International Court Ruling on the Environment, Summary
July 28, 2025
by William P. Meyers

Site Search

Popular pages:

OBLIGATIONS OF STATES IN RESPECT OF CLIMATE CHANGE

I sat down to write a blog in the recent opinion issued by the International Court of Justice on its decision that nations are obligated to protect the environment. The decision was announced July 23, 2025. The New York Times article on it is perhaps four pages long. I thought I should read the court opinion before writing my own opinion. To my surprise the opinion is 140 pages long. So instead of connecting it to the work to create a Global Environmental Protection Agency, here I am going to do the best I can to summarize those 140 pages. Then I will do a separate blog on how this proves the need for GEPA. Note I have used the word "nation" where the Court usually uses the word "state." [numbers in brackets refer to page numbers in the English document]

The Court claimed and justified jurisdiction to give the advisory opinion. The General Assembly of the United Nations sought the Court's opinion in its resolution 77/276 adopted on March 29, 2023. It listed prior resolutions of the UN on the environment, including the United Nations Framework Convention on Climate Change (UNFCCC), the Kyoto Protocol, and the Paris Agreement. [1-7]

It notes with "profound alarm" that greenhouse gas emissions continue to rise. It notes with "utmost concern" the Intergovernmental Panel on Climate Change that human-generated greenhouse gases are "unequivocally the dominant cause of global warming." This has caused "widespread adverse impacts" and these will be an increasing threat.

The history of attempts to influence the Court is covered. [9-14] A list of persons giving statements to the Court is given [14-26]

Jurisdiction of the Court is discussed. [27-29]

The context of resolution 77/276 is discussed, which basically gives a history of U.N. efforts to protect the environment. [29-34] The scientific background is discussed at length, much of it from IPCC reports. [34-39]

The scope and meaning of the General Assembly's request for an opinion are discussed at length. [40-45]

The argument for obligating nations (states) "in respect of climate change" is based on the Charter of the United Nations. "Climate change is a global problem which manifest itself in all these and other fields of concern for the United Nations," including economic, social, cultural and humanitarian issues. [46] Climate change treaties, the Law of the Sea, and other environmental treaties are briefly reviews. [46-48] It asserts that nations have agreed that they "have a duty under customary international law to prevent significant harm to the environment." [48-51] Other concepts entering the opinion are human rights, sustainable development, differences in national responsibilities and capabilities, equity (including intergenerational), the precautionary principle, and the polluter pays principles. It concludes all of these are applicable by the Court. [51-56] The conclusion on page 58 is that all of the above principles and agreements are applicable. [58]

The discussion of the obligations of nations in the climate change treaty framework starts on page 59. There have been differences in interpretation of the level of obligation to comply with treaties in the past. Articles 31, 32, 33 of the Vienna Convention on the Law of Treaties indicate nations should interpret the treaties in good faith. "While the UNFCCC and the Paris Agreement establish obligations on all parties, they recognize that such obligations may differ depending on parties' economic situations" [60] The UNFCCC also incorporates the precautionary principle. Also concepts of equity and intergenerational equity; also duty to cooperate. [61]

Discussion of the interrelationships of UNFCCC, Kyoto Protocol and Paris Agreement. It concludes the three climate change treaties are compatible and mutually supportive. [62-64] Obligations of nations under the UNFCCC include mitigation of greenhouse gasses, which is legally binding. Nations are obligated to mitigate the gasses; that is legally binding. [65-68] Nations are also obligated to adapt to climate change to minimize damage from it. [69-70] They are also required to cooperate and provide assistance (to less developed nations) with technologies that reduce or prevent emissions. [70-71]

Obligations under the Kyoto Protocol include certain states limiting or reducing emissions and adhering to binding gas emissions targets until 2012. "However, the Court notes that the absence of a new commitment period does not deprive the Kyoto Protocol of its legal effect." [71-72]

The Paris Agreement created new obligations similar to those discussed above. It also required parties to act with due diligence and provide financial assistance to impacted nations or people. It also set a temperature goal of keeping warming within 1.5 degrees C. of pre-industrial levels. [72-84]

It declares that nations have a duty to prevent significant harm to the environment. It cites, for instance, the case of Trail Smelter (U.S.A. v. Canada) which found, in 1965, "no State has the right to use or permit the use of its territory in such a manner as to cause injury by fumes in or to the territory of another or the properties or persons therein, when the case is of serious consequence and the injury is established by clear and convincing evidence." [85]

Defines "significant harm to the environment" risk, including to the climate system. This includes cumulative effects from a variety of behavior by a variety of nations. Best available science if currently found in reports of the IPCC. [86-87]

Dues diligence is the required standard of conduct. [87-93] Nations have a duty to cooperate. "The Court is of the view that the specific character of climate change requires States to take individual measures in co-operation with other States." [93-95] Discusses the relationship between climate treaties and customary international law. [95-96] There is a long section on state obligations under non-greenhouse gases climate treaties like the Ozone Layer Convention. [97-101] Considers the U.N. Convention on the Law of the Sea, including sea level rise. [101-108] Considers implications of international human rights law. Sees humans as having a right to a clean, healthy, sustainable environment. [108-116]

With that background, the Court considers the legal consequences of government acts and omissions that cause significant harm to the climate or environment. [116] Considers the applicable law. [116-120] Concludes: "responsibility for breaches of obligations under the climate change treaties, and in relation to the loss and damage associated with the adverse effects of climate change, is to be determined by applying the well-established rules on State responsibility under customary international law."

A determination was made of the responsibilities of nations. Some participants argued that the conduct of private actors resulting in emissions is not attributable to nations, but the Court ruled that states may be responsible due to a lack of due diligence or failing to take legislative measures. The Court concluded that while causal links can be complex, they can be identified. [120-126]

The Court then considers the legal consequences of wrongful acts. It makes clear that a nation failing to fulfill its international obligations is not excusable. Nations have a duty to cease wrongful actions. "The duty of cessation may also require States to employ all means at their disposal to reduce their GHG emissions and take other measures in a manner, and to the extent, that ensures compliance with their obligations." [126-130]

The decision of the Court goes from page 130 to page 133. After finding that it has the jurisdiction to give this advisory opinion to the United Nations, it answers in brief the questions from the General Assembly. Nations in the UNFCCC are obligated to adopt measures to mitigate greenhouse gas emissions. Parties to the Kyoto Protocol must comply with its provisions. Parties to the Paris Agreement are obligated to act with due diligence to achieve its temperature goal. But more generally international law obliges all nations to prevent harm to the environment, protect it from greenhouse gas emissions, and uphold other environmental treaties on ozone, biological diversity, and desertification, and human rights to a healthy earth.

"Is of the opinion that a breach by a State of any obligations identified in response to question (a) constitutes an internationally wrongful act entailing the responsibility of that State. The responsible State is under a continuing duty to perform the obligation breached. The legal consequences resulting from the commission of an internationally wrongful act may include the obligations of: (a) cessation of the wrongful actions or omissions, if they are continuing; (b) providing assurances and guarantees of non-repetition of wrongful actions or omissions, if circumstances so require; and (c) full reparation to injured States in the form of restitution, compensation and satisfaction, provided that the general conditions of the law of State responsibility are met, including that a sufficiently direct and certain causal nexus can be shown between the wrongful act and injury."

The ruling was unanimous. However, some judges added additional opinions.