Unlocking Climate Accountability: How Advisory Opinions Advance Environmental and Ocean Justice
- Ocean Vision Legal Team
- Jul 25
- 8 min read
Key words: Advisory Opinion, Climate Change, Ocean Litigation
Litigatious actions to enforce States’ obligations to protect the environment, including climate change litigation, is growing around the world, like a global wave of action igniting change. In an unprecedented moment for international environmental law, three landmark Advisory Opinions on climate change obligations were initiated simultaneously before the world’s top international courts: the International Court of Justice (ICJ), the International Tribunal for the Law of the Sea (ITLOS), and the Inter-American Court of Human Rights (IACtHR).
While focusing on different perspectives, each request asks: What legal duties do States have to prevent and address climate harm? These proceedings mark a turning point in the global response to climate change, offering not only moral weight but also legal clarity to hold polluters accountable and to support those most impacted by ecological harm.
What Are Advisory Opinions?
Advisory Opinions are interpretations of international law by international courts or tribunals in response to a legal question that was posed to it by States or intergovernmental bodies (such as the UN General Assembly or regional human rights commissions). Unlike contentious cases, which produce legally binding judgements between States and can impact State relationships, Advisory Opinions are non-binding and therefore less controversial than contentious cases.
If Advisory Opinions are nonbinding, how are they useful?
Advisory Opinions have significant authoritative effect and broad application: They clarify the scope and content of international law and can shift norms, influence behavior, and catalyse future litigation.
Advisory Opinions are interpretations of the law by the highest regional and international courts - they thus clarify the concrete measures States must adopt to meet their international obligation with regard to the question posed to the court. This legal clarification enhances accountability, reinforces the international rule of law where ambiguity has prevailed, and turns abstract treaty principles into enforceable duties.
In doing so, Advisory Opinions develop a robust legal framework, which (with an according States’ practice) can even develop into customary international law that is binding even for States not party to specific treaties. This clarified legal framework may also inform the design and content of new legal instruments and guide implementation of existing treaties.
A successful Advisory Opinion will affirm that State’s failure to act in the face of their international obligations is not just a moral failing but constitutes a breach of international law: Once a top international court gives its legal interpretation rules on an issue, it paves the way for future contentious cases and increases the reputational cost of non-compliance. It offers legal leverage for States seeking to hold destructive practices to account and to prevent harm that might be unduly affecting them.
By defining what is lawful, Advisory Opinions reshape the legal landscape. They can centre issues which elevate the voices of those most vulnerable to Ocean and environmental degradation, including Indigenous, coastal, and Ocean-dependent communities.
Advisory Opinions are not only about securing a legal answer. They unlock the full potential of international law and existing obligations as a tool for action. They affirm that States committed to upholding Ocean protection and limiting global warming can lead by principle, regardless of size or political weight, and that non compliance with international obligations cannot persist under legal ambiguity.
As international courts in their findings heavily rely on the best available science, the Advisory Opinions can help transform scientific consensus into binding standards and mark a turning point in how the global community governs and protects planet Earth.
Therefore, though nonbinding, Advisory Opinions can be among the most effective legal tools to protect the marine environment and catalyse a future in harmony with Nature. OVL is determined to ensure that these powerful legal tools at our disposal are put to use.
Climate Change Advisory Opinions and their findings?
So what was the content of the three Advisory Opinions that were submitted by various Small Island Developing States (or, rather, Large-Ocean States) regarding State’s climate change obligations?
International Tribunal for the Law of the Sea - Advisory Opinion
The ITLOS Advisory Opinion was initiated by the Commission of Small Island States on Climate Change and International Law (COSIS) and delivered as the first of the three Advisory Opinions in May 2024. The ITLOS:
Clarified that anthropogenic greenhouse gas (GHG) emissions constitute marine pollution under Art. 1 (1) (4) UNCLOS, due to their harmful effects on the Ocean (warming, acidification, biodiversity loss).
Confirmed States are therefore obligated to act with due diligence and must take “all necessary measures” under Art. 194 (1) UNCLOS, to prevent, reduce, and control marine pollution caused by GHG emissions. Furthermore, under Art. 194 (2) UNCLOS, States must ensure GHG pollution under their control does not cause damage to other States or spread beyond areas where they exercise sovereignty, emphasizing transboundary responsibility; and
Confirmed that the obligation to prevent, reduce and control GHG emissions must be fulfilled in accordance with the best available science, the precautionary principle and environmental impact assessments, and includes the restoration of affected ecosystems.
It affirmed that the temperature and time goals of the Paris Agreement were based on the best available science and supported by a large number of States. These goals therefore inform the obligations of States under UNCLOS and must be met.
Inter-American Court of Human Rights - Advisory Opinion
On July 3rd, 2025, the Inter-American Court of Human Rights (IACtHR) delivered its Advisory Opinion on the interpretation of State obligations under Human Rights law in light of climate change. The IACtHR:
Explicitly recognised the Right to a Healthy Climate as a derivative of the Right to a Healthy Environment. The Right to a Healthy Environment is a fundamental right for the existence of humanity, and the obligations derived from this right are intended to protect the global climate system for the benefit of humanity as a whole, of which both present and future generations are a part.
Confirmed States have the obligation to respect and guarantee Human Rights in light of the climate emergency. This includes the obligation to refrain from any behavior that may generate more harm, to adopt all necessary measures to reduce the risks derived from the degradation of the global climate system, and the obligation to cooperate in good faith to advance the respect for Human Rights.
Confirmed States must prevent irreversible environmental harm. This is a jus cogens obligation (a peremptory norm of international law) and applies regardless of borders; transboundary damage creates international legal responsibility.
Affirmed that ecosystems and Nature can be legal subjects, whose ecological integrity and functions must be protected. It recognises that the recognition of Nature and its components as subjects of rights provides a favorable framework for States and actors to advance sustainable development (Rights of Nature); and
Emphasised States have a positive obligation to adopt measures to ensure the protection, restoration and regenerations of ecosystems and that these measures must recognise the value of traditional, local and Indigenous knowledge.
International Court of Justice (ICJ) - Advisory Opinion
The Advisory Opinion to the International Court of Justice (ICJ) requested by Vanuatu was adopted by a UN General Assembly resolution in March 2023 and was delivered on 23 July 2025. Specifically, the Court:
Rejected the lex specialis argument pushed by major polluting countries that only climate-specific agreements like the UNFCCC, Kyoto Protocol, and the Paris Agreement apply. It confirmed that all countries have binding obligations to cut emissions under a range of international law, including human rights law, the Law of the Sea, customary international law, and other relevant treaties.
Like ITLOS, the ICJ confirmed that the 1.5°C limit isn’t just a political goal, but a legally binding target under the Paris Agreement and international law.
Affirmed liability for climate harm, finding that States failing to meet their legal obligations could be held responsible for climate-related harms and required to provide restitution, compensation, or satisfaction. This could include building infrastructure or restoring ecosystems.
Declared that States may breach international law by failing to regulate fossil fuel production, consumption, subsidies, or exploration licensing.
Confirmed that countries such as the United States, even if withdrawn from the Paris Agreement, remain bound under customary international law. It also clarified that major emitting countries like China and India are not exempt from these obligations based on outdated claims of “developing country” status; their responsibilities depend on current circumstances.
Affirmed that the Right to a Clean, Health, and Sustainable Environment is a Human Right, emphasising that this right is essential to the enjoyment of other fundamental Human Rights, including the Rights to Life, Health, Food, Water, housing, and an adequate standard of living. It concluded that States cannot fulfill their Human Rights obligations without also protecting the environment, as the two are inextricably interdependent.
Unprecedentedly, the Court ruled that States rendered uninhabitable by sea level rise will retain their statehood and maritime entitlements under international law, even if their populations are permanently displaced. Furthermore, States are not required to update their charts or list of geographical co-ordinates to determine the outer limit of their Territorial Seas and EEZs.
The simultaneous release of Advisory Opinions by ITLOS, IACtHR and ICJ offers a powerful and coordinated interpretation of State obligations on climate change. Together, they strengthen the legal legitimacy and enforceability of climate duties across multiple legal regimes, including international law, the Law of the Sea, and human rights law, and reinforce the universality of climate obligations. These opinions make clear that climate change is not an isolated issue but one that intersects with environmental protection, Ocean governance, and human rights. By addressing principles of equity, such as intergenerational equity and the Right to a Healthy Environment, they also contribute to redefining what fairness means in global governance.
What can we expect going forward?
The delivery of these landmark Advisory Opinions signals a shift in the role of international law in confronting the triple planetary crises. These Advisory Opinions carry significant legal authority, moral weight and political influence.
In their wake, States will be expected to align their laws, policies, and climate actions with these clarified obligations. States that fail to act, or act in bad faith, may face increased litigation, including new contentious cases or complaints before international courts, regional human rights bodies or domestic courts. These actions could be brought by affected States, Indigenous communities, youth, or even guardians representing the interests of Nature and marine species. The reputational cost of inaction or noncompliance has now risen substantially.
The success of these climate-related Advisory Opinions has opened the door for a new wave of legal clarification particularly in the realm of marine protection, where obligations are often fragmented, overlooked, or or poorly understood. These proceedings not only strengthen Environmental and Ocean governance and legal frameworks but also deepen their integration with human rights law. In doing so, they reinforce the rights of Indigenous peoples, coastal and Ocean-dependent communities, youth, and future generations, whose identities, livelihoods, and well-being is intrinsically tied to the health of the Ocean.
The Ocean and climate are inextricably linked
The Ocean is not separate from the climate crisis. It is central to it. Ocean and climate systems are deeply interconnected, and any serious response to climate change must include the protection and restoration of Ocean health. Yet efforts to protect the Ocean have long been undermined by fragmented legal regimes, weak enforcement, and enduring legacies of colonial governance. Despite decades of commitments, Ocean degradation continues, not because of a lack of legal obligations, but because of failures in interpretation, enforcement, and accountability.
Ocean protection is not just an environmental concern, but a question of governance, justice, and effective climate action. Without enforcing existing obligations, even the most ambitious new treaties will fall short. Because States are hesitant to bring legal action against one another due to concerns about diplomatic relations, Advisory Opinions serve as a vital, non-confrontational tool. They are now central to enforcing international law, protecting the Ocean, and advancing climate justice.
At Ocean Vision Legal, through our dedicated Ocean Litigation Department, we are committed to working at the intersection of Ocean, climate and human rights law, and enforcing existing legal obligations. Sign up for our newsletter to stay informed on our projects and advancements in this space.
"By demonstrating that even the smallest voices can influence the largest legal institutions, we hope to inspire a new generation of climate leadership — one that leverages international law as a tool of protection, not just protest.
In closing, let us be clear: this Advisory Opinion is not an endpoint. It is a catalyst. A catalyst to transform law into leverage. Principles into protection. And hope into hard-won justice.
Let the law be not a shield for polluters, but a sword for the vulnerable.”
Ralph Regenvanu, Vanuatu Member of Parliament, Keynote Speech at ‘Defending our Oceans through International Law’ UNOC3 Side Event.
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