The Gambia v. Myanmar:
A reflection on the consequences of serious breaches of peremptory norms before the ICJ
By Luciano Pezzano & Diego Enrique Uribe Bustamante
Published on 31 March 2026
The Application of the Convention on the Prevention and Punishment of the Crime of Genocide (The Gambia v. Myanmar) is a historical case. For the very first time, a State brought another State before the International Court of Justice (ICJ) basing its standing solely on the erga omnes partes nature of the obligations arising from the Genocide Convention. The Gambia’s decision was rightly applauded, even as an exercise of the ‘Judicial R2P’ and the protection of common values of the international community as a whole. The oral proceedings on the merits concluded in January, and the ICJ began its deliberations on this very complex case.
The hearings and the publication of the written proceedings offer the opportunity to analyse the parties’ arguments. We found it astonishing that the case lacked references to the consequences of serious breaches of peremptory norms, as there was no mention of the commission of genocide as a serious breach of jus cogens, nor any discussion of its consequences in the hearing on the merits. For us, the commission of genocide is a serious breach of an obligation arising under a peremptory norm, and international law has particular consequences for such breaches. In this case, however, there was no significant discussion regarding this issue, as if genocide was just another ‘ordinary’ wrongful act.
The purpose of this post is to show how a jus cogens approach to the consequences of breaching these norms could have enriched The Gambia’s legal argumentation and, at the same time, offer some ideas about the current relevance of jus cogens in the international legal order. This is by no means a criticism of The Gambia’s legal team, whose titanic efforts to hold Myanmar accountable should be commended, but a series of reflections about the importance of a topic often overlooked in legal literature and judicial proceedings.
The ‘jus cogens paradox’
The legal nature of the prohibition of genocide poses a singular paradox for international lawyers. On the one hand, its peremptory character is universally accepted (as one of the authors of this post stressed before). On the other hand, however, no State (including applicants and intervening States in proceedings before the ICJ) seems to derive any particular consequence from that character. This is paradoxical because genocide is (with aggression) a paradigmatic example of a serious breach of an obligation arising under a peremptory norm, in accordance with Article 40 of the Articles on the Responsibility of States for Internationally Wrongful Acts (ARSIWA). Why can a State accuse another State before the ICJ of committing such a serious breach, but at the same time, not ask for particular consequences deriving from its peremptory nature? The Gambia v. Myanmar is not the exception in what seems to be a trend in the genocide cases before the ICJ.
The parties and participants in the case have reaffirmed the jus cogens nature of the prohibition of genocide. In the Memorial, The Gambia holds that ‘the prohibition of genocide has the character of a peremptory norm’ (para. 2.11). Myanmar did not deny it at any stage of the proceedings. The intervening States also recognise the peremptory character of the prohibition in their respective declarations: Belgium (para. 10), Ireland (para. 9), Maldives (para. 7), Slovenia (para. 26), Joint Declaration of Canada, Denmark, France, Germany, the Netherlands and the United Kingdom (para. 9).
However, none of the participants mentioned the consequences of that legal characterisation in the field of international responsibility. The declaration of intervention by Ireland illustrates this paradox: ‘the legal consequences for the State concerned of responsibility for such a serious breach and for a mere internationally wrongful act are the same (i.e. cessation, non-repetition and reparation)’ (para. 40).
A jus cogens approach concerning the consequences of State responsibility for the commission of genocide
Genocide is a serious breach of a norm that protects fundamental values of the international community as a whole, but it seems that such a breach would not entail any particular consequence. The paradox reflects a view in legal literature that the legal consequences of jus cogens are confined to the law of treaties and do not affect international responsibility.
We disagree with that view. We think that the paradox has an easy solution precisely in the rules of international responsibility. According to Article 41 of ARSIWA, serious breaches of peremptory norms have particular consequences under international law, namely: (1) the obligation to cooperate in order to bring the breach to an end, (2) the obligation not to recognise as lawful a situation created by the breach, and (3) the obligation not to render aid or assistance in maintaining that situation. Two decades after ARSIWA, in the commentaries to its Conclusion 19 on Jus Cogens, the International Law Commission (ILC) stressed the widespread acceptance of these consequences in the international community. These are duties upon all States and although they do not, per se, in and of themselves imply aggravation of the obligations upon the responsible State, they are consequences in the legal sense. A court can pronounce on them.
Consequently, we consider that there exists a protection gap in international judicial practice regarding State responsibility for the commission of serious breaches of jus cogens norms. Furthermore, this post argues that international courts—and the participants in judicial proceedings—should distinguish between violations of international law and serious breaches of peremptory norms. The existence of additional consequences for the responsible State, i.e., a regime of truly aggravated responsibility, remains a much contested topic in legal literature, and ARSIWA does not recognise it expressly (although one can argue that it is one of the ‘further consequences’ under Article 41(3)). Nevertheless, the very legal nature of jus cogens requires such a regime, and the commentaries to Article 41 of ARSIWA (p. 116) do not preclude further development of a more elaborate regime. As Judge Tladi affirmed in a recent article (p. 547):
Appropriate consequences must include reparations that recognise the seriousness of the breach and not only the consequences of the breach or harm caused by the breach. Serious breaches of jus cogens norms such as the prohibition on the use of force, the right of self-determination, the prohibition of genocide, the prohibition of crimes against humanity cannot attract the same consequences as breaches of other rules of international law.
In any case, the lack of consensus on the content and scope of the consequences of serious breaches is not, per se, an obstacle to seeking such consequences in a judicial proceeding before the ICJ. The Joint Application of Canada and the Netherlands against the Arab Republic of Syria under the Convention against Torture could serve as a useful example of the jus cogens approach. As it was stressed before, the Applicants asked the ICJ (para. 61):
to adjudge and declare that Syria has committed a serious breach of a peremptory norm of international law, due to its gross or systematic failure to fulfill its obligation under Article 2 of the Convention against Torture not to commit torture as well as to prevent its officials and other persons acting in an official capacity from perpetrating acts of torture, and determine the legal consequences thereof.
Moreover, by asking the ICJ about the consequences of serious breaches of jus cogens, States can contribute to the development of international law on the issue. Although the ICJ has a historical reluctance to refer to jus cogens, which Judge Tladi describes in a declaration as a conflation with the concept of erga omnes obligations (para. 37), it is also true that the rules on jus cogens have recognised the central role of the ICJ in the matter as provided in Article 66(a) of the Vienna Convention on the Law of Treaties. If more States insist on the consequences of serious breaches of jus cogens, the ICJ will have to pronounce on them.
The light at the end of the tunnel
Jus cogens played a small but significant role in The Gambia’s legal strategy regarding guarantees of non-repetition. According to Article 30 of ARSIWA, the responsible State is under the obligation to offer guarantees of non-repetition ‘if circumstances so require’, and the ICJ is traditionally reluctant to indicate such guarantees. In order to sustain its claim for guarantees of non-repetition in the case, The Gambia holds in its Memorial:
13.13 The character of the obligations breached, the seriousness of the breaches, and the risk of repetition are the three factors to consider when assessing whether assurances and guarantees of non-repetition are warranted. Since all are met in this case, the Court need not decide if those factors are cumulative or alternative.
13.14 Concerning the character of the obligations breached, the Court has already found the obligations under the Genocide Convention to be erga omnes partes while the “norm prohibiting genocide was assuredly a peremptory norm of international law (jus cogens)”. The seriousness of the breaches derives from the specific character of the obligations under the Convention; they have been amply evidenced in this Memorial. The risk of repetition must be assessed considering all the circumstances of the case, including the seriousness of the breaches, because even if the risk of repetition is minimal, quod non, assurances and guarantees of non-repetition are warranted when the prior violations are, as in this case, of exceptional gravity.
Without affirming that genocide is a ‘serious breach’ under the meaning of Article 40, one could argue that The Gambia implies it, since both the jus cogens nature of the prohibition of genocide and the seriousness of the breaches are central features in its argument. In its Counter-Memorial, Myanmar rejects The Gambia’s claim (para. 15.81):
this argument is circular and can be applied to all violations of the Genocide Convention. The fact that the obligations breached are those under the Genocide Convention does not automatically give rise to an order to provide assurances and guarantees of non-repetition. Thus, in the Bosnia Genocide case – a case where the Court found breaches of the obligations to prevent and punish genocide – it did “not consider that this is a case in which a direction for guarantees of non-repetition would be appropriate.”
An important distinction should be raised from Myanmar’s argument: in the Bosnia v. Serbia case, the ICJ did not find that Serbia was responsible for breaching the prohibition to commit genocide, but for not preventing it and punishing it. That finding had an important effect on the Court’s reasoning regarding the consequences of the wrongful act. Therefore, in The Gambia v. Myanmar, the Applicant is seeking the guarantees of non-repetition primarily as a remedy for the breach of the obligation not to commit genocide.
Here, the jus cogens approach could be useful against the Respondent’s argument: the breach of the obligation not to commit genocide is, in itself, a serious breach of a peremptory norm, it then satisfies the criteria set up by the ILC, and triggers the third State´s obligations under Article 41 of ARSIWA, different from Myanmar´s conflation with the separate prohibition of prevention and punishment of genocide, which does not constitute a peremptory norm (p. 697). The idea is implicit in The Gambia’s Memorial, but an explicit approach is a stronger position and better reflects both the character of the obligation and the seriousness of the breach.
Final remarks
Although first enshrined in the law of treaties, the notion of jus cogens acquires its true meaning in the law of responsibility. Christos Rosakis argued that the expansion of the functional scope of jus cogens beyond the law of treaties means the perfection of the international legal system (p. 19). Judge Cançado Trindade explained this view in his Concurring Opinion to the Inter-American Court of Human Rights’s Advisory Opinion on Juridical Condition and Rights of the Undocumented Migrants (para. 70):
The concept of jus cogens in fact is not limited to the law of treaties, and is likewise proper to the law of the international responsibility of the States. […] it is in this central chapter of International Law, that of the international responsibility (perhaps more than in the chapter on the law of treaties), that the jus cogens reveals its real, wide and profound dimension.
The reason is clear: if there are no particular consequences arising from the serious breaches of peremptory norms, what is the true meaning of jus cogens? Enforcing jus cogens requires not only the decision to invoke the responsibility of States breaching obligations erga omnes arising from peremptory norms, as The Gambia did, but also to ask the courts—especially the ICJ—for the consequences of those serious breaches.
The jus cogens approach we propose seeks to understand genocide as a serious breach of a peremptory norm, with consequences under the law of international responsibility. The approach seems obvious, but it is overlooked in legal literature and judicial proceedings. In times where the most fundamental rules of international law are at stake, we need to be clear about the consequences of breaching jus cogens. The current cases before the ICJ offer a singular opportunity to develop those consequences.