International Court of Justice

Op 23 juli 2025 sprak de ICJ zich uit over reeds bestaande internationale verdragen, en gaf daarbij een authoritaire "opinion" over Obligations of State on Climate Change. Het gaat om verdragen waarin zeer veel landen partijen zijn, die voortaan dienen te worden uitgelegd volgens deze zienswijze, met de mogelijkheid dat het voor de ICJ wordt gebracht bij andere interpretatie, waarbij de uitslag nogal voorspelbaar is.

Het Akkoord van Parijs is een belangrijke, daarin wordt het temperatuurdoel op 1,5 ⁰C gesteld omdat dat het beste wetenschappelijke bewijs is en dat wil dit volgen; ook wordt afgerekend met de vrijblijvende verplichtingen waaraan NDCs moeten voldoen; ze moeten samen het temperatuurdoel halen. Een dankbare opdracht voor COP 30! Landen die geen partij (meer) zijn in dit akkoord moeten desondanks meedoen op grond van de (vele) andere verdragen waarin de landen verweven zijn.

Wanneer het temperatuurdoel wordt overschreden kunnen landen daarop worden aangesproken, elk voor hun aandeel (aan excessieve emissies) en wel door elk benadeeld land afzonderlijk. Bovendien wordt het tegengaan van klimaatverandering tot aan het temperatuurdoel gezien als preconditie aan het genieten van mensenrechten; zonder die preconditie dus geen mensenrechten en dus (vermoedelijk zonder al te veel omhaal qua bewijsvoering) is het mogelijk voor mensen om hierover zaken te starten. Het daarbij om de internationale mensenrechten.

This is a summary, with the same paragraph numbers, of the full Advisory Opinion

Obligations of States

Co-operation

§140. The duty to co-operate lies at the core of the Charter of the United Nations. Article 1 of the Charter commits States “[t]o achieve international co-operation in solving international problems of an economic, social, cultural, or humanitarian character”. [...] In view of the related practice of States, the Court considers that the duty of States to co-operate for the protection of the environment is a rule whose customary character has been established

§141. This duty to co-operate is intrinsically linked to the duty to prevent significant harm to the environment, because unco-ordinated individual efforts by States may not lead to a meaningful result. It also derives from the principle that the conservation and management of shared resources and the environment are based on shared interests and governed by the principle of good faith

§142. For these reasons, the Court considers that the duty to co-operate for the protection of the environment forms part of customary international law and can also serve as a guiding principle for the interpretation of other rules. It forms part of the most directly relevant applicable law.

Human Rights

§144. The protection of the environment and the protection of human rights have been generally recognized as interdependent since at least the Stockholm Declaration of 1972

§145. the Court considers that the core human rights treaties, including the International Covenant on Economic, Social and Cultural Rights (hereinafter “ICESCR”) of 16 December 1966 and the International Covenant on Civil and Political Rights (hereinafter “ICCPR”) of 16 December 1966, and the human rights recognized under customary international law form part of the most directly relevant applicable law.

Sustainable Development

§147. Given its continuous and uncontested universal recognition, the Court considers that the principle of sustainable development guides the interpretation of certain treaties and the determination of rules of customary international law, including the duty to prevent significant harm to the environment and the duty to co-operate for the protection of the environment.

§148. the principle of common but differentiated responsibilities and respective capabilities reflects the need to distribute equitably the burdens of the obligations in respect of climate change, taking into account, inter alia, States’ historical and current contributions to cumulative GHG emissions, and their different current capabilities and national circumstances, including their economic and social development. The principle of common but differentiated responsibilities and respective capabilities thus acknowledges, on the one hand, the historical responsibility of certain States and, on the other, that the measures which can be expected from all States with respect to addressing climate change are not the same.

Climate Change Framework

§174. [UNFCC + Kyoto + Paris]

§176. the Court will apply the rules of interpretation to be found in Articles 31 to 33 of the Vienna Convention on the Law of Treaties, which also reflect customary international law

§178. the key principles that permeate all three climate change treaties are those contained in Article 3 of the UNFCCC [...] common but differentiated responsibilities and respective capabilities, the precautionary approach or principle, sustainable development, equity and intergenerational equity.

• RvR: nuttiger term "intergenerational equity"
• RvR: zie ook §§147-158

§180. Article 3, paragraph 3, of the UNFCCC, provides that “[w]here there are threats of serious or irreversible damage, lack of full scientific certainty should not be used as a reason for postponing such measures”.

§183. the duty to co-operate is also identified as a principle within the climate change treaty framework

§191. Article 2 of the UNFCCC recognizes the authority of the COP of the UNFCCC to adopt “related legal instruments” in order to achieve its purposes.

UNFCC

§200. mitigation lies at the heart of the UNFCCC’s objective, which is to stabilize GHG concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system

• RvR: definitions of source, sinks

Kyoto Protocol

(...)

Paris Agreement

§224. the Court considers the 1.5°C threshold to be the parties’ agreed primary temperature goal for limiting the global average temperature increase under the Paris Agreement.

§235. the obligation to prepare, communicate and maintain successive NDCs is procedural in nature and an obligation of result.

§236. the failure to prepare, communicate and maintain successive NDCs, to account for them and to register them would constitute a breach of the above-mentioned obligations.

§242. the content of a party’s NDCs must, in fulfilment of its obligations under the Paris Agreement, be capable of making an adequate contribution to the achievement of the temperature goal [...] i.e. to hold the increase in the global average temperature to below 1.5°C

§244. In the Court’s view, such transparency and accountability provisions would be meaningless if the parties had unfettered discretion in setting their NDCs.

§245. in the exercise of their discretion, parties are obliged to exercise due diligence and ensure that their NDCs fulfil their obligations under the Paris Agreement and thus, when taken together, are capable of achieving the temperature goal of limiting global warming to 1.5°C above pre-industrial levels, as well as the overall objective of the “stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system”.

• RvR: see §224 for the 1.5 ⁰C threshold

§246. because of the seriousness of the threat posed by climate change, the standard of due diligence to be applied in preparing the NDCs is stringent (see paragraph 138 above). This means that each party has to do its utmost to ensure that the NDCs it puts forward represent its highest possible ambition in order to realize the objectives of the Agreement.

• RvR: anders ben je kwetsbaar onder de zorgplicht

§249. All NDCs prepared, communicated and maintained by parties under the Paris Agreement must, when taken together, be capable of realizing the objectives of the Agreement which are set out in Article 2.

• RvR: see §224 for the 1.5 ⁰C threshold

§251. The obligation that parties “shall pursue domestic mitigation measures” is substantive in nature. [...] the obligation to pursue domestic mitigation measures is an obligation of conduct and not an obligation of result

• RvR: dat lijkt me realistisch, je kunt worden afgerekend op een bijdrage aan te hoge totale uitstoot, maar je wordt niet als afzonderlijke partij afgerekend op het niet halen van je NDC. je drukken is strafbaar als anderen het niet goedmaken, en dat risico wil je beter niet nemen.

§261. As observed earlier in respect of the obligation to co-operate under the UNFCCC (see paragraphs 214-218), such obligations exist for States both under conventional international law, including Articles 7, 9 and 12 of the Paris Agreement, and customary international law.

Customary International Law

§273. The duty to prevent significant harm to the environment also applies to the climate system, which is an integral and vitally important part of the environment and which must be protected for present and future generations

• RvR: zie ook §§73-74 voor present/future generataions

§274. States are subject to the duty to prevent significant harm either where no harm has yet been caused but the risk of future significant harm exists, or where some harm has already been caused and there exists a risk of further significant harm.

§275. Whether an activity constitutes a risk of significant harm depends on “both the probability or foreseeability of the occurrence of harm and its severity or magnitude”

Wrongful Acts of States

§276. The Court is of the view that a risk of significant harm may also be present in situations where significant harm to the environment is caused by the cumulative effect of different acts undertaken by various States and by private actors subject to their respective jurisdiction or control, even if it is difficult in such situations to identify a specific share of responsibility of any particular State. States must assess the possible cumulative effects of their acts and the planned activities under their jurisdiction or control. Although such “activities may not be environmentally significant if taken in isolation, ... they may produce significant effects if evaluated in interaction with other activities”

§277. It is the sum of all activities that contribute to anthropogenic GHG emissions over time, not any specific emitting activity, which produces the risk of significant harm to the climate system. This does not mean that individual conduct leading to emissions cannot give rise to the obligation to prevent significant transboundary harm even if such activity is environmentally insignificant in isolation.

§279. the diffuse and multifaceted nature of various forms of conduct which contribute to anthropogenic climate change does not preclude the application of the duty to prevent significant harm to the climate system and other parts of the environment. This duty arises as a result of the general risk of significant harm to which States contribute, in markedly different ways, through the activities undertaken within their jurisdiction or control.

§280. States must fulfil their duty to prevent significant harm to the environment by acting with due diligence.

§281. due diligence requires a State to “use all the means at its disposal in order to avoid activities which take place in its territory, or in any area under its jurisdiction, causing significant damage to the environment of another State”

§282. rules and measures must regulate the conduct of public and private operators within the States’ jurisdiction or control and be accompanied by effective enforcement and monitoring mechanisms to ensure their implementation.

§283. where there is generally recognized scientific evidence that it is highly probable that significant harm will occur, the standard of due diligence will be more demanding for all States (see paragraph 138 above). Due diligence also requires States to actively pursue the scientific information necessary for them to assess the probability and seriousness of harm, in conformity with the common but differentiated responsibilities and respective capabilities principle.

§285. the Court notes that States need to pursue technical co-operation and knowledge-sharing initiatives.

§286. Where a risk can be addressed with readily available technologies, States are expected to use them. [...] the cost of the relevant technologies may be a crucial factor in determining what can reasonably be expected of a State, depending on its capabilities.

§290. when determining the appropriate measures to be adopted by a State, the principle of common but differentiated responsibilities and respective capabilities must be taken into account.

§292. While developed States, in the context of climate change, must take more demanding measures to prevent environmental harm and must satisfy a more demanding standard of conduct, the standard required in each case ultimately depends on the specific situation of each State, namely “all the means at its disposal” [...] the reference to available means and capabilities cannot justify undue delay or a general exemption from the obligation to exercise due diligence.

§294. “where there are plausible indications of potential risks”, a State “would not meet its obligation of due diligence if it disregarded those risks” and, in that sense, the “precautionary approach is also an integral part of the general obligation of due diligence” under the duty to prevent significant harm to the environment

• RvR: §§295-298 seem to be about biodiversity

§299. Due diligence in preventing significant harm to the environment sometimes also implies an obligation of States to notify and consult in good faith with other States with respect to risks of adverse effects of their conduct. This obligation exists where planned activities within the jurisdiction or control of a State create a risk of significant harm, and notification and consultation is necessary to determine the appropriate measures to prevent that risk [...] notification and consultation are particularly warranted when an activity significantly affects collective efforts to address harm to the climate system, such as the implementation of policy changes in relation to the exploitation of resources linked to GHG emissions, or with respect to information that is necessary for meaningful co-operation among States to address the adverse effects resulting from GHG emissions.

• RvR: Dit zet Trump met zijn billen bloot (en dat is geen fraai gezicht)

§301. the duty of States to co-operate for the protection of the environment has a customary character

• RvR: Uitzoeken: Wat bewerkstelligt "customary" in de praktijk?
• RvR: VCLT 34 zegt wel dat een derde staat niet meegezogen kan worden...
• RvR: §§306,308 legt dit uit met "The duty to co-operate is founded on the recognition of the interdependence of States"

§305. States must co-operate to achieve concrete emission reduction targets or a methodology for determining contributions of individual States, including with respect to the fulfilment of any collective temperature goal.

§306. discretion in determining the means for regulating their GHG emissions [...] cannot serve as an excuse for States to refrain from co-operating with the required level of due diligence or to present their effort as an entirely voluntary contribution which cannot be subjected to scrutiny.

§308. Climate change is a common concern. Co-operation is not a matter of choice for States but a pressing need and a legal obligation.

Biodiversity

§326. Biodiversity is defined by the Biodiversity Convention as comprising “the variability among living organisms” and “the ecological complexes of which they are part”. This includes diversity of ecosystems (see paragraph 127 above). Ecosystems, in turn, are defined in Article 2 as including the “non-living environment” in so far as it interacts with life to form a functional unit.

§327. States parties to the [Biodiversity] Convention have the responsibility to ensure that activities within their jurisdiction or control do not cause damage to the environment of other States or of areas beyond the limits of national jurisdiction.

§328. each State party must, in accordance with its particular conditions and capabilities, “[d]evelop national strategies, plans or programmes for the conservation and sustainable use of biological diversity”

International Human Rights Law

§371. States have obligations under international human rights law to respect, protect and ensure the enjoyment of human rights of individuals and peoples. Human rights are focused on the protection of individuals and peoples and are not limited to specific fields of activity.

§373. the protection of the environment is a precondition for the enjoyment of human rights, whose promotion is one of the purposes of the United Nations as set out in Article 1, paragraph 3, of the Charter.

• RvR: §377, the inherent right to life of every human being
• RvR: §379, right of everyone to the enjoyment of the highest attainable standard of physical and mental health
• RvR: §380, close connection between the environment and the right to an adequate standard of living
• RvR: §381, right to privacy, family and home
• RvR: §382, rights of women, children and indigenous peoples
• RvR: Dit kan helpen met toepassing van Aarhus

§386. Based on all the above, the Court considers that the adverse effects of climate change may impair the effective enjoyment of human rights.

§392. The General Assembly “[r]ecognizes the right to a clean, healthy and sustainable environment as a human right”

§393. a clean, healthy and sustainable environment is a precondition for the enjoyment of many human rights

Attribution

§427. Failure of a State to take appropriate action to protect the climate system from GHG emissions — including through fossil fuel production, fossil fuel consumption, the granting of fossil fuel exploration licences or the provision of fossil fuel subsidies — may constitute an internationally wrongful act which is attributable to that State.

§428. In relation to private actors, the Court observes that the obligations it has identified under question (a) include the obligation of States to regulate the activities of private actors as a matter of due diligence. [...] Thus, a State may be responsible where, for example, it has failed to exercise due diligence by not taking the necessary regulatory and legislative measures to limit the quantity of emissions caused by private actors under its jurisdiction.

§429. the Court observes that while climate change is caused by cumulative GHG emissions, it is scientifically possible to determine each State’s total contribution to global emissions, taking into account both historical and current emissions. [...] It is important to recall at this stage that what constitutes a wrongful act is not the emissions in and of themselves but actions or omissions causing significant harm to the climate system in breach of a State’s international obligations.

§430. the rules on State responsibility under customary international law are capable of addressing a situation in which there exists a plurality of injured or responsible States.

§431. Therefore, in the climate change context, the Court considers that each injured State may separately invoke the responsibility of every State which has committed an internationally wrongful act resulting in damage to the climate system and other parts of the environment. And where several States are responsible for the same internationally wrongful act, the responsibility of each State may be invoked in relation to that act.

§432. Thus, the Court considers that the rules on State responsibility admit the possibility of determining the responsibility of States in the climate change context.

Causation

§433. For a finding of State responsibility, what is required is an internationally wrongful act and its attribution to a State, whether the act causes harm or not.

§436. The existing legal standard for establishing causation [...] requires the existence of “a sufficiently direct and certain causal nexus between the wrongful act . . . and the injury suffered by the Applicant” [...] is flexible enough to address the challenges arising in respect of the phenomenon of climate change.

§438. In light of the foregoing, the Court concludes that while the causal link between the wrongful actions or omissions of a State and the harm arising from climate change is more tenuous than in the case of local sources of pollution, this does not mean that the identification of a causal link is impossible in the climate change context; it merely means that the causal link must be established in each case through an in concreto assessment

§440. States’ obligations pertaining to the protection of the climate system and other parts of the environment from anthropogenic GHG emissions, in particular the obligation to prevent significant transboundary harm under customary international law, are obligations erga omnes [for all].

§442. [a]ny State other than an injured State is entitled to invoke the responsibility of another State ... if ... the obligation breached is owed to the international community as a whole

§443. While a non-injured State may pursue a claim against a State in breach of a collective obligation, it may not claim reparation for itself. Rather, it may only make a claim for cessation of the wrongful act and assurances and guarantees of non-repetition, as well as for the performance of the obligation of reparation in the interest of the injured State or of the beneficiaries of the obligation breached.

Legal Consequences

§444. every internationally wrongful act of a State entails the international responsibility of that State

§448. 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. Additionally, in appropriate circumstances, a responsible State could be required to offer appropriate assurances and guarantees of non-repetition

§449. to establish reparation, 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.

§450. reparation must “wipe out all the consequences of the illegal act and reestablish the situation which would, in all probability, have existed if that act had not been committed”

CONCLUSIONS

§457. For these reasons,

THE COURT,

1. Unanimously,

   Finds that it has jurisdiction to give the advisory opinion requested;

2. Unanimously,

   Decides to comply with the request for an advisory opinion;

3. As regards question (a) put by the General Assembly:

   A) Unanimously,

   Is of the opinion that the climate change treaties set forth binding obligations for States parties to ensure the protection of the climate system and other parts of the environment from anthropogenic greenhouse gas emissions. These obligations include the following:
   
    a) States parties to the United Nations Framework Convention on Climate Change have an obligation to adopt measures with a view to contributing to the mitigation of greenhouse gas emissions and adapting to climate change;
    b) States parties listed in Annex I to the United Nations Framework Convention on Climate Change have additional obligations to take the lead in combating climate change by limiting their greenhouse gas emissions and enhancing their greenhouse gas sinks and reservoirs;
    c) States parties to the United Nations Framework Convention on Climate Change have a duty to co-operate with each other in order to achieve the underlying objective of the Convention;
    d) States parties to the Kyoto Protocol must comply with applicable provisions of the Protocol;
    e) States parties to the Paris Agreement have an obligation to act with due diligence in taking measures in accordance with their common but differentiated responsibilities and respective capabilities capable of making an adequate contribution to achieving the temperature goal set out in the Agreement;
    f) States parties to the Paris Agreement have an obligation to prepare, communicate and maintain successive and progressive nationally determined contributions which, inter alia, when taken together, are capable of achieving the temperature goal of limiting global warming to 1.5°C above pre-industrial levels;
    g) States parties to the Paris Agreement have an obligation to pursue measures which are capable of achieving the objectives set out in their successive nationally determined contributions; and
    h) States parties to the Paris Agreement have obligations of adaptation and co-operation, including through technology and financial transfers, which must be performed in good faith;
   

   B) Unanimously,

   Is of the opinion that customary international law sets forth obligations for States to ensure the protection of the climate system and other parts of the environment from anthropogenic greenhouse gas emissions. These obligations include the following:
   
    a) States have a duty to prevent significant harm to the environment by acting with due diligence and to use all means at their disposal to prevent activities carried out within their jurisdiction or control from causing significant harm to the climate system and other parts of the environment, in accordance with their common but differentiated responsibilities and respective capabilities;
    b) States have a duty to co-operate with each other in good faith to prevent significant harm to the climate system and other parts of the environment, which requires sustained and continuous forms of co-operation by States when taking measures to prevent such harm;
   

   C) Unanimously,

   Is of the opinion that States parties to the Vienna Convention for the Protection of the Ozone Layer and to the Montreal Protocol on Substances that Deplete the Ozone Layer and its Kigali Amendment, the Convention on Biological Diversity and the United Nations Convention to Combat Desertification in Those Countries Experiencing Serious Drought and/or Desertification, Particularly in Africa, have obligations under these treaties to ensure the protection of the climate system and other parts of the environment from anthropogenic greenhouse gas emissions;
   

   D) Unanimously,

   Is of the opinion that States parties to the United Nations Convention on the Law of the Sea have an obligation to adopt measures to protect and preserve the marine environment, including from the adverse effects of climate change and to co-operate in good faith;
   

   E) Unanimously,

   Is of the opinion that States have obligations under international human rights law to respect and ensure the effective enjoyment of human rights by taking necessary measures to protect the climate system and other parts of the environment;
   

4. As regards question (b) put by the General Assembly:

   Unanimously,

   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.

Done in French and in English, the French text being authoritative, at the Peace Palace, The Hague, this twenty-third day of July, two thousand and twenty-five, in two copies, one of which will be placed in the archives of the Court and the other transmitted to the Secretary-General of the United Nations.