The United Nations’ top court in a landmark advisory opinion Wednesday said countries could be in violation of international law if they fail to take measures to protect the planet from climate change, and nations harmed by its effects could be entitled to reparations.

Advocates immediately cheered the International Court of Justice opinion on nations’ obligations to tackle climate change and the consequences they may face if they don’t, The Associated Press reports.

“Failure of a state to take appropriate action to protect the climate system… may constitute an internationally wrongful act,” court President Yūji Iwasawa said during the hearing. He called the climate crisis “an existential problem of planetary proportions that imperils all forms of life and the very health of our planet.”

The non-binding opinion, backed unanimously by the court’s 15 judges, was hailed as a turning point in international climate law.

Notably, AP adds, the court said a “clean, healthy, and sustainable environment” is a human right. That paves the way for other legal actions, including states returning to the ICJ to hold each other to account as well as domestic lawsuits, along with legal instruments like investment agreements.

The advisory opinion “reflects a growing global consensus among judges that governments have legal responsibilities to address climate change,” said Ecojustice lawyer Fraser Thomson. “Increasingly, opinions like these give hope to our clients in the precedent-setting Mathur case—and to all Canadians—that it’s only a matter of time before our courts recognize that governments who fuel the climate crisis are violating the Canadian Charter of Rights and Freedoms.”

Opinion ‘Gives Legal Wings’

Reaction poured in in the hours following Iwasawa’s two-hour statement.

“You could hear a pin drop—not just in the Great Hall of Justice, but across thousands of homes, classrooms, and offices around the world tuned in to watch,” wrote former UN climate secretary Christiana Figueres, one of the key architects of the 2015 Paris climate agreement. The result was “the most far-reaching legal statement ever made on the responsibility of states to protect the rights of current and future generations to a clean, healthy, and sustainable environment,” and “the clearest legal affirmation to date that cooperation among states to address climate change is not optional—it is a binding obligation.”

“I confess I am writing through tears,” Figueres added on LinkedIn. “The road ahead remains steep. But today’s advisory opinion gives legal wings to countless efforts already under way—and to many more to come. We now walk forward not just with moral clarity, but with judicial affirmation.”

All of those factors made Wednesday “a day for the history books,” she concluded. “And a day for renewed resolve.”

The case was led by the Pacific island nation of Vanuatu and backed by more than 130 countries, AP writes. All UN member states, including major greenhouse gas emitters like the United States and China, are parties to the court.

“The ICJ’s decision brings us closer to a world where governments can no longer turn a blind eye to their legal responsibilities,” said Vishal Prasad, director of Pacific Islands Students Fighting Climate Change. “It affirms a simple truth of climate justice: Those who did the least to fuel this crisis deserve protection, reparations, and a future.”

Ralph Regenvanu, Vanuatu’s minister for climate change, called the ruling a “very important course correction in this critically important time. For the first time in history, the ICJ has spoken directly about the biggest threat facing humanity.”

He said the ruling exceeded his expectations. “I didn’t expect it to be good. It’s good. And it did go above and beyond,” he told reporters in The Hague.

“We now have a common foundation based on the rule of law, releasing us from the limitations of individual nations’ political interests that have dominated climate action,” Regenvanu added in a statement. “This moment will drive stronger action and accountability to protect our planet and peoples.”

‘The Tables Have Turned’

Climate activists had gathered outside the crowded court with a banner that read: “Courts have spoken. The law is clear. States must ACT NOW.” They watched the ruling on a giant screen, clapping and cheering at times during the two-hour hearing.

UN Secretary-General António Guterres welcomed the “historic” advisory opinion.

“This is a victory for our planet, for climate justice, and for the power of young people to make a difference,” he said in a statement. “Young Pacific islanders initiated this call for humanity to the world. And the world must respond.”

“Today, the tables have turned. The world’s highest court provided us with a powerful new tool to protect people from the devastating impacts of the climate crisis—and to deliver justice for the harm their emissions have already caused,” former UN high commissioner for human rights Mary Robinson said in a statement.

“This opinion should serve as a clarion call to governments and institutions stalling the fossil fuel phaseout,” said Kumi Naidoo, president of the Fossil Fuel Non-Proliferation Treaty Initiative. “The ICJ has affirmed what we have long known—that states have a legal duty to protect people and the planet from the impacts of the climate crisis, including taking appropriate action to prevent harm from fossil fuels.”

“This ruling confirms that governments and corporations have a legal duty to prevent further harm, uphold the right to health, and safeguard future generations,” added Dr. Jeni Miller, executive director of the Global Climate and Health Alliance. “From deadly heat and toxic air to disease and displacement, the Court’s message is clear—human health is not collateral damage.”

Vulnerable Island Nations Led the Fight

In 2023, after years of lobbying by vulnerable island nations who fear they could disappear under rising sea waters, the UN General Assembly asked the IJC for an advisory opinion, an important basis for international obligations, AP recalls.

Its panel was assigned two questions: What are countries obliged to do under international law to protect the climate and environment from human-caused greenhouse gas emissions? And what are the legal consequences for governments when their acts, or lack of action, have significantly harmed the climate and the environment?

“The stakes could not be higher. The survival of my people and so many others is on the line,” Arnold Kiel Loughman, attorney general of the island nation of Vanuatu, told the court during a week of hearings in December.

In the decade up to 2023, sea levels rose by a global average of around 4.3 centimetres, with parts of the Pacific rising higher still. The world has also warmed 1.3°C since pre-industrial times, primarily because of the burning of fossil fuels.

Now, “we will now take the ICJ ruling back to the United Nations General Assembly, and pursue a resolution that will support implementation of this decision,” Regenvanu said Wednesday. “Even as fossil fuel expansion continues under the United States’ influence, along with the loss of climate finance and technology transfer, and the lack of climate ambition following the U.S.’s withdrawal from the Paris Agreement, major polluters—past and present—cannot continue to act with impunity and treat developing countries as sacrifice zones to further feed corporate greed.”

Ruling Could Be Leverage at COP30 Climate Conference

Activists could bring lawsuits against their own countries for failing to comply with the decision [pdf], which ran over 130 pages.

Erika Lennon, senior attorney at the U.S. Center for International Environmental Law, said the ruling also can be used as leverage at the next UN climate conference later this year in Belém, Brazil.

“States must take this ICJ ruling and use it to advance ambitious outcomes at COP30 and beyond,” she told AP. “People and the planet deserve it.”

The United States and Russia, both major petroleum-producing states, are staunchly opposed to the court mandating emissions reductions. The Trump administration has again withdrawn the U.S. from the 2015 Paris climate agreement and has made it harder to find scientific assessments of how climate change endangers the U.S. and its people.

Asked to comment on the ruling, White House spokesperson Taylor Rogers said: “As always, President Trump and the entire administration is committed to putting America first and prioritizing the interests of everyday Americans.”

Simply having the UN court issue an opinion is the latest in a series of legal victories for the small island nations, AP writes. Earlier this month, the Inter-American Court of Human Rights found that countries have a legal duty not only to avoid environmental harm, but also to protect and restore ecosystems. Last year, the European Court of Human Rights ruled that countries must better protect their people from the consequences of climate change.

In 2019, the Netherlands’ Supreme court handed down a major legal win for climate activists when judges ruled that protection from the potentially devastating effects of climate change was a human right and that the government has a duty to protect its citizens.

ICJ President Iwasawa acknowledged Wednesday that international law had “an important but ultimately limited role in resolving this problem,” adding that a lasting solution will need the contribution of all fields of human knowledge “to secure a future for ourselves and those who are yet to come.”

Major segments of this story were published by The Associated Press and republished by The Canadian Press on July 23, 2025.