The International Court of Justice (ICJ) in its Advisory Opinion on the Legal Consequences arising from the Policies and Practices of Israel (⁋274) delivered on 19 July, 2024 identified certain obligations Erga omnes arising from breaches of International Humanitarian Law (IHL) and Human Rights Law. In light of these obligations, the Court laid out the legal consequences arising from the breach of these obligations invoking duties to be observed by other States to not recognize or aid the assisting State, while cooperating to end the breach. Similarly, the ICJ on 9 July 2004, in its opinion on the Legal Consequences of the Construction of a Wall (⁋157-159) affirmed that the breach of Erga omnes obligations arising from International Humanitarian Law gave rise to the correspondent duties upon all States, the duties of non-recognition, non-assistance, and cooperation.
Recently, in its advisory opinion dated 23 July 2025 on the Obligations of States in Respect of Climate Change (⁋439-443), the ICJ has recognized the Erga omnes character of certain rules arising in relation to climate change. However, unlike earlier cases, the Court is silent on the duties of non-recognition, non-assistance, and cooperation. This article will first endeavor to outline the duties of non-recognition, non-assistance and cooperation rooted in Article 41 of the ILC Articles on the Responsibility of States for Internationally Wrongful Acts, 2001 (ARSIWA). It will then turn to the separate opinions of Judge Tladi, which caution against the misapplication of Erga omnes obligations by the International Court of Justice. Finally, it will address the inconsistencies within the Court’s jurisprudence and propose a coherent framework for reconciling these principles.
Erga omnes Obligations, Jus cogens Norms, and the Consequences of Breach under ARSIWA
To arrive at an understanding of the status that Jus cogens norms and obligations Erga omnes hold, their respective origins must be looked at. These concepts were formulated from the same post-Second World War shift towards recognizing community interests in international law. The origin of Jus cogens norms can be traced back to doctrinal debates in the 1930s to protect certain community values, marking a shift from the traditional bilateralism that characterized much of international law. These norms were subsequently codified under Article 53 of the VCLT representing rules which override any treaty or law signed between State parties. Peremptory norms of general international law, or Jus cogens norms, are fundamental principles of general international law from which no derogation is permitted. They are universally binding on all States, irrespective of consent, and prevail over conflicting treaty or customary rules. Some examples include (see page 208) – the prohibitions on genocide, slavery, and apartheid.
Obligations Erga omnes were first articulated in the Barcelona Traction judgment in 1970 as duties owed to the international community as a whole. The Court provided a non-exhaustive list of Erga omnes obligations, including prohibitions on aggression, genocide, slavery, racial discrimination, and protections for basic human rights. Subsequently, in the East Timor judgment (see ⁋29), the ICJ articulated the right of self-determination as an obligation Erga omnes. All states can be held to have a legal interest in the protection of these obligations Erga omnes. The extent to which obligations Erga omnes can be divorced from Jus Cogens norms is minimal, with most of the obligations outlined above having a peremptory status barring the potential exception of protections for basic human rights.
While all Jus cogens norms generate Erga omnes obligations (see page 190), the inverse is not always the case; not all Erga omnes obligations attain the status and the non-derogable character of Jus cogens. Obligations arising out of climate change stands out as a clear practical distinction between Jus cogens norms and obligations Erga omnes. The responsibility to preserve the environment is cast on the international community as a whole, but this responsibility does not render treaties entered into between States as void, distinct from Jus cogens norms. In the recent advisory opinion on Climate Change (⁋445), the ICJ articulated the legal consequences arising out of breaching the obligations Erga omnes of preventing significant transboundary harm under Customary International Law and the United Nations Framework Convention on Climate Change (UNFCC) and Paris Treaties under Treaty Law.
These consequences are drawn from Article 42(b) of the ARSIWA pursuant to which, injured states can invoke legal responsibility if the obligation breached is owed to the group of States or the international community as a whole. Pursuant to Article 48(1)(b) on the other hand, any state, or state party may individually invoke the responsibility of a state alleged to be in breach of an obligation owed to the international community as a whole, irrespective of an injury to that particular state (see Climate Change Advisory Opinion (⁋442). These obligations are referred to as obligations Erga omnes. Additionally, a violation allows the injured state to seek cessation and a guarantee of non-repetition under Article 48(2). It also creates a duty on the responsible state to make reparation, in the interest of the injured State or relevant beneficiaries.
Articles 40-41 of the ARISWA pertain to the Chapter on Peremptory norms. Pursuant to Article 41(1) of the ARSIWA, a serious breach of a peremptory norm of general international law gives rise to the obligation of all States to cooperate, through lawful means, to bring the breach to an end. Article 41(2) further stipulates that no State shall recognize as lawful a situation resulting from such a breach, nor render aid or assistance in maintaining the situation created thereby. In light of this, the ICJ’s jurisprudence on legal consequences arising out of violations of obligations Erga omnes must be analyzed.
Incoherence in the ICJ’s Application of Article 41 ARSIWA to Erga omnes Obligations
In his declaration with respect to the Advisory Opinion on Climate Change, Judge Tladi (⁋36-37) draws attention to a troubling inconsistency in the Court’s treatment of Erga omnes obligations. He agrees with the Court’s conclusion that certain customary and treaty-based obligations relating to climate change amount to Erga omnes and Erga omnes partes character due to their connection with the global commons; however, he highlights an incoherence in the Court’s reasoning when compared to its 2024 Advisory Opinion with respect to the policies and practices of Israel. In the latter judgment (⁋279), the Court invoked the duties of non-recognition, non-assistance, and cooperation to end the breach, as part of the legal consequences arising out of a breach of Erga omnes obligations. Contrary to this position, the advisory opinion on the obligations of States in respect of Climate Change does not invoke these duties under Article 41(1) and 41(2), not deviating from the provisions of the ARSIWA.
These inconsistencies create legal uncertainty, thus hindering the development of a doctrinal framework in international law. The string of advisory opinions beginning from the 2004 Wall Judgment obscures the distinction between Jus cogens norms and Erga omnes obligations and the Responsibility of States arising from their breach consequently. Article 41 of the ARSIWA contains the consequences of serious breaches of peremptory norms; a serious breach of an obligation is defined under Article 40 as a gross or systematic failure by the responsible State to fulfill the obligation.
A systemic failure is deliberate, patterned conduct by the State. The term ‘gross’ denotes the intensity of the violation, in other words, the scale and scope of the violation. Pursuant to the ARSIWA, the duties of non-recognition, non-assistance and cooperation are triggered when the breach of a peremptory norm amounts to a gross or systematic failure. Article 42 and 48 however, do not exhibit similar language requiring a serious breach amounting to a gross or systemic failure in fulfilling the respective obligation.
By treating the legal consequences arising from a breach of Erga omnes obligations under Article 42 and 48 as functionally equivalent to those arising from serious breaches of Jus cogens norms under Article 40 and 41, the Court risks blurring the distinction between the non-derogable principles of general international law with obligations that are owed to all States. They occupy distinct conceptual domains in international law, and conflating them would risk legal uncertainty in the consequences arising from breaches of Erga omnes obligations and peremptory norms.
The Court in its Advisory Opinion on the Policies and Practices of Israel provides no justification for invoking duties that are, upon an ordinary interpretation of the ARSIWA, limited to grave and serious violations of peremptory norms in cases where an Erga omnes obligation is violated. The Advisory Opinion on Climate Change would suggest that the Court accords greater normative weight to certain breaches of Erga omnes obligations that arise from IHL or Human Rights Law, than breaches of Climate Change obligations arising from UNFCCC, or Customary International Law (CIL).
The Proper Interpretation of ARSIWA
To acknowledge the distinction between legal consequences arising out of violations of Jus cogens norms and obligations Erga omnes, their specific origins in the international law of state responsibility is located. The duty of non-recognition was recognized by the ICJ in the decision on the Military and Paramilitary Activities in and against Nicaragua (see ⁋188), and further support for this duty can be evidenced from the UNSC’s resolution (see page 114) calling for all states to confer no legal validity upon the use of force by Iran to acquire territory in Kuwait. The duty not to render aid or assistance can be observed from the UNSC’s prohibitions to render aid to the illegal apartheid regime in South Africa, a violation of a now Jus cogens norm. The duty of States to cooperate through lawful means to bring to an end a serious breach reflects a progressive development of international law codified in the ARSIWA, a consequence that is unique to breaches of peremptory norms.
A framework to reconcile the incoherency in the ICJ rulings requires a determination of the interpretation accorded to the ARSIWA. To that end, the ordinary meaning to be given to the words, in its context, and in light of the object and purpose of the treaty must be looked at. First, Article 40, and 41 are clear that the ensuing duties only arise upon a serious violation of a peremptory norm of general international law. Further, the context can be gathered from the title of the Chapter which explicitly deals with peremptory norms. This interpretation is also consistent with the object and purpose of the treaty to attach State responsibility to breaches of international law. It is important to note that Article 41(3) allows other consequences to be attached to violations of this character in addition to the consequences drawn from Article 41(1) and 41(2).
On the other hand, there appears no confusion in the wordings of Articles 42, and 48, with their application being permitted upon a breach of an international law where an obligation is owed to the international community as a whole. Judicial reasoning must then apply these consequences consistently across subject areas, in line with the proper interpretation of ARSIWA. There seems to be no reason for courts to depart from this norm and arrive at an interpretation of State Responsibility that attaches duties of non-recognition and non-assistance to breaches of Erga omnes obligations not amounting to peremptory norms of international law.
Conclusion
The ICJ’s advisory opinions have historically played a significant role in the progressive development of international law. Nevertheless, as Judge Tladi has rightly observed in his Declaration, the Court must be wary of the legal and practical implications of its judgments, particularly with respect to the responsibilities and duties it attaches to breaches of international norms. The Court’s invocation of duties of non-recognition and non-assistance in contexts of IHL which occupy an Erga omnes character, but not in its Climate Change Advisory Opinion may reflect an implicit prioritization on the view that violations of IHL warrant a more stringent response than environmental harm. Such reasoning suggests the Court treats IHL norms as equivalent to Jus cogens, occupying a non-derogable space in international law.
Interestingly, in that light, the recent Advisory Opinion by the Inter American High Court on Climate Change recognized that the obligation to prevent irreversible harm to the environment and climate occupies a peremptory status under international law. The court’s reasoning ties into human rights, representing a dependence between the enjoyment of certain fundamental human rights and the preservation of the environment. Noting the progressive development of the international law on climate change, this calls into question whether breaches of obligations under climate treaties and customary international law can trigger heightened duties, specifically, those of non-recognition, non-assistance, and cooperation. These developments reflect the importance of the theoretical distinctions between obligations Erga omnes and Jus cogens norms. By rooting the interpretation of responsibilities arising out of Erga omnes and Jus cogens norms in the text of the ARSIWA, the ICJ can avoid blurring the lines between the two.
Kamal Nambiar is a third-year law student at NALSAR, Hyderabad.
Picture Credit: ICJ
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