The Inter-American Court of Human Rights has just handed climate litigators in Latin America the most powerful tool they have ever had. Advisory Opinion OC-32/25, issued in 2025, does not merely interpret existing rights in the context of the climate crisis. It restructures the procedural architecture of climate litigation by inverting burdens of proof, authorising the presumption of causal links between state emissions and climate harm, and recognising satellite imagery as evidence that states must make accessible to victims. For organisations that have spent years fighting for communities on the front lines of the climate emergency, this is not an incremental development. It is a transformative moment.

The Opinion did not emerge from a vacuum. Over the past decade, the Inter-American Court has built the foundations step by step. In 2017, Advisory Opinion OC-23 established the right to a healthy environment as an autonomous right under the American Convention – not a derivative entitlement, but a freestanding legal guarantee with its own independent status. That standard moved from theory to practice in the contentious case of La Oroya v. Peru, where the Court found that severe environmental contamination created a systemic risk to life, health, and physical integrity. OC-32/25 is the third step in this trajectory – and by far the most ambitious.

The Opinion characterises the climate crisis as a human rights problem that falls disproportionately on those already marginalised. It maps the vulnerabilities of Latin America and the Caribbean with precision, identifying Central America, the Amazon, the Caribbean and the Andes as zones of existential risk. The figures the Court cites are sobering. In 2021, the region counted 17.1 million internally displaced persons due to climate-related causes. The top one per cent of the population generated 92 per cent of per-capita CO₂ emissions in 2019, while the bottom 50 per cent generated just 0.27 per cent. Those who emit the least suffer the most.  Across these ecosystems, indigenous peoples and traditional communities are disproportionately affected by ongoing violations of their rights linked to climate change.

A New Autonomous Right

From the right to a healthy environment, the Court derives a new autonomous right: the right to a healthy climate, defined as the right to live in a climate system free from dangerous anthropogenic interference. The Opinion treats this right as an indispensable precondition for the exercise of all other human rights in the context of the climate emergency. States are accordingly bound by a standard of heightened due diligence. Climate governance is no longer treated as a matter of political discretion alone. States must prevent climate harm inside and beyond their borders, require environmental impact assessments to include specific analyses of greenhouse gas emissions before authorising projects, and set ambitious, progressive reduction targets calibrated to the best available science. The scientific consensus reflected in IPCC assessments is explicitly treated as the legal reference standard.

The Court adds a prohibition on regression: protection levels already achieved are a floor, not a ceiling. It extends due diligence obligations not only to states’ own activities but also to companies operating under their jurisdiction. These propositions are not entirely new, but the Opinion consolidates them into a unified framework and gives them the authority of a definitive Inter-American interpretation. For litigation purposes, the catalogue of obligations is now largely settled.

Procedural Rights as the Real Innovation

If the substantive obligations are important, the procedural innovations are transformative. The most significant contribution of OC-32/25 for climate litigation is not the declaration of a right to a healthy climate – it is the way the Opinion restructures the access rights framework. Indeed, the Court developed two very valuable elements: the right to science, and standards of proof and evidence that strengthen climate litigation.

“The right to science includes access to the benefits of scientific and technological progress and to the co-production of knowledge between scientists and holders of local, traditional and indigenous knowledge.” (par. 473)

The right to science, grounded in Article 13 of the International Covenant on Economic, Social and Cultural Rights and read together with OC-32/25, creates enforceable obligations for states to guarantee effective access to scientific climate knowledge. States can no longer rely on claims of scientific uncertainty or insufficient knowledge: policies must be based on the best available science and updated as that science evolves. Environmental impact assessments (par. 362), national adaptation plans (par. 388), and Nationally Determined Contributions are treated as auditable documents that must rely on scientifically credible evidence and remain transparent (parr. 510, 511 and 486). Most significantly, judges can and must evaluate whether the scientific basis relied upon by the state satisfies Convention standards (parr. 488–539). This substantially expands the scope of judicial review of climate policy within the Inter-American system.

Reversing the Burden of Proof

Proving a direct causal link between a specific state’s emissions and a specific harm has historically been the single greatest obstacle in climate litigation – technically demanding, judicially contested, and practically out of reach for most affected communities. OC-32/25 dismantles that obstacle in four concrete moves.

The Opinion acknowledges that climate litigation is characterised by marked asymmetries between parties in their access to technical and scientific information. National courts must therefore adopt measures – including the reversal of the burden of proof – to guarantee effective judicial protection. The language is direct: “the burden of justifying any denial always falls on the State” (par. 490). In matters of information access passivity is not an option for the state.

Second, the Opinion accepts a presumption of the causal nexus between a state’s greenhouse gas emissions and the degradation of the global climate system, and in turn the link between that degradation and the risks facing people and ecosystems – provided this is anchored in IPCC assessments. This responds directly to the attribution problem that has shaped the limits of climate litigation for decades. Courts are no longer required to resolve the full scientific chain of causation in each individual case.

Third, the Opinion introduces alternative standards of proof. Access to climate justice does not require proving individualised causation for each harm. It is sufficient to demonstrate the generation or tolerance of significant risks through state inaction, and the effective exposure of people or groups to those risks. Communities do not need to show that a specific tonne of CO₂ from a specific state caused their specific flood. They need to show that they were exposed to foreseeable risks that the state failed to address.

Fourth, the Court highlights satellite evidence as particularly relevant in climate cases and requires states to ensure cooperation and technology transfer to make such evidence accessible to victims in judicial proceedings. This is a practical recognition that the evidentiary tools needed for climate litigation are often technically sophisticated and economically inaccessible to the communities that need them most.

What Changes for Litigation

Taken together, these four innovations transform the strategic landscape for climate litigation across the Americas. Organisations like AIDA can now challenge fossil fuel projects whose environmental impact assessments fail to incorporate adequate climate analysis – invoking the right to science directly. We can contest state climate policies on the grounds of scientific insufficiency or obsolescence. We can bring cases on behalf of entire communities without proving individual, direct harm, thanks to the broad standing the Opinion recognises. And we can defend indigenous territories by connecting climate damage to collective territorial rights through a framework that no longer demands the near-impossible standard of individualised causation.

OC-32/25 is not a self-executing judgment. Its standards will need to be invoked, argued, and developed case by case before the Inter-American Court, the Commission, and national courts across member states. Resistance from states that seek to preserve the status quo is predictable. But the architecture is now in place: the applicable rules have changed.

At AIDA, we have spent years litigating in a region where the gap between states’ formal climate commitments and the actual protection experienced by communities is vast. OC-32/25 gives us legal instruments to narrow that gap. It does not ask us to be more optimistic. It asks us to be more ambitious – in the cases we choose, in the standards we invoke, and in the connections we draw between international law and the communities on the front lines of the climate crisis.