The ICJ Advisory Opinion - Obligations of States on Climate Change: Part Two - Legal Consequnces of Breaching Obligations

In this second part, I present a summary of the portion of the seminar dealing with the second question: What are the legal consequences, if any of breaching these obligations? I will also contextualize the AO from the standpoint of a developing country negotiator at the many COPs and Subsidiary Body meetings in which I have served as a national delegate over the years.

As mentioned in part one, this three-part series is based on the proceedings of a Seminar entitled: The ICJ Advisory Opinion on Climate Change and What it Means for Malaysia, organized and conducted by Environmental Lawyer, Mr. Kiu Jia Yaw and his team at Kiu&Co.

The Second Question to the ICJ

If you recall, the second question posed to the ICJ read: What are the legal consequences under these obligations for States where they, by their acts and omissions, have caused significant harm to the climate system and other parts of the environment, with respect to: 

i. States, including, in particular, small island developing States, which due to their geographical circumstances and level of development, are injured or specially affected by or are particularly vulnerable to the adverse effects of climate change? 

ii. Peoples and individuals of the present and future generations affected by the adverse effects of climate change?

Findings on Legal Consequences of Breach 

The ICJ found that States could be held responsible for any breach of these obligations, and that such an occurrence would constitute an internationally wrongful act entailing the responsibility of that State.

In making this determination, the ICJ found that causation of damage is not a requirement for the determination of responsibility as such. For a finding of State responsibility, what is required is an internationally wrongful act and its attribution to a State, regardless of whether the act actually causes harm or not. Causation, the ICJ concluded, is a legal concept that plays a role in determining reparation.

The Erga Omnes nature of the Obligations

If States can indeed be held responsible for violations of their obligations, a key question that arises is the question of who may deem themselves impacted by such a violation and bring a case against the State in question. In this regard, the ICJ opined that All States and parties (as the case may be) have a legal interest in the protection of the main mitigation obligations set forth under customary international law and the climate change treaties. As such, the Court determined that these obligations are of an erga omnes character (that is, an obligation owed to everyone, as opposed to just a specific person or party). It follows, therefore, that the responsibility for breaches of such obligations, such as climate change mitigation obligations, may be invoked by any State when such obligations arise under customary international law, or party to the treaty, when they arise under climate change treaties.

Duty of Performance and Cessation

The Court opined that occurrence of a breach could not be used to justify nullifying any Parties’ obligations. In a historical example, when some Annex I Parties to the First Commitment Period (2012-2018) of the Kyoto Protocol found that they were not on track to achieve their emissions reductions targets, they simply ‘left’ the Kyoto Protocol, or, otherwise, decided not to announce an emissions reduction target to which they could be legally bound. Recognizing States’ propensity to avail themselves of legal loopholes, the Court clarified that a breach does not extinguish any State’s underlying duty of performance. So regardless of their compliance status, States have a continuing duty to perform their obligations. Additionally, under customary international law, a State responsible for an internationally wrongful act cannot continue to undertake the action, but instead, has a duty to immediately cease that act.

The Case for Reparation

Climate impacts can be severe and have far-reaching consequences. They are certainly not restricted to local property damage, but can ruin livelihoods, ravage entire industries and destroy national and even regional economies. To establish reparation, however, the Court determined that causation must be established between the wrongful act of a State (or group of States) and particular damage suffered by the injured State, or, in the case of human rights law, by the injured individuals. In cases where causation can be established, Art. 31 of the International Law Commission Articles on State Responsibility states that a responsible State is under an obligation to make full reparation for the damage caused by the internationally wrongful act. Full reparation can be in the form of restitution, compensation, and/or satisfaction (provided a sufficiently direct and certain causal nexus exists between the wrongful act and injury).

Implications of the ICJ’s understanding on the application of Lex specialis

In part one, I pointed out a key issue and a major flash point in the ICJ proceedings, the issue of Lex specialis.  In simple terms, it is the rule that a specific law should take precedence over a more general law when both apply to the same situation. It essentially means that when two laws conflict, the more specific one should be applied. In part one, I also described the sharp difference in position between, on the one hand, countries with high cumulative historical emissions and, on the other, developing, highly climate-vulnerable states.  

To see how these differences have played out, we need look no further than the negotiation and implementation of the legally-binding instruments (the Kyoto Protocol and Paris Agreement) under the United Nations Framework Convention on Climate Change (UNFCCC). Specifically, the negotiation of these instruments has consistently been plagued by the erosion of the key principles as contained in Article 3 of the Convention. Beginning with the Principle of Common but Different Responsibilities and Respective Capabilities (CBDR-RC), developed country negotiators have, at every turn, taken every opportunity to renounce, discredit and deemphasize principles such as responsibility for historical emissions, the polluter pays principle, the precautionary principle, and the rationale and operation of the Annexes 1 and 2 under the Convention.

These differences are also reflected in developed country Parties’ unwillingness to engage constructively on the obligation to provide the means of implementation (finance, technology transfer and capacity building) as contained in Article 4 of the Convention. 

The recently concluded (and highly contentious) negotiations on the New Collective Quantified Goal for Climate Finance (NCQG) highlight the funding gap between what is needed by developing countries to adequately address climate change (estimated at USD1.3 trillion) and the amount that Annex I Parties to the Convention finally agreed to mobilize (USD300 million).

The ICJ’s effective reinstatement of the entire body of customary international law, including other rules and principles, as contained in the Convention, as a source of applicable law when determining the obligations of States under international law to ensure the protection of the climate system, means that  treaties do not displace other rules and principles as lex specialis but rather coexist and inform each other within the broader international legal system. This important result, in my personal view, serves to  reset the fundamental role of the basic principles of the Convention and restore, at least from a legal perspective, the rationale for the preambles of virtually every Multilateral Environmental Agreement and Protocol. It is also a testament to the wisdom and tenacity of developing country negotiators who ensured that these important concepts serve as the foundation that frames our respective national obligations through the lens of our Common but Differentiated Responsibilities and Respective Capabilities.

This concludes part two of the three-part series on the the ICJs landmark advisory opinion on “the obligations of states with respect to climate change”. In part three, I will cover the portions of the seminar that examined the implications for Malaysia, and discuss the potential implications of the ICJ AO for the tone of the COP30 negotiations in Belem, Brazil.

Acknowledgement:

I would like to acknowledge the efforts and contribution of Mr. Kiu Jia Yaw and his excellent team at Kiu&Co for convening the Seminar entitled: The ICJ Advisory Opinion on Climate Change and What it Means for Malaysia, held at the Asian Institute of Chartered Bankers (AICB) on the 19th of August, 2025, on which this three-part series is based. Thank you Mr. Kiu. Your views and insights on the ICJ AO, and your clear and detailed explanations of the issues are deeply appreciated.