Available at: https://repository.uchastings.edu/hastings_international_comparative_law_review/vol31/iss2/1