Luxembourg recently became the fourth State Party of the International Criminal Court (ICC) to ratify amendments to the Rome Statute that were adopted in a historic consensus at the 2010 Review Conference of the International Criminal Court in Kampala, Uganda. The January 15, 2013, ratification brings the controversial amendments another step closer to entering into force. If the requisite number of states ratify the proposed amendments, the ICC’s jurisdiction would dramatically increase in scope, likely having profound global implications for current armed conflicts.

Although the Rome Statute included the crime of aggression within the Court’s jurisdiction at its inception, the Court has been unable to exercise its jurisdiction as the original Statute failed to define the crime or its jurisdictional boundaries. Article 5 of the Statute lists four crimes for which the Court shall have jurisdiction: the crime of genocide, crimes against humanity, war crimes, and the crime of aggression. The inclusion of the crime of aggression in Article 5, while lacking a functional definition and jurisdictional details, was part of a compromise reached during the negotiation of the Rome Statute in 1998. However, on June 11, 2010, the delegates of the Review Conference of the Rome Statute adopted amendments that included a definition of the crime of aggression and established conditions for the Court’s jurisdiction.

The amendments adopted in Kampala include Article 8 which defines the crime of aggression for the purpose of the Rome Statute. The text of Article 8(1) states that the crime of aggression must be conducted by a person effectively controlling the political or military action of a State and is “the planning, preparation, initiation or execution […] of an act of aggression which, by its character, gravity and scale, constitutes a manifest violation of the Charter of the United Nations.” The term “act of aggression” is defined in Article 8(2) bis as the “use of armed force by a State against the sovereignty, territorial integrity or political independence of another State, or in any other manner inconsistent with the Charter of the United Nations.” Notably, this definition refers back to the UN Charter throughout the text, reflecting compromises made to limit the scope of the definition.

The adopted amendments also include Article 15 bis and 15 ter, the conditions for the Court’s exercise of jurisdiction over the crime of aggression. Under these amendments, the rules concerning when the prosecutor may initiate his or her own investigation into a crime of aggression differ from the other crimes under the Court’s jurisdiction. According to Article 15 bis, for the crime of aggression, the prosecutor could only open an investigation proprio motu, or one based on a state referral of a situation, after ascertaining whether the UN Security Council has made a determination of an act of aggression committed by the state concerned. If the Security Council has made such a determination, then the prosecutor may initiate the investigation. If the Security Council has not made such a determination within six months of the date of notification, then the prosecutor may commence the investigation only if the Pre-Trail Chamber has authorized it and the Security Council has not decided against recognition of an act of aggression.

The idea of a crime of aggression, while treated as a novel idea by many States Parties to the Rome Statute, is not at all a new concept within international law. Article 1 of the 1928 Kellogg-Briand Pact, known as the General Treaty for the Renunciation of War, declared, “The High Contracting Parties solemnly declare in the names of their respective peoples that they condemn recourse to war for the solution of international controversies, and renounce it, as an instrument of national policy in their relations with one another.” With the commencement of the Nuremburg Tribunal in 1950, an international court actually applied its jurisdiction to the crime of aggression though it used the term “crimes against peace.” The definition of crimes against peace adopted in the Nuremburg principles comprises “planning, preparation, initiation or waging of a war of aggression or a war in violation of international treaties, agreements or assurances.”

Along with the ideas promulgated at Nuremburg, the UN Charter, adopted in 1945, prohibited the use of armed force against another state in Article 2(4). Although international law had customarily protected the sovereignty of states, including their right to use armed force against another, the UN Charter, along with Nuremburg, suggest an evolving intent to limit the legitimate use of armed forces to situations of self-defense, although international humanitarian law has yet to place such strict limits in all cases. The new amendments to the Rome Statue would take steps toward reinforcing these limitations on the use of armed force and can be seen as an attempt to further the principles endorsed by Nuremburg—the end to global conflicts that result in mass casualties and the ability to hold individuals accountable for their actions in these atrocities.