From courtrooms to policy: climate change and environmental disputes before international courts and tribunals
In the age of climate change and biodiversity loss, international courts and tribunals are increasingly called upon to address complex legal questions related to the protection of the environment and public health under international law. These forums have become pivotal in evaluating international state obligations relating to the impacts of climate change, including rising sea levels, wildlife degradation, access to water, and extreme weather events.
As discussions on environmental sustainability intensify at both global and national levels, governments and businesses are increasingly confronted with claims related to climate change and environmental issues. These cases involve issues of state responsibility, the role of private stakeholders, the enforcement of environmental standards, and the protection of affected communities. In this context, international courts and tribunals are not only arbiters of disputes but also influential actors shaping the trajectory of global environmental governance.
The increasing frequency of international environmental disputes marks a crucial turning point in the development of relevant legal norms, presenting both risks and opportunities for businesses. As discussed in this article, the period from 2025 to 2026 is poised to be a defining moment for such disputes. Among the most anticipated developments is the International Court of Justice's expected landmark advisory opinion on the scope of state obligations regarding climate change under international law. Once issued, this opinion is likely to set important precedents for future environmental litigation and arbitration.
As international courts and tribunals continue to engage with these important matters, the implications of their rulings extend beyond the immediate parties involved in each dispute. The outcomes of these cases are poised to influence not only the development of international law norms but also the decisions of domestic lawmakers, regulatory bodies, and national courts that adjudicate climate- and environment-related disputes, which highlights the integral role of international judicial bodies.
International proceedings on climate change and environmental issues
With an expanding body of cases, the following international dispute settlement forums are setting important precedents that could significantly influence domestic legal frameworks:
International Court of Justice (ICJ)
In March 2023, the UN General Assembly adopted Resolution A/RES/77/276, requesting the ICJ to provide an advisory opinion on the scope of state obligations concerning climate change. It posed two main questions: (i) what are international state obligations to protect the climate system from anthropogenic greenhouse gas emissions (GGEs), ensuring the well-being of both present and future generations; and (ii) what are the legal consequences for states that, through actions or omissions, cause significant climate harm, particularly concerning small island developing states and affected people? The UN’s request draws upon legal instruments such as the UN Charter, the International Covenant on Civil and Political Rights, and the Paris Agreement.
In December 2024, oral hearings commenced in The Hague, with participation from 96 countries and 11 international organisations. Small island nations have been at the forefront of the initiative. The US, China, and the EU also presented positions. The ICJ allowed submissions from experts to help form an understanding of the scientific basis and impacts of climate change.
Inter-American Court of Human Rights (IACtHR)
Similarly, the IACtHR has been deliberating on a landmark advisory opinion on climate change and state obligations under the American Convention on Human Rights. This followed a request made by Chile and Colombia in January 2023, highlighting considerations for region-specific human rights standards. The request sought guidance, among other things on the duty of states to mitigate and adapt to climate change, including measures to prevent and respond to environmental loss and damage, as well as the protection of vulnerable populations such as children, indigenous people, and environmental defenders.
In April and May 2024, the IACtHR held oral hearings in Barbados and Brazil, inviting submissions from governments, civil society organisations, and academic institutions. Over 600 participants were reportedly involved in the proceedings.
In July 2025, the IACtHR issued its long-anticipated Advisory Opinion No. 32. The court declared that a stable and healthy climate is part of the human right to a healthy environment. The opinion outlines states’ obligations to mitigate and adopt measures in response to climate change. The court also held that states must restore damaged ecosystems, regulate both public and private activities, and hold emitters accountable.
European Court of Human Rights (ECtHR)
In April 2024, the ECtHR issued a decision in Verein KlimaSeniorinnen v. Switzerland, marking a landmark case in which a European court ruled on the intersection of climate change and human rights. The applicants, a Swiss association of over 2,000 women, predominantly aged 70 and above, argued that their health and well-being were threatened by climate change and global warming, in breach of their rights to life and health under the European Convention on Human Rights. They argued that more deaths than usual occurred during hot summers, and that the defendant had missed its 2020 climate targets. Highlighting the global significance of the case, other governments, NGOs, and UN bodies participated in the proceedings.
The ECtHR held that the defendant had failed to fulfil its positive obligations to protect citizens from the adverse effects of climate change and had taken no timely or sufficient action to mitigate it, thereby endangering the applicants’ health and quality of life. It expressed the view that states have a duty to adopt and effectively implement measures to mitigate climate change, with a view to achieving net-zero GGEs within three decades.
International Tribunal on the Law of the Sea (ITLOS)
In May 2024, the ITLOS issued a significant advisory opinion affirming state obligations under the UN Convention on the Law of the Sea (UNCLOS) to protect the marine environment from climate change caused by GGEs. This followed a request from a coalition within the Commission of Small Island States on Climate Change, including countries such as Antigua and Barbuda, which sought clarification on UNCLOS obligations regarding the prevention, reduction, and control of marine pollution resulting from the impact of climate change, such as ocean warming, rising sea levels, and ocean acidification.
Investment treaty tribunals
Finally, arbitral tribunals adjudicating investor-state disputes under international investment treaties play a crucial role. In recent years, political, legal, and social debates regarding the environmental impact of certain economic activities have steadily increased. This has led to a growing number of investor-state arbitrations related to the environment. By the end of 2021, the UN noted that approximately 15% of all known treaty-based investment arbitrations had been initiated in relation to circumstances involving an environmental component.
Examples include cases such as Perenco v. Ecuador, an investment arbitration concerning the environmental impacts of oil extraction in the Amazon rainforest. In this case, the tribunal ruled that the state has discretion under international law to adjust environmental laws in response to evolving perspectives and the risks posed by certain activities. In Eco Oro v. Colombia, the tribunal found that the delimitation of a mining project in a mountain ecosystem – home to native flora and fauna vital for maintaining biodiversity – qualified as a legitimate exercise of the state’s power to protect the environment. As with proceedings before international courts, the “precautionary principle” often plays a role in such investment arbitrations. The underlying concept is that states must prioritise proactive planning to prevent environmental damage. Scientific uncertainty regarding the causality, probability, and nature of such damage is considered to justify the right to take action.
Potential implications: what’s next?
The decisions of these international courts and tribunals are likely to carry significant political and legal weight at both the international and domestic levels, with implications for governments and businesses alike.
The ICJ’s advisory opinion is expected later in July this year. While such opinions are non-binding, it could establish a foundational understanding of state responsibilities regarding climate change that may influence international and national governance, and prompt countries to adjust their environmental policies. The opinion may also guide litigation and arbitration between states and companies, where established principles may be used as arguments, and between companies and individuals, where legal actions might be based on the opinion’s findings. Both international tribunals and domestic adjudicators are likely to take the ICJ opinion into account.
Given their previous influential decisions, the IACtHR’s and ECtHR’s findings are expected to provide authoritative guidance on the human rights dimensions of climate change. The IACtHR's Advisory Opinion is anticipated to influence policies and legal frameworks across the Americas. Similarly, the ECtHR’s decision affirms that human rights offer a framework for addressing climate change. This ruling could serve as a guiding principle for the 45 other member states of the Council of Europe.
The ITLOS advisory opinion provides an interpretation of state accountability for maritime pollution resulting from climate change. As such, it is likely to set a precedent for future environmental laws and the use of UNCLOS as a tool for marine protection.
Finally, it will be interesting to see how awards in investor-state arbitrations related to the environment may inform future legal actions and policy decisions by states where foreign investments are made. These cases have become an important framework for environmental considerations in international arbitration. This development is expected to evolve with the conclusion of new international investment treaties worldwide.
Conclusion
Climate-related and environmental decisions by international courts and tribunals are expected to carry legal and political implications at the global and national levels. Businesses will need to closely monitor these developments since they may be directly impacted by regulatory changes and the growing emphasis on environmental responsibility. This includes sustainability practices, climate-conscious policies, and investments in response to emerging international standards. Businesses could seize opportunities by aligning their operations with evolving environmental practices, fostering innovation in new technologies, or engaging in proactive partnerships aimed at addressing concerns. Ultimately, the continued evolution of legal frameworks around climate and environmental issues will not only shape global governance but also create opportunities for businesses worldwide.
