Daily Debrief 23 July 2025

Aug 28

In a nutshell

This Debrief is a continuation of the Daily Debriefs sent out during the hearings for this advisory opinion i n December 2024. It’s provided by the World’s Youth for Climate Justice, the Center for International Environmental Law, the Pacific Islands Students Fighting Climate Change, and volunteers from the AO Alliance.

A Historic Legal Breakthrough - Today’s advisory opinion marks a watershed moment in international climate law, delivering unprecedented legal clarity on States’ obligations. Unanimously adopted by all 15 judges of the world’s highest court, the ruling draws on binding international norms—its authority is undeniable. The Court delivered a clear roadmap to hold polluters accountable under multiple sources of international law, extending beyond the climate treaties, and secure the right to remedy and reparation.
No More Excuses for Polluters - Despite efforts by polluters to evade responsibility, the Court rejected every legal loophole. It reaffirmed a basic truth: the law applies to all, and those who knowingly harm other nations’ territories can and will be held accountable. For the first time, fossil fuels—long a taboo in intergovernmental negotiations—were directly addressed. The Court was clear: failing to phase out production, consumption, and eliminate subsidies of fossil fuels is indefensible.
Legal Clarity Fuels Legal Action - This decision sharpens the legal tools available to hold actors accountable. It will boost pending climate cases and inspire new ones seeking justice and compensation for climate damage. A Turning Point for Global Climate Governance - Governments must act. COP30 and upcoming multilateral forums are critical opportunities to reset climate governance on a foundation of justice, accountability, and reparations.
Reaffirmation of the Right to a Healthy Environment - The 15 judges of the Court seized the opportunity to reaffirm the right as a binding norm of international law and a precondition for the enjoyment of many other human rights. A David vs. Goliath Victory - This is the law standing with the climate vulnerable. What began as a student-led initiative in the Pacific has become a global reckoning—a new era of legal power for peoples and communities on the climate frontlines.
A Win for Us All - This isn’t just a victory for Vanuatu or Pacific youth—it’s a win for everyone facing the fallout of climate inaction and corporate recklessness

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Today’s reactions

Quotes can be used by journalists for their reporting. For questions or follow up, please reach out to Quint van Velthoven at quint@wy4cj.org.
“Today the world’s smallest countries have made history. The ICJ’s decision brings us closer to a world where governments can no longer turn a blind eye to their legal responsibilities. It affirms a simple truth of climate justice: those who did the least to fuel this crisis deserve protection, reparations, and a future. This ruling is a lifeline for Pacific communities on the frontline.”
- Vishal Prasad (29), Fiji, Director, Pacific Islands Students Fighting Climate Change.
“This moment shows how youth and Global South communities have the power to shape international law and seek reparation for damage done.”
- Nicole Ponce (31), Philippines, Global Advocacy Lead, World’s Youth for Climate Justice.

Outside the Court

Today, youth and civil society from all over the world gathered outside the Court for a solidarity demonstration while awaiting the delivery of the advisory opinion. The demonstration included musical performances, poetry, and speeches. Each contribution highlighted the importance of this historic moment and the necessity to deliver justice for communities most impacted by the climate crisis. At the end of the mobilisation, the demonstrators assembled to watch the reading of the opinion on a screen in front of the Peace Palace. They cheered along each powerful line delivered by the judges.

The day before, on July 22, a screening of the documentary, YUMI - The Whole World, was organised at the Flora Film Theatre. This moment allowed campaigners on the ground to convene, relive the story of how these proceedings were born out of the vision of students in the South Pacific and the unprecedented journey of this initiative, and find strength in each other for the day to come.

What’s next?

The International Court of Justice’s (ICJ) climate ruling provides crucial legal clarity and must now serve as a springboard for real change—ensuring accountability for major polluters, reparations for those harmed, and legal protection for people and the planet. To make climate justice a global mandate rather than a distant goal, decisionmakers and climate justice champions must urgently pursue the political and judicial pathways needed for effective implementation and enforcement, ushering in a new era of climate accountability and ambition.

The first step in this new journey initiated here in The Hague requires greater collective awareness about the key messages reaffirmed by the Court. If you would like to receive additional information and resources related to International Courts’ processes concerning climate justice, please sign-up here. We also invite you to rewatch our High-Level Rapid Reaction Panel in response to the landmark Advisory Opinion issued today by the International Court of Justice (ICJ) on climate change. This timely hybrid event will unpack the opinion’s key findings, examine its implications for international law and climate justice, and provide diplomats, civil society, and the media with rights-based analysis and framing tools. Featuring heads of state, government officials, legal experts, and civil society leaders, the panel will explore how this historic ruling can drive forward meaningful climate action and accountability

Authoritative Nature of the ICJ’s Ruling

The advisory opinion constitutes the Court’s application of States’ long-standing, legally binding obligations under international law to the context of the climate emergency. Because the ICJ is the UN’s principal judicial organ, its ruling constitutes the most authoritative source of said interpretation. Moreover, the advisory opinion comes with the overwhelming endorsement – and at the request – of States across the globe. In 2023, 132 States agreed to co-sponsor a resolution to go before the United Nations General Assembly, which then unanimously requested that the Court provide an opinion on the obligations of States to address climate change under international law and the legal consequences for failing to deliver on those obligations.

Further, that 99 States and 13 international organisations – including major climate polluters such as the United States – submitted to the Court demonstrates the authority and legitimacy of the ruling and showcases the vast support thereof by the global community. States’ active participation provided further endorsement of the advisory process and actively shaped the Court’s interpretation. At its core, as an advisory opinion from the world’s highest court, the Court’s conclusions come with great legal force and legitimacy. In unanimously finding that States have an obligation to drastically reduce their emissions, the Court has provided decisive legal guidance to States, policymakers, judiciaries, and civil society across the globe on climate change. The authoritative nature of these conclusions is further reflected in the diversity of binding international legal sources that the Court drew from, and to which States have already committed. In so doing, the Court has left no room for ambiguity regarding the duty that States have to protect the climate system and repair the harm done.

Analysis of key themes addressed in the Advisory Opinion (AO)

Legal Sources of States’ International Obligations

States’ obligations under international law concerning climate change extend beyond the specific climate treaties including, but not limited to, customary duties to prevent transboundary harm and to cooperate, the UN Convention on the Law of the Sea, the Convention to Combat Desertification, the Convention on Biological Diversity, and the International Covenants on Civil and Political Rights, and Economic, Social and Cultural Rights. All obligations stemming from these sources must be interpreted and applied in a coherent, systematic way.

The UN Framework Convention on Climate Change (UNFCCC), Kyoto Protocol, and Paris Agreement are complementary: the UNFCCC sets objectives and principles, while the others translate these into concrete obligations. The Paris Agreement commits States to ambitious emissions targets and operationalises differentiated responsibilities, requiring ongoing mitigation and adaptation efforts.

Crucially, the Court explained that treaty and customary rules mutually inform each other, and that the climate change treaties do not exclude the application of other rules of international law.

With regards to the applicable law regarding legal consequences for breaching these obligations, the Court reaffirmed the applicability of the law of State responsibility. Cooperation mechanisms under the climate change treaties, including the Loss and Damage Fund and the Paris Agreement Implementation and Compliance Committee, while important for implementation and cooperation, do not override the established international law of State responsibility.

Substantive Obligation of States: the Duty of Care and the Principle of Prevention

Due diligence is guided by the principles of equity and common but differentiated responsibilities and respective capabilities, is informed by the best available science, and may evolve over time. All States must use the means at their disposal to discharge this duty; however, as States develop economically and their respective capacity increases, what is required of them under due diligence increases accordingly. Due diligence demands “appropriate rules and measures,” including “regulatory mitigation mechanisms” designed to achieve the “deep, rapid, and sustained reductions of GHG emissions” needed to protect the climate system. Procedurally, due diligence requires that States carry out environmental impact assessments (EIAs) particularly for significant proposed individual activities contributing to greenhouse gas (GHG) emissions under their jurisdiction or control (including those of private actors), and notify and consult in good faith with other States about the potential adverse impacts of these activities. With respect to EIAs, the Court notes that climate assessments may include consideration of the “possible downstream effects” of the proposed activities.

A State that does not exercise due diligence in the performance of its primary obligation to prevent significant harm to the climate system commits an internationally wrongful act entailing its responsibility.

Human Rights Obligations including the Right to a Healthy Environment

The Court strongly asserted that States must take ambitious actions to protect the environment, and the climate system in particular, in order to guarantee the effective enjoyment of human rights. It reiterated that the environment “is the foundation for human life, upon which the health and well-being of both present and future generations depend.” The Court further affirmed that the degradation of the climate system and other parts of the environment impairs numerous human rights including, but not limited to: the rights to life, health, and adequate standard of living, including access to food, water, and housing, and privacy, family, and home, as well as the rights of women, children, and Indigenous Peoples.

Given the far-reaching recognition of the right to a clean, healthy, and sustainable environment (R2HE) in national, regional, and international instruments, the Court affirmed the right as a binding norm of international law and a precondition for the enjoyment of many other human rights. In relation to States’ human rights obligations, “it is difficult to see how these obligations can be fulfilled without at the same time ensuring the protection of the right to a clean, healthy and sustainable environment as a human right.”

Underscoring the urgent and existential threat posed by climate change, the Court asserted that the environment must be protected for present and future generations. Therefore, States must pay due regard to the interests of future generations in fulfilling their obligations under international law in light of the guiding principle of intergenerational equity. The latter, according to the Court, expresses “the idea that present generations are trustees of humanity tasked with preserving dignified living conditions and transmitting them to future generations.”

Substantive Obligation of States: the Duty of Care and the Principle of Prevention

The customary international law duty to prevent transboundary environmental harm is fully applicable with respect to the climate system. Because climate change poses a scientifically demonstrated indisputable risk to all States, this obligation must be performed under a stringent due diligence standard, which demands a heightened degree of vigilance and prevention. Due diligence is guided by the principles of equity and common but differentiated responsibilities and respective capabilities, is informed by the best available science, and may evolve over time. All States must use the means at their disposal to discharge this duty; however, as States develop economically and their respective capacity increases, what is required of them under due diligence increases accordingly.

Due diligence demands “appropriate rules and measures,” including “regulatory mitigation mechanisms” designed to achieve the “deep, rapid, and sustained reductions of GHG emissions” needed to protect the climate system. Procedurally, due diligence requires that States carry out environmental impact assessments (EIAs) particularly for significant proposed individual activities contributing to greenhouse gas (GHG) emissions under their jurisdiction or control (including those of private actors), and notify and consult in good faith with other States about the potential adverse impacts of these activities. With respect to EIAs, the Court notes that climate assessments may include consideration of the “possible downstream effects” of the proposed activities.

Obligations related to Fossil Fuels and the Regulation of Corporate Actors

States are obligated to prevent climate harm and failing to curb production and use of fossil fuels the main driver of the climate crisis–may violate international law. In reaffirming the IPCC as best available science, the Court acknowledged that burning fossil fuels, which results from their exploration, production, and use, is a leading cause of climate change. Under customary international law, States have a duty to prevent significant harm to the environment and that duty applies to the climate system and must be fulfilled by acting with due diligence. Thus, the ICJ confirms that States must take action to halt climate change by deploying appropriate measures to achieve deep, rapid, and sustained reductions of GHG emissions, including by regulating the conduct of public and private operators within their jurisdiction or control, with effective enforcement and monitoring. Furthermore, private actor conduct may be attributed to States where they have failed to regulate corporate conduct sufficiently in line with their due diligence obligation.

In assessing the questions before it, the Court also noted that relevant conduct was not limited only to actions that directly result in GHG emissions, but that the scope of conduct encompasses a full range of activities, such as policymaking, licensing, and subsidising, that contribute to the climate crisis. Thus, the failure to adopt appropriate measures to protect the climate, including, but not limited to, halting the production, consumption, exploration licensing, or subsidisation of fossil fuels, may constitute an internationally wrongful act and is subject to further legal consequences.

As these duties emerge also from customary international law, they apply to all States regardless of whether they are parties to the UN climate agreements, which is but one source of law applicable to the climate crisis.

Continued Statehood in Spite of Sea Level Rise and Climate Change-Induced Displacement

The Court found that sea level rise does not legally affect the maritime borders of States, nor their territorial integrity and statehood. Under the UN Convention on the Law of the Sea (UNCLOS), State Parties are obligated to openly and formally communicate the external limits of their territorial seas and exclusive economic zones (EEZ). According to the Court, once they have done so, State Parties to the treaty are not required to update these geographic boundaries in spite of physical changes to their coastlines arising from sea level rise and other climate change-related impacts. Likewise, even if the effects of climate change result in the complete loss of a State’s territory and the displacement of its population, “a strong presumption in favour of continued statehood should apply.” This means that the State would continue to exist subject to rights and protections owed to it under international law.

In addressing climate change-induced displacement, the Court affirmed the relevance and application of the customary international law principle of non-refoulment, which guarantees that no individual shall be returned to a country where they would face irreparable harm to their right to life. Accordingly, when the impacts of climate change endanger the lives of individuals and lead them to seek safety in another country, States have an obligation to not return them back to their country of origin.

Consequences of Violating Legal Obligations: Cessation, Non-Repetition, Reparation, and Compensation

Any breach of legal obligations by a State in the climate context triggers the full suite of legal consequences under the international law of State responsibility. Attribution is straightforward – a State is responsible for its organs’ conduct and for private actors if it fails to exercise due diligence. Although GHG emissions are cumulative, each State’s contribution can be scientifically determined, allowing multiple injured States to invoke responsibility. Because obligations protecting the atmosphere and high seas (global commons) and obligations under climate treaties’ are owed to all other states (“erga omnes partes”), any State may demand cessation, guarantees, or reparation, even if it is not directly injured.

Under the duty of performance, the responsible State must continue fulfilling its obligations despite the breach, for example, by adopting revised mitigation measures or enhancing carbon sinks. Cessation and assurances of non repetition requires that wrongful conduct, such as excessive emissions or harmful subsidies, must cease and any inconsistent administrative measures or legislation must be revoked. Where damage materialises, the State must make full reparation through restitution, compensation, and satisfaction. Restitution may serve to restore the situation before the violation of international law, such as reconstructing infrastructure or rehabilitating ecosystems, and compensation covers financially assessable losses. Satisfaction may take the form of expressions of regret, formal apologies, public acknowledgments, or education of the society about climate change.

Important Notice: This Daily Briefing is a rapid, topline analysis of the International Court of Justice’s Advisory Opinion. It provides critical elements for context to understand the significance of key aspects of the Court’s authoritative judicial ruling. This briefing is not meant to be legal advice and does not give a comprehensive summary of the advisory opinion. Please refer to the advisory opinion document for the full, original text.

The editors of today’s Daily Briefing are Aditi Shetye, David Boyd, Erika Lennon, Henrieke Bünger, Joe Udell, Joie Chowdhury, José Daniel Rodríguez Orúe, Katharina Maier, Louise Fournier, Nikki Reisch, Sébastien Duyck, Theresa Amor-Jürgenssen, and Upasana Khatri.

Our deepest gratitude to Linn Pfitzner for assisting us with taking notes during the reading of the opinion.

Roza de Jong