International Judicial Monitor
Published by the International judicial Academy of the International Law Institute, Washington, D.C.
with circulation assistance from the American Society of International Law

Fall 2017 Issue




Jennifer Trahan
By: Jennifer Trahan, Associate Professor, Center for Global Affairs, New York University

On Thursday, December 14, 2017, the ICC’s Assembly of States Parties took the historic and significant decision, by consensus, to activate, effective July 17, 2018, the ICC’s jurisdiction over its 4th crime, the crime of aggression.   It was not through the jurisdictional interpretation of the crime of aggression amendment that many States Parties had favored; yet the decision nonetheless advances the rule of law and completes the ICC’s Rome Statute.

This decision has been a long time coming.  The crime of aggression is hardly a new crime, having historic roots.  It was of course famously prosecuted by the International Military Tribunal at Nuremberg (then termed “crimes against peace”).  But after the Nuremberg and Tokyo Tribunals, prosecution of the crime languished (along with the rest of the field of international justice) during the Cold War.  It resurfaced with the decision in 1998 at the Rome Conference, that the crime of aggression was one of the most serious crimes of concern to the international community (Rome Statute, arts. 1, 5.1) and one over which the ICC would have jurisdiction (Rome Statute, arts. 5.1, 12.1).  Only, states, in Rome, also agreed, in article 5.2, that there needed to be more time to negotiate the definition and conditions for the exercise of jurisdiction.  So, when the ICC first commenced operations, it did so with jurisdiction only over three crimes (genocide, crimes against humanity, and war crimes) having been activated.

After Rome, negotiations on the definition and conditions for the exercise of jurisdiction continued, first, at Preparatory Commission meetings, and then before the Special Working Group on the Crime of Aggression.  Work on the definition was essentially completed by 2008 (the end of the Special Working Group’s mandate).  Agreement on conditions for the exercise of jurisdiction, as well as various Understandings that accompanied the definition, were only concluded at the Kampala Review Conference (May 31 - June 11, 2010), on the shores of Lake Victoria.  Also agreed upon at the Review Conference was a delay mechanism, requiring 30 States Parties to ratify the amendment (now achieved, with 35 ratifications), 1 year’s passage after the 30th ratification (also now achieved), and one more vote or decision by consensus of the Assembly of States Parties (just now achieved).

This article will highlight a few key features of the definition and jurisdictional regime.

Definition of the Crime

There are various noteworthy features of the definition.  First, the crime has two different component parts—paragraph 8bis (para. 1) addresses the “crime of aggression,” which covers the conduct of the individual at issue.  Paragraph 2 then addresses the state “act of aggression,” which is the context in which the individual’s actions take place.  In this way, the crime is somewhat different from other ICC crimes (although they too require certain contextual elements in their “chapeaux”).

As to the crime, Rome Statute 8bis para.1 states:

For purposes of this Statute, “crime of aggression” means the planning, preparation, initiation or execution, by a person in a position effectively to exercise control over or to direct the political or military action of a State, of an act of aggression which, by its character, gravity and scale, constitutes a manifest violation of the Charter of the United Nations.

The words “planning, preparation, initiation or execution” derive from the London Charter of the Nuremberg Tribunal.  The next phrase is known as the “leadership clause,” which specifies that the crime is only committed only “by a person in a position effectively to exercise control over or to direct the political or military action of a State.”  This would cover only a very limited number of state actors.  Their conduct would then need to pertain to an “act of aggression” (described in para. 2) that, by its “character, gravity and scale,” constitutes a “manifest” violation of the UN Charter.  “Manifest” here means extremely clear; thus, de minimis incursions between two states would be excluded, as would all unclear cases (those falling within a grey area). 

As to the act of aggression, Rome Statute 8bis para. 2 states:

For the purpose of paragraph 1, “act of aggression” means 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. Any of the following acts, regardless of a declaration of war, shall, in accordance with United Nations General Assembly resolution 3314 (XXIX) of 14 December 1974, qualify as an act of aggression[.]

There then follows a list of covered acts, listed in subsections (a)–(g).

The first sentence basically tracks article 2.4 of the UN Charter.  The list of illustrative acts (a)-(g) come directly from General Assembly Resolution 3314 (1974).  Yet, each of these acts (a)-(g) would still only meet the definition of the crime (para. 1), if the act satisfies all other requirements (e.g. constituting a “manifest” Charter violation by its “character, gravity and scale.”)

Exercise of Jurisdiction

In terms of the jurisdictional regime, the most significant points to note are that the three ways that


an ICC investigation can be initiated under the current Rome Statute would all apply (UN Security Council referral, State Party referral, or the Prosecutor acting proprio motu). 

Yet, jurisdiction would be more restrictive than the current Rome Statute’s jurisdiction.  Two important features as to how jurisdiction would work for purposes of State Party referral and proprio motu initiation are:

  • Non-States Parties are completely exempt from jurisdiction (art. 15bis, para 5).  (This differs from the current Rome Statute, where nationals of non-States Parties are covered by jurisdiction if they commit a Rome Statute crime in the territory of a State Party.)

  • Even States Parties could opt out of crime of aggression jurisdiction by simply lodging an “opt out” declaration with the ICC’s Registrar (art. 15bis, para 4).  (As discussed below, the need to use this opt out has now diminished.) 

Why such jurisdictional carve-outs?  For better or worse, this was the agreement reached in Kampala. The carve-outs do not apply in the situation of Security Council referral, art. 15ter

There has, however, been a difference in interpretation as to how jurisdiction was being read, and that is why this December’s activation decision (taken after a year-long “facilitation” process) has been so complicated.  Namely, one reading (call it the Liechtenstein/Swiss/majority reading) was that after the activation decision, for purposes of State Party referrals and proprio motu initiation (art. 15 bis), then ALL States Parties could be subject to crime of aggression jurisdiction, absent their lodging an opt out declaration, but only also if either the aggressor or victim State Party also actively ratified the crime of aggression amendment.  The other reading (let us call it the UK/French reading), was that no State Party could be covered by the crime of aggression unless it had actively ratified the amendment.  This is an extremely restrictive reading of jurisdiction that those close to the negotiations seem to agree was not the majority understanding in Kampala. 

The activation decision taken on December 14 essentially takes the UK/French reading.  It states in relevant part:

[I]n the case of a State referral or proprio motu investigation the Court shall not exercise its jurisdiction regarding a crime of aggression when committed by a national or on the territory of a State Party that has not ratified or accepted these amendments.

Of course, only the ICC judges will be the ultimate arbiters of how they read their own jurisdiction, and the activation decision makes express reference to the judicial independence of the judges.

Quite a number of States Parties appeared disappointed with the UK/French reading (which made less sense given the “opt out” possibility – which inherently assumed most States Parties were “in” the jurisdictional regime).  Yet, States Parties also appeared to want to agree on activation of the crime.  Under the UK/French reading, jurisdiction much more depends on which States Parties actively ratify the amendment, so the crime’s ultimate jurisdictional reach very much depends on further ratifications.  The “opt out” possibility also now appears less significant, as fewer states are interpreted as being “in” the jurisdiction regime. 

Potential Significance

Some interesting questions to ask are:  How do we think this could impact the ICC’s docket?  And, will activation of the crime have any influence on state behavior?

As to the first question, because the crime is fairly restrictive in its definition (requiring a “manifest” Charter violation), and in its jurisdictional reach, it may actually be a number of years before anything that looks like a crime of aggression and meets jurisdictional conditions occurs.  Security Council referral will also be possible as of July 17, 2018, but in the first 15 years of the Court’s life, there have been only two such referrals covering the Court’s other 3 crimes.  In short, don’t expect this crime to clog the ICC’s docket.  This lack of immediate cases could also prove helpful in that it will provide the Office of the Prosecutor and Chambers some breathing room to develop expertise regarding the crime, which requires detailed knowledge of “jus ad bellum” rules in order to apply it properly.

As to the second question, this is actually the whole point:  that a state, when poised to decide whether or not to go to war, if it has concerns that it might be an illegal war, will have to second-guess itself just a little bit more, and maybe, just maybe, will decline to go to war on spurious claims.  While jurisdictional limitations reduce such potential deterrent impact, if such deterrence happens even once, then the crime will have achieved its purpose, potentially reducing combatant and civilian fatalities.  (Combatant casualties are casualties—even if not law of war violations; and civilian fatalities always occur, because we know that the myth of a “clean” war is just that.)  The goal of international criminal law is of course, not to bring cases, but to deter the commission of crimes in the first place.  

  • Jennifer Trahan is Chair of the International Criminal Court Committee of the American Branch of the International Law Association.  She has attended Preparatory Commission meetings on the  crime of aggression, the Special Working Group on the Crime of Aggression, the Kampala Review Conference, and the recent ASP in New York where activation was agreed upon.
ASIl & International Judicial AcademyInternational Judicial Monitor
© 2017 – The International Judicial Academy
with assistance from the American Society of International Law.

Editor: James G. Apple.
IJM welcomes comments, suggestions, and submissions.
Please contact the IJM editor at