Is Aggression a Leadership Crime? Revisiting Nuremberg Principles

[Miguel Lemos is an Assistant Professor at the Faculty of Law, University of Coimbra]

On 28 February 2024, Ukraine’s Supreme Court decided that only persons who play a “decisive role” in an aggressive state policy and those “directing” aggressive military operations are “capable of committing the crime of aggression” (all references to the judgment of the Supreme Court can be found here). Although the leadership standard devised by the Supreme Court is “broader” than the leadership standard enshrined in the ICC Statute, it is “inevitable” to conclude that, according to the Supreme Court, the crime of aggression is a leadership crime.  

The Supreme Court endorsed this view even though Article 437 of the Ukrainian Criminal Code does not include any restrictions as to who can be considered a possible perpetrator of a crime of aggression. Importantly, in a separate opinion, a judge of the Supreme Court “reiterated” that Article 437 was “silent on the existence of a leadership requirement” and added that “valid international legal acts” also contained no restrictions as to who can commit aggression.

Whether aggression is a leadership crime is not only a question of theoretical importance but also of immediate practical relevance. This, because the proposal for the creation of a special tribunal for the prosecution of Russia’s aggression is still on the table, and several countries are currently considering domestic prosecutions for aggression.  

In this post, I argue that the notion that aggression is not a leadership crime under customary law finds strong support in the Nuremberg Principles which formed in the aftermath of the Second World War. As further explained below, neither the IMT Charter nor the IMT Judgment envisioned aggression as a leadership crime. Similarly, Control Council No.10 did not include a leadership requirement, albeit some judgments by American occupation tribunals (or NMTs) interpreted Control Council No.10 as enshrining a “shape or influence” leadership standard. As noted by Kevin Jon Heller, the idea that crimes against peace could only be committed by defendants who had the authority to influence Nazi policy originated with the NMTs.  

Of all of the Nuremberg legislation and jurisprudence, the IMT Charter and the IMT Judgment are particularly important. The principles of international law that can be fleshed out from these two documents were unanimously “affirmed” by the General Assembly of the United Nations in December 1946. As aptly noted by Antonio Cassese, the General Assembly intended to express its approval of “the general concepts and legal constructs of criminal law that could be derived from the IMT Charter and had been set out, either explicitly or implicitly, by the IMT”. 

In other words, this unanimous “affirmation” endowed the IMT Charter and the IMT Judgment with an outsized weight to determine the customary law existing, forming or crystalizing at the time. 

In relation to the IMT Charter, its relevant part (Article 6) provides no support whatsoever for the existence of a leadership requirement as an element of crimes against peace. Quite differently, just to mention one particularly salient feature of Article 6, an accomplice who participated in the formulation or execution of a common plan to commit aggression would be responsible not only for his or her own acts contributing to the plan, but also for all other acts performed by the leaders, organizers, instigators, accomplices, or any other person in the execution of the plan. This feature alone unveils the extensive scope of individual criminal responsibility for international crimes emanating from the IMT Charter.

The IMT Judgment was delivered a year after the adoption of the IMT Charter (all references to the IMT Judgment can be found here). It is also clear that, for the IMT, a leading role was not necessary to warrant a conviction for aggression. 

For example, it convicted Funk for “participat[ing] in the economic preparation for […] aggressive wars” even though he “was not one of the leading figures in originating the Nazi plans for aggressive war”, and it entered a conviction for aggression in relation to Dönitz even though he was a “line officer performing strictly tactical duties”. 

Also, as Carrie McDougall has noted, the IMT entered convictions for a crime of aggression in relation to Rosenberg – who was a “mere member of the Reichstag and a middling Nazi Party functionary” – and Raeder – who was responsible for carrying out Hitler’s directives, “not for formulating them”. 

Crucially, the IMT put forward the following two assertions: (1) “Hitler could not make aggressive war by himself. [His followers] […] are not to be deemed innocent because Hitler made use of them, if they knew what they were doing”; (2) “The relation of leader and follower does not preclude responsibility here any more than it does in the comparable tyranny of organized domestic crime” (emphasis added). 

These two assertions constitute an explicit rejection of a leadership requirement. For the IMT, any high, mid, or low-level individual who knew of the aggressive plan and contributed to it (a “follower” who provided “co-operation”) could be found guilty of aggression in the exact same terms that a follower in a normal criminal organization could be found guilty of the murderous plan initiated by the leader and to which the follower provided his or her cooperation.  

Finally, it is also worth bringing to the fore the following three statements of the IMT:

1. the “essence” of the IMT Charter is that individuals have international duties “which transcend” national obligations;
2. those who violate the laws of war “cannot obtain immunity”;
3. individuals are criminally responsible if they comply with orders which are “in violation of the International Law of war”. These statements convey the message that all individuals in the world (not only leaders) have an international duty not to commit the crimes proscribed by the IMT Charter, i.e. aggression, war crimes and crimes against humanity. Note that these three statements appear in a section of the judgment entitled “The Law of the Charter”, a section which essentially consists of considerations about the crime of aggression. 

In the final part of this section, the IMT also mentioned Article 8 of the IMT Charter which prescribed that “[t]he fact that the Defendant acted pursuant to order of his Government or of a superior shall not free him from responsibility […]”. This provision applied to all crimes of the IMT Charter. Thus, it encompassed orders to commit aggression, it implied a duty not to follow such orders, and it indicated that those who perpetrate aggression while following orders were criminally responsible for a crime of aggression. 

Considering all of the preceding, it is reasonable to argue that the law as it flows from the IMT Charter and the IMT Judgment is summarily encapsulated in Nuremberg Principles I, VI, and VII. These principles were adopted by the International Law Commission (ILC) in 1950 and were meant to encompass aggression, war crimes and crimes against humanity. As specifically adapted to the case of the crime of aggression, they prescribe: (1) “Any person who commits aggression is responsible for aggression”; (2) “Complicity in the commission of a crime [of aggression] […] is a crime under international law” (emphasis added). 

However, in a commentary to Principle VI, the ILC added that – according to its own understanding – the expression “waging of a war of aggression” referred “only to high-ranking military personnel and high State officials”. Together with the NMTs’ jurisprudence mentioned above, this allusion to highly placed individuals seems to be the driving force behind the leadership idea that consolidated within the ILC more than half-century later (here and here). 

In contrast to other commentaries, which the ILC firmly supported with citations from the IMT Judgment, this commentary is not supported by any word or sentence of that judgment. That is because no such word or sentence is to be found therein. The ILC was apparently aware of this. In a commentary to Principle VII, it said that the IMT “seems to have applied general principles of criminal law regarding complicity. […] [This] is corroborated by expressions used by the Tribunal in assessing the guilt of particular defendants”.

 This commentary is accurate, it applies across the board (i.e. to all crimes under international law recognized by the IMT Charter), and it is corroborated not only implicitly by the “expressions” used by the IMT while assessing guilt, but also more explicitly by the above-mentioned references that can be found throughout the IMT Judgment.   

In conclusion, according to the IMT Charter and judgment, any person who commits or is complicity in aggression is subject to criminal responsibility under international law irrespective of rank, status or position. 

Taking into account the aforementioned ‘customary law weight’ of the IMT Charter and IMT Judgment, the considerations put forward in this post are apparently sufficient to infer that a customary law leadership requirement did not exist, formed or crystalized in the aftermath of the Second World War. 

Such considerations also support four final remarks. First, they serve as support for the argument that Ukraine has acted in tune with international law when it carried out in 2016 the first successful prosecutions for aggression since Nuremberg and Tokyo and convicted two low-level Russian defendants for crimes of aggression. Secondly, they support the argument that the numerous nationals laws in Eastern European countries which criminalize aggression without a leadership requirement are similarly attuned with customary law. Thirdly, they suggest that the leadership standard embodied in the ICC Statute does not (yet) correspond to customary law. 

Finally, they might encourage states which are currently considering domestic prosecutions for aggression and/or the creation of a special tribunal to prosecute Russia’s aggression to ponder whether they want to follow in the footsteps of the leadership requirement enshrined in the ICC Statute or to give a renewed impetus to what is arguably the true, albeit somewhat forgotten, customary law on the matter.