Climate Change and Legal Remedies: IACtHR Advisory Opinion 31/25 on Access to Justice in Climate Disputes

On 3 July 2025, the Inter American of Human Rights (IACtHR or Court) issued its long-anticipated Advisory Opinion 31/25 (Opinion) on climate change and state obligations under the American Convention on Human Rights (ACHR). The IACtHR's findings were groundbreaking. The Court ruled that the duty of states not to cause irreversible damage to the climate and environment must be regarded as a jus cogens norm – a peremptory norm of international law that no state or international agreement may violate or derogate from. 

The Opinion is expected to influence policies and legal frameworks across the Americas, and further shape the development of international legal norms on climate change and environmental protection. This article provides an overview of the IACtHR's findings on one particular aspect: climate harm, legal remedies, and access to justice in climate-related disputes.  

Background of the Advisory Opinion

The IACtHR's Opinion followed a joint request made by Chile and Colombia in January 2023, seeking guidance on human rights duties of states to mitigate and adapt to climate change. 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 involved in the proceedings.

In its 200-page comprehensive Opinion, the IACtHR interpreted the regional human rights obligations of ACHR states in light of what it described as a "climate emergency". 

The IACtHR's rulings include that a stable and healthy climate forms part of the human rights to life and health. Particularly notable is the Court's recognition of nature as a subject of rights that states are obligated to protect and restore. The Opinion also outlines various state obligations toward particularly vulnerable groups in the context of climate change, including children, indigenous peoples, and people in poor regions, as well as duties to protect the rights of environmental defenders from repression, violence, or arbitrary detention. The IACtHR also expressed the view that human rights obligations require states to mitigate greenhouse gas emissions and to set ambitious and timely mitigation targets. Furthermore, the Opinion addresses states' duties to prevent irreversible harm to the climate, exercise due diligence in identifying climate risks, adopt and maintain up-to-date domestic legal frameworks that address both private and public stakeholders, engage in international climate cooperation, and ensure access to accurate information and meaningful public participation.  Finally, the IACtHR emphasised the importance of companies in the climate context and requires states to adopt measures to prevent the potential human rights impact caused by private activities.

The IACtHR's Opinion forms part of a series of climate- and environment-related cases before international courts and tribunals. For example, the ruling refers to the 2024 decision of the European Court of Human Rights in Verein KlimaSeniorinnen as another international case addressing the intersection of climate change and regional human rights. The Opinion also cites the 2024 Advisory Opinion of the International Tribunal on the Law of the Sea, which affirmed the obligations of states under the UN Convention on the Law of the Sea to protect the marine environment from climate change caused by greenhouse gas emissions.

IACtHR's Ruling on Climate Disputes and Access to Justice 

From a dispute resolution perspective, the IACtHR explicitly addresses the handling of climate-related cases in its recent Opinion. The Court emphasises that the ACHR obligates states to provide effective judicial remedies for victims of human rights violations (Article 25), in line with the guarantees of due process (Article 8.1). The IACtHR underscores that fulfilling these obligations is particularly crucial in the context of climate change.

According to the IACtHR, to fulfill these obligations, states must address the following points:

Provision of sufficient Resources for the Administration of Justice in Climate Disputes

First, the IACtHR emphasises that, given the unique challenges posed by climate-related litigation, states must adopt comprehensive procedural and substantive measures to ensure effective access to justice. This includes continuous training for judicial actors on climate change and its human rights impact, adopting an interdisciplinary and intercultural approach, and ensuring decisions are based on the best available science. The Court further calls on states to allocate adequate resources to relevant institutions, consider the creation of specialised environmental and climate bodies, and guarantee equal access to justice for vulnerable populations. This includes offering free legal proceedings to those unable to bear the costs of climate-related litigation.

Application of the "Pro Actione" Principle 

Second, the IACtHR highlights the importance of the pro actione principle in climate disputes, especially given the disproportionate effects on vulnerable populations. This principle states that procedural rules must be interpreted in the way most favourable to access justice, ensuring that formal barriers do not prevent individuals from having their climate-related claims heard and resolved.

Guarantee of a reasonable Timeframe for Proceedings

Third, the Court held that timely access to justice, as required under Articles 25 and 8.1 of the ACHR, must include a guarantee that proceedings are conducted and judgments executed within a reasonable timeframe. In climate-related cases, courts must not only consider traditional factors like case complexity and judicial conduct, but also the urgency of climate risks, the human rights impact of delays and the vulnerability of affected individuals.

Adequate Provisions on Legal Standing

Fourth, the Opinion affirms that legal standing requirements must not become barriers to the access of justice in climate disputes. In the IACtHR's view, applying the pro actione principle, courts must interpret standing rules in a manner that facilitates both individual and collective claims. 
For collective claims, the Court highlights the need for broad legal standing. Civil society and state institutions must be given real opportunities to bring claims, supported by adequate technical, financial, and human resources. States should develop legal frameworks that allow collective legal action without requiring proof of personal harm. For individual claims, the Opinion emphasises that states must provide effective remedies to restore the rights of those harmed by climate change. While states may maintain requirements for direct or personal standing, they should also ensure flexible approaches that consider climate-related vulnerabilities. Courts should assess standing in light of the individual or group's exposure to climate risks, geographic location, adaptive capacity, and existing social or economic inequalities that may increase their susceptibility to harm. This inclusive interpretation helps to ensure that those most affected by climate change are not excluded from accessing justice.

Furthermore, the IACtHR underscores the transboundary nature of climate harm and reaffirms that states are responsible for preventing and remedying such harm when it originates from activities within their territory or jurisdiction. This includes a duty to repair damage caused to individuals or other states, provided there is a demonstrable causal link. Accordingly, access to justice must also be extended to individuals and entities located outside the state's territory, reinforcing the principle that climate justice transcends national borders.

Appropriate Rules regarding the Burden and Admissibility of Evidence

Fifth, the IACtHR notes that the complexity of climate disputes often makes the strict application of traditional evidentiary rules a barrier to justice. Challenges such as proving causal links between harm and its origin, unequal access to evidence (including satellite data), and the concentration of technical information among powerful actors require a more flexible and context-sensitive approach. Judicial authorities must interpret evidentiary rules in light of key principles, such as pro personae, pro natura, pro actione, and procedural cooperation, to accommodate the specific characteristics of climate-related cases.

To ensure effective access to justice, the Opinion emphasises the need for alternative evidentiary standards that rely on the best available science. This includes allowing presumptions on the link between greenhouse gas emissions, climate degradation, and the resulting risks to people and ecosystems. Courts should also consider reversing the burden of proof and addressing asymmetries between parties, especially where vulnerable communities are involved. Moreover, access to evidence – particularly satellite data – must be guaranteed, and international cooperation in technology transfer should be promoted to support the use of such evidence in climate litigation.

Availability of effective Reparations

Finally, the IACtHR recognises a broad spectrum of reparations necessary to address climate harm. Beyond monetary compensation, effective reparations include restitution, rehabilitation, satisfaction, and guarantees of non-repetition. States are obligated to provide accessible judicial and administrative mechanisms that deliver comprehensive reparations tailored to the nature of climate harm, considering its specific impacts on individuals and ecosystems. Reparative measures should also enhance the adaptive capacity and resilience of affected communities and natural systems to support sustainable recovery.

In practice, reparations may include restoring the climate system and ecosystems through enhanced mitigation efforts and conservation plans, providing timely and culturally appropriate health care for climate-related health issues, and offering compensation based on scientifically sound assessments of loss. Additionally, guarantees of non-repetition should focus on reducing vulnerability, monitoring compliance with obligations, and strengthening resilience within sustainable development frameworks. All reparative actions must rely on the best available science and respect the substantive and procedural rights of those affected. The Court further urges states and relevant authorities to avoid limiting reparations to financial compensation alone and to consider establishing mechanisms to monitor the implementation of reparative measures where necessary.

Conclusion

While advisory opinions of international courts and tribunals are non-binding, they often establish foundational understandings of state responsibilities under relevant international law. This is expected to be the case with the IACtHR’s recent Opinion, which is poised to influence the international environmental law framework as well as decisions by other international courts and tribunals. In particular, the IACtHR’s rulings on access to justice in climate disputes could also impact domestic lawmakers and national courts.

For more information on the IACtHR's Advisory Opinion 31/25, contact your CMS client partner or this CMS expert.