The ICJ just ruled countries can be held liable for climate change damage
7 August 2025
In case you missed it, on Wednesday 23 July 2025 the International Court of Justice - the world’s highest court - delivered a landmark advisory opinion declaring that all countries have a legal obligation to protect and prevent harm to the climate.
The court, created as part of the United Nations in 1945, affirmed that countries must uphold existing international laws related to climate change and, if they fail to act, could be held responsible for damage to communities and the environment.
The opinion largely rests on the application of existing international law and clarifies that climate “harms” can be clearly linked to major emitters and fossil-fuel producers.
The case, which was triggered by a group of Pacific island students and championed by the government of Vanuatu, saw unprecedented levels of input from nations.
The opinion also says that limiting global warming to 1.5°C should be considered the “primary temperature goal” for nations and, to achieve it, they are obliged to make “adequate contributions”.
The unanimous decision further concludes that the production and consumption of fossil fuels “may constitute an internationally wrongful act attributable to that state”.
Key findings
[Lynsi Burton, Stockholm Environment Institute, 28 Jul 2025]
Climate change treaties and other multilateral environmental agreements contain binding obligations for states in relation to protecting the climate system from greenhouse gas emissions.
Customary international law also contains state obligations in relation to protecting the climate system, including (a) the duty to prevent significant harm to the environment by acting with due diligence and in accordance with common but differentiated responsibilities and respective capabilities; and (b) the duty to cooperate in good faith to prevent significant harm.
Climate change impacts human rights, and states have an obligation to respect and ensure their effective enjoyment by protecting the environment and climate system.
With regard to breaches of these obligations, the Court found that such violations constitute “an internationally wrongful act”, and that legal consequences may arise as a result. These consequences could include reparations, guarantees of non-repetition, and cessation of the wrongful act or acts.
The President of the Court, HE Judge Iwasawa Yuji. Wednesday 23 July 2025
Photograph: UN Photo/ICJ-CIJ/Frank van Beek.
Climate change is “an existential problem of planetary proportions that imperils all forms of life and the very health of our planet”.
Legal experts and activists alike are hailing the decision as a turning point in climate accountability. For a succinct overview we recommend this Carbon Brief.
The UN Secretary-General António Guterres issued a video welcoming the opinion, stating:
"This is a victory for our planet, for climate justice and for the power of young people to make a difference."
Local academics, Professor Regina Scheyvens and Professor Glenn Banks at Massey University, were similarly excited stating:
“There can be – indeed we can now predict that there will be - real costs associated with our non-compliance with the agreements that we sign up to.”
Here at EIL we are resolutely ignoring the statement that “International law . . . has an important but ultimately limited role in resolving this problem”. Because the devil is in the detail and the Summary Opinion has some excellent detail worth reading (read on).
ICJ Summary Opinion Best Bits
…”the consequences of climate change are severe and far-reaching; they affect both natural ecosystems and human populations. Rising temperatures are causing the melting of ice sheets and glaciers, leading to sea level rise and threatening coastal communities with unprecedented flooding. Extreme weather events, such as hurricanes, droughts and heatwaves, are becoming more frequent and intense, devastating agriculture, displacing populations and exacerbating water shortages. Furthermore, the disruption of natural habitats is pushing certain species toward extinction and leading to irreversible loss of biodiversity. Human life and health are also at risk, with an increased incidence of heat-related illnesses and the spread of climate-related diseases. These consequences underscore the urgent and existential threat posed by climate change.”
“ The duty to prevent significant harm to the environment is an obligation to act with due diligence… , the Court recognizes that the standard of due diligence for preventing significant harm to the climate system is stringent. Moreover, due diligence entails not only the adoption of appropriate rules and measures, but also a certain level of vigilance in their enforcement and the exercise of administrative control. As concerns climate change, a heightened degree of vigilance and prevention is required.”
[The Court]
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.
…
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;
…
E. 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.
Small island states like Vanuatu, Tuvalu, Barbados and others across the Pacific and Caribbean are among the most vulnerable to climate change, yet they have contributed little to global emissions.
Who is the ICJ anyway?
[Misha Ketchell, The Conversation, 2 August, 2025]
The International Court of Justice, commonly referred to as the ICJ or World Court, can help settle disputes between states when requested, or it can issue advisory opinions on legal questions referred to it by authorized U.N. bodies such as the General Assembly or Security Council. The advisory opinion process allows its 15 judges to weigh in on abstract legal issues – such as nuclear weapons or the Israeli occupation of the Palestinian territories – without a formal dispute between states.
While the court’s advisory opinions are nonbinding, they can still have a powerful impact, both legally and politically.
The rulings are considered authoritative statements regarding questions of international law. They often clarify or otherwise confirm existing legal obligations that are binding.