Through its advisory opinion that declares that states are legally obliged to protect the environment and are bound to compensate for the climate/environment harms caused by their actions, the International Court of Justice (ICJ) has struck a monumental blow for the global fight for climate justice
On July 23, 2025, the world’s highest court ruled that it is not sufficient to simply follow some treaties, such as the Paris Agreement, but that states and major polluters are bound, under international law, to drastically reduce emissions, prevent serious harm to vulnerable groups, and provide reparations to frontline communities already bearing the brunt of climate change caused by their negligent actions.
“Greenhouse gas emissions are unequivocally caused by human activities which are not territorially limited,” said ICJ President Yuji Iwasawa as he read the advisory opinion at the Peace Palace, the court’s seat in The Hague, the Netherlands.
In effect, the opinion clarified that climate harm is a legal failure that can, therefore, be addressed by the legal system.
The ICJ’s opinion connects climate change to international human rights law by asserting communities’ right to a safe environment. It acknowledges the increasing dangers of climate change, such as rising sea levels and temperatures, and their devastating effects on food and water security, which threaten communities’ fundamental rights, including the right to life and housing.
“The human right to a clean, healthy and sustainable environment is essential for the enjoyment of other human rights,” Judge Iwasawa emphasised.
For decades, frontline communities, particularly in the Pacific Islands, have borne the brunt of increasingly devastating climate impacts. Vanuatu, a small archipelago nation battered by severe cyclones and rising seas, has long championed international accountability for climate harm. What began as a bold initiative launched by law students from the University of the South Pacific in 2019 and championed by Vanuatu through the United Nations system has now culminated in a decisive legal milestone that promises to reshape climate governance worldwide.
The Pacific Islands Students Fighting Climate Change (PISFCC) and the World’s Youth for Climate Justice (WYCJ) conceived the idea in 2019, eventually uniting over 1,500 organisations worldwide and securing unprecedented support from UN member states.
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“Today the world’s smallest countries have made history,” said Vishal Prasad, Director of PISFCC. “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.”
The journey from student idea to international law began when Vanuatu’s government, under former Prime Minister Bob Loughman, announced in September 2021 that it would pursue the option of the ICJ advisory opinion.
Working with Blue Ocean Law, a Guam-based firm, Vanuatu assembled an international legal team and appointed two special envoys for climate change: Ambassador Odo Tevi to focus on UN missions in New York and Ambassador Bakoa Kaltongga to garner support from Pacific leaders and other regions.
The breakthrough came through the creation of the ICJAO4 Climate Core Group, comprising 18 states representing all UN regions with varying interests and development levels. This inclusive approach proved crucial in building the broad coalition needed for success.
Through consultation processes, multiple draft revisions, and several bilateral meetings, Vanuatu and its allies demonstrated respect for the diplomatic process while maintaining unwavering focus on their goal. The strategy paid off when the final resolution of the United Nations General Assembly was co-sponsored by 132 states, far exceeding the simple majority needed and ensuring the adoption by consensus of resolution 77/276 on March 29, 2023.
This came soon after Vanuatu experienced the devastating effects of Category 4 tropical cyclones Judy and Kevin in early March 2023, along with major earthquakes, forcing the government to declare a six-month state of emergency. The UN Secretary General requested the ICJ advisory opinion on April 12, 2023.
The General Assembly asked the ICJ judges to consider two questions: What are countries’ obligations under international law to protect the climate from greenhouse gas emissions? What are the legal consequences for countries that harm the climate system?
Court establishes new legal framework
In its July 2025 advisory opinion, the ICJ established several groundbreaking legal principles that will fundamentally reshape international climate obligations. It declared that international law demands more than voluntary commitments, requiring states to implement obligations under human rights law, environmental law, and treaty commitments “together and harmoniously.”
States and major historical polluters now have confirmed legal obligations to cut emissions, prevent serious harm, and protect vulnerable populations both within and beyond their borders. These duties extend to fossil fuel consumption, extraction, expansion, and subsidies, applying even to states not party to climate treaties and private entities within their jurisdiction.
The court recognised that decisions must be guided by the best available science, particularly the reports of the Intergovernmental Panel on Climate Change (IPCC), with the Paris Agreement’s 1.5°C temperature limit serving as the legal reference point for sufficient action and responsibility.
“Governments are legally required to protect the rights to life, health, a healthy environment, and self-determination from climate harm. The opinion mandates special attention for Indigenous Peoples, Small Island Developing States, youth, and future generations,” the advisory opinion said.
Perhaps most significantly, the ICJ affirmed that states with high historical and current emissions have heightened obligations to remedy climate harm through reparations, support, and regulation of private actors.
It is not clear what effect the actions of climate change deniers will have on the effectiveness of the ICJ opinion. The United States, one of the world’s biggest historical greenhouse gas emitters, has, under President Donald Trump, moved swiftly to undo major climate and environmental policies instituted by previous administrations. It has shrugged off the impacts of climate change despite the US suffering from severe storms, flooding, and heat waves.
“President Trump and the entire administration are committed to putting America first and prioritising the interests of everyday Americans,” White House spokeswoman Taylor Rogers told Reuters when asked to respond to the advisory opinion.
Youth movement celebrates historic victory
However, this has not downplayed the significance of the ICJ declaration on the communities affected by the impacts of 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, Global Advocacy Lead for World’s Youth for Climate Justice, commented on the broader significance of the ruling.
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Jule Schnakenberg, Executive Director of World’s Youth For Climate Justice, echoed her sentiments.
“International courts around the world have spoken loud and clear: climate harms must be avoided and reparations must be paid where damages have been caused. The alignment amongst these international courts demonstrates a unified understanding that the climate crisis threatens fundamental human rights.”
The advisory proceedings saw record-breaking participation, with more than 96 states and 11 international organisations contributing. The legal process was accompanied by a People’s Assembly in The Hague, where community leaders, Indigenous Peoples, youth activists, and climate witnesses shared their stories and collective demands for justice through the People’s Petition.
Cynthia Houniuhi, President of PISFCC, said the ruling must now translate into policy.
“Now, the world’s highest court has confirmed what the youth and frontline communities have long demanded: bold climate action rooted in justice. The ICJ’s ruling is a powerful signal that the law is on our side. It must now guide not only courtrooms, but climate negotiations and policy decisions worldwide.”
The ICJ opinion joins a growing body of international legal decisions strengthening climate obligations. The Inter-American Court of Human Rights recently issued Advisory Opinion 32/25, confirming states’ binding obligations to prevent irreversible climate harm. Earlier in 2024, the International Tribunal for the Law of the Sea ruled that greenhouse gas emissions constitute marine pollution under international law.
“Pacific island states and students, the youth movement, and the global majority that aligned behind them have given the world a master class in advocacy for climate justice. This day marks a win for people over polluters,” said Nikki Reisch, Climate and Energy Programme Director at the Centre for International Environmental Law.
While advisory opinions are not legally binding, they carry significant moral and legal weight in international law and can influence domestic court decisions worldwide. The ruling provides powerful ammunition for climate litigation and diplomatic pressure on high-emitting countries.
The decision also validates the approach advocated by UN Secretary-General António Guterres, who was present for the original resolution adoption – an unusual occurrence that demonstrated the initiative’s importance. As he noted at the time: “There is nothing more powerful than an idea whose time has come.”
