The ICJ's ruling on climate change: A pivotal moment for global action and justice
The International Court of Justice's (ICJ) ruling in July 2025 has sent shockwaves through the global climate movement, marking a pivotal moment in the fight against climate change. The court's decision, unanimously agreed upon, declared that all states are legally bound to address the human-made climate crisis, which poses an "urgent and existential threat" to the planet's life-sustaining systems and, consequently, humanity itself.
This ruling is not just a landmark in itself; it builds upon a growing body of legal precedents from climate lawsuits worldwide. The ICJ's opinion adds weight to decisions made by the Inter-American Court of Human Rights and the International Tribunal on the Law of the Sea, further solidifying the legal basis for climate action.
The ICJ case, in particular, is seen as a game-changer, bringing the world's most pressing issue to the highest court in the world. It clarifies that the established legal duty to do no harm, especially transboundary environmental harm, is universal and not contingent on a country's ratification or membership of formal treaties like the Paris Agreement, from which Donald Trump withdrew on his first day back in the White House.
As the COP30 summit begins, 25 UN experts, including special rapporteurs on climate change, Indigenous peoples, and education, are expected to release a joint statement calling for "full compliance" with the ICJ ruling. They advocate for a ban on fossil fuel lobbyists and increased transparency as crucial steps towards achieving just climate action.
The statement emphasizes the need for meaningful outcomes at COP30, particularly in terms of mitigation and international financial and technological cooperation. It highlights fossil fuels and related subsidies as the main drivers of climate change and their impacts on human rights, including health, economic equality, adequate living standards, education, and cultural rights.
The question arises: What impact will the ICJ opinion have on negotiations and domestic climate policies? Can international tribunals compel governments to take the transformative action needed to prevent catastrophe? Can affected communities and countries obtain resources and remedies from polluters for the devastating climate harms they face, such as rising sea levels, melting glaciers, deadly heatwaves, and destructive storms like Hurricane Melissa, which battered Jamaica in late October?
The ICJ advisory opinion affirms that all states have legal duties to act with due diligence to prevent, mitigate, and remedy climate-related harms. However, the onus is on industrialized wealthy countries that have contributed most to the crisis to take the lead. States must cooperate in good faith and in accordance with their common but differentiated responsibilities and capabilities (CBDR), a principle that has been at the heart of discussions, disagreements, and delays in the past 30 years of UN climate summits.
Crucially, the judges rejected arguments from high-polluting countries opposing the ICJ case, including the US, UK, China, the EU, Russia, and Saudi Arabia, that their obligations were limited to the consensus-based climate regime, such as the UN Framework Convention on Climate Change, Kyoto Protocol, and Paris Agreement.
The ICJ affirmed that every person has a human right to a "clean, healthy, and sustainable" environment, a prerequisite for enjoying universal foundational rights like life, health, food, water, and housing. As such, the legal duty to prevent climate catastrophe flows from the entirety of international law, including the UN Charter and universal obligations under customary law that obliges all states to prevent serious transboundary harm to the environment and human rights from activities within its borders.
Could the ICJ ruling be the catalyst for policy change at COP30? On mitigation, the ICJ ruling elevates 1.5C from an aspirational target to a definitive legal benchmark, holding states legally accountable. It requires countries to ensure their Nationally Determined Contributions (NDCs) reflect the "highest possible ambition" and CBDR.
However, COP is a multilateral process where decisions are made by consensus, a fact that has allowed powerful countries to veto or block decisions they dislike by exerting pressure on smaller states dependent on them for aid. Some big-emitting states have attempted to discredit the ICJ ruling as radical and downplay its significance.
According to Jacob Werksman, the EU's head of delegation, speaking in a personal capacity during a New York Climate Week event in September, the ICJ ruling could have a "chilling effect" or no impact at all on negotiations that should remain "laser-focused on emissions reductions".
Despite this, the majority of states and legal experts agree that the business-as-usual carbon tunnel position goes against the legality and spirit of all three international tribunal decisions and will be increasingly challenged in domestic and international courts.
Ralph Regenvanu, the climate minister of Vanuatu, which spearheaded the ICJ case, emphasized the need for climate-vulnerable states to be ready to counter efforts by polluting states to dilute the ICJ advisory opinion in public discourse. He stressed that cooperation is a legal obligation, not charity or aid, and that failing to fulfill what was agreed in Paris and at every COP is an internationally wrongful act.
Vanuatu and other small island states facing existential threats from the climate crisis and fossil-fuel-related harms are expected to speak out about the ICJ ruling throughout the summit. Many countries are likely to limit public comments for diplomatic reasons but have been busy seeking legal advice on how the ICJ opinion can strengthen their position during closed-door negotiations on mitigation, adaptation, and climate finance, including loss and damage.
The F-words: Fossil fuels
The ICJ provided the boldest language on fossil fuels, explicitly stating the legal obligation for states to exercise "due diligence" in ending extraction, consumption, licenses, and subsidies due to the overwhelming evidence of harms caused to all life-supporting systems, including climate, food, water, and biodiversity.
This duty extends to regulating private businesses responsible for emissions and other significant climate system harms operating within their borders. A state's failure to regulate these greenhouse gas emissions and emitters constitutes an internationally wrongful act susceptible to legal consequences.
Elisa Morgera, the UN Special Rapporteur for Climate Change, stated that after the clarity of the ICJ advisory opinion, a meaningful decision on fossil fuels is essential for the COP process to remain legitimate.
The industry will likely be out in full force at COP30, especially as the host, Brazil, recently slashed environmental regulations, opening the door for more oil extraction in the Amazon. Expect industry-sponsored misinformation and disinformation targeting the ICJ ruling, a strategy they have successfully employed over decades to block and delay climate action.
Support for affected countries
The ICJ ruling clarifies the obligation of rich global north states to rapidly phase out fossil fuels to prevent further loss and damage and to provide financial and technical support to global south states for adaptation, minimizing harm and responding to irreversible loss and damage. While the Inter-American Court on Human Rights included a strong ruling on reparations, the ICJ did not.
It validates and supports claims for reparations for harm caused to life-sustaining climate systems by states and the corporations they are legally obliged to regulate but leaves it up to individual communities or states to seek legal remedy through litigation.
Activists in Belém will harness the ICJ ruling to demand climate justice, according to Harjeet Singh, an Indian climate activist, COP veteran, and strategic adviser to the Fossil Fuel Non-Proliferation Treaty. He emphasizes that the ICJ advisory opinion is a lever to demand reparations and justice in a different manner than before, but for that to happen, public opinion is crucial.
Singh highlights the responsibility of fossil fuel companies and the need for governments to regulate and be held liable for damages. He argues that international law supports this, and COP30 is an opportunity for the climate justice movement, scientists, and the media to build a public narrative around reparations for historical injustice. People on the street should know that the ICJ decision exists and their governments are not complying with the law.
What the ICJ ruling didn't do
The decision skirted around accountability and climate finance, leaving it up to communities and individual states to prove in court that a state had breached international obligations. It did not lay out a more stringent framework of enforcement or address the challenge posed by global heating to development for global south countries.
However, the ICJ advisory opinion is already reshaping domestic and transnational climate litigation, with claimants and courts from Canada to Brazil, Switzerland to South Korea, drawing on its reasoning, signaling a shift from legal theory to action.
Adam Weiss, Chief Programs and Impact Officer at ClientEarth, stated that the ICJ told us the international legal system cannot continue to allow profit from digging up and burning fossil fuels. He believes we are at a legal tipping point, and the law will be the power that forces us in the direction we need to go.
