As the harmful impacts of climate change manifest rapidly, there is a growing need for judicial and similar remedies to address states’ responsibilities for greenhouse-gas emissions, failures in mitigation or adaptation, and related human-rights claims. Furthermore, the number of cases involving private companies’ liability is increasing, particularly in relation to misleading ‘green’ claims. At the same time, a parallel trend can be observed: stringent climate regulations are being contested. Overall, we are witnessing an evolving area of litigation—not only at the national level but also at the regional and international levels—where legal mechanisms are used to address the legal dimensions of climate change.
The Rise of Climate Litigation
The United Nations Environment Programme began assessing trends in climate litigation in 2017. The first report documented 884 cases in 24 countries. The 2020 report showed an emerging trend: the number of cases reached 1,550 in 38 countries. This tendency persisted in 2023, with a report recording 2,180 cases across 65 jurisdictions. The latest report registered 3,099 cases in 55 countries, as well as proceedings before 24 international courts or similar bodies, between 2023 and the first half of 2025.
These reports define climate cases broadly, including ‘classical’ national court proceedings, private international law claims, complaint mechanisms before international judicial bodies, and requests for advisory opinions. Notably, the International Tribunal for the Law of the Sea (ITLOS), the Inter-American Court of Human Rights, and the International Court of Justice have all delivered advisory opinions emphasizing state responsibility in the climate context and elaborating on what that responsibility entails.
State Responsibility in the Climate Crisis: Mitigation, Adaptation, GHG Emissions, and Human Rights
State responsibility was first acknowledged in 2007 in Massachusetts v EPA, in which the US Supreme Court faulted the federal government’s Environmental Protection Agency for refusing to regulate emissions of polluting gases. Then, in 2020, the Dutch Supreme Court held the government responsible, in the Urgenda case, for failing to adopt adequate measures to curb greenhouse-gas emissions (GHG). The court emphasized that the state was obligated to take appropriate steps to mitigate the adverse effects of climate change.
Other cases focus on the states’ obligations under the Paris Agreement. For instance, in the case of PSB et al v Brazil, the Brazilian Supreme Federal Court ruled that a national act that contradicts the Paris Agreement may be declared invalid. At the same time, any emission or action violating this agreement can also be considered a human rights violation. In 2024 the Mexican Supreme Court upheld as constitutional a law allowing the limitation of domestic water supply to 50 litres per day after two consecutive missed payments. However, the court also declared that access to a clean and continuous water supply is a climate issue, and that the limitation should not be applied uniformly, as it could undermine resilience. Therefore, the 50-litre limit should be applied more flexibly in cases where people are affected by high temperatures due to climate change.
Beyond domestic cases, avenues for climate litigation at regional international courts have also begun to emerge. In Verein KlimaSeniorinnen v Switzerland, the European Court of Human Rights (ECtHR) delivered its first ‘climate judgement’. Its earlier environmental case law was largely based on a clear connection between the environmental harm and the applicants’ homes, which was not well-suited to the more diffuse nature of climate change. In the foregoing case, a group of elderly women, together with the nongovernmental organization (NGO) representing their interests, filed a complaint alleging that the state had failed to limit GHG emissions and to protect them from the adverse effects of climate change, in violation of their rights to life and to private and family life.
‘The court accepted the NGO’s standing but not that of the individual applicants, despite evidence showing that elderly people are more vulnerable to climate impacts’
The court accepted the NGO’s standing but not that of the individual applicants, despite evidence showing that elderly people are more vulnerable to climate impacts. The court also found that it had not been shown that the applicants required special individual protection. The ECtHR emphasized that states should pay particular attention to the adverse effects of climate change when weighing competing public and personal interests and should take all appropriate measures to mitigate those effects—especially for vulnerable citizens and with due regard for the interests of future generations. By contrast, a year later, in Greenpeace Nordic v Norway, the court found that the Norwegian government had not violated human rights by issuing oil and gas exploration permits. However, the ECtHR also emphasized that states are obligated to conduct thorough, timely, and comprehensive environmental impact assessments—based on the best available scientific knowledge—before permitting potentially hazardous activities.
Corporate Accountability in Climate Litigation: Emissions, Greenwashing, and Adaptation Failure
Another growing field of climate litigation targets private companies for various reasons. These cases, however, have certain limitations. For instance, in 2022, several Puerto Rican municipalities filed a complaint against energy companies—including Exxon, Shell, BP, and Chevron—alleging that they misled the public about the climate impact of their activities and hindered the development of clean-energy technologies. The court declined to examine the complaint on the merits and rejected it on procedural grounds, holding that it had been filed outside the four-year deadline for antitrust plaintiffs. Beyond procedural hurdles, Milieudefensie v Royal Dutch Shell illustrates that judicially determining the exact extent of required emissions reduction remains challenging.
In 2021 the Hague District Court required Shell to cut its direct and indirect emissions by 45 per cent by 2030, relative to 2019 levels. Shell challenged the decision, and the court of appeal upheld a general duty to reduce GHG emissions but set aside the specific 45 per cent target, reasoning that there is no scientific or legal consensus on the precise level of reduction. In 2025 Milieudefensie appealed to the Supreme Court, and the case remains pending.
Cases based on greenwashing allegations appear to be more successful, possibly because of their link to consumer-protection and competition law. In 2022 the Dutch advertising regulatory commission ruled against KLM Airlines, finding that its ‘Fly Responsibly’ campaign misleadingly claimed that using its flights is climate-neutral because the company compensates for all emissions—an assertion that could not be sufficiently substantiated. In 2024 the United Kingdom’s advertising regulatory authority fined BMW and MG Motor for claims that their electric cars have ‘no emissions’, which can mislead consumers about product-related and other indirect emissions.
Looking Ahead: Opportunities and Challenges
Procedural difficulties, short deadlines, challenges in proving personal standing, and applicants’ limited expertise or resources can still constitute barriers to climate-related legal action. However, the growing number of climate cases demonstrates an increasing demand for these judicial remedies. Several courts around the world have delivered potentially precedent-setting judgments, such as the ECtHR in KlimaSeniorinnen. Ambition, however, has not been linear; the outcomes in Milieudefensie have been more restrained.
The latest UNEP report also highlights ‘backlash’ cases, in which claims are directed against stringent climate regulations. In ANVR, TUI, and Prijsvrij v The Hague, companies unsuccessfully contested a regulation banning advertisements for goods and services linked to fossil-fuel use in private and public spaces. At the international level, Russia requested consultations at the WTO in May under the dispute-settlement mechanism, claiming that the EU’s Carbon Border Adjustment Mechanism (CBAM)—which aims to tackle carbon leakage outside the EU—violates the rules of free international trade.
As a complex and rapidly evolving area of law, climate litigation is influencing proceedings globally and regionally, creating new avenues for national law enforcement and increasingly targeting states and corporations alike.
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