The idea had started as a class assignment. Their professor, Justin Rose, asked them to imagine legal pathways for climate justice, and one group proposed the ICJ. It wasn’t a new idea: Pacific nations had pushed for a 1996 ICJ opinion on nuclear weapons, and in 2011, Palau floated a climate case that never gained traction. But by 2019, with both climate devastation and global awareness surging, the students believed the timing was right.

They realized the most viable route to the ICJ was through the United Nations General Assembly, which would require at least 97 votes—a daunting target for such a politically charged question. From their classroom in Suva, Fiji, they began writing letters to every Pacific Island government, as well as Australia and New Zealand, to ask for support.

Soon, the polite declines began rolling in. Some reiterated that the UN Framework Convention on Climate Change (UNFCCC) was the proper arena for climate negotiations. Others asked to be kept informed, but offered no commitment.

Only Regenvanu agreed to meet. A group of students arrived at his office—”really nervous, dressed in their best island wear”—and made their pitch. By the end of the meeting, he told them Vanuatu would back the effort. The students were stunned.

For Vanuatu, the ICJ campaign wasn’t a gamble—it was part of a broader strategy. After 30 years of pleading, pushing, demanding—and, as Regenvanu put it, “every time coming away with crumbs”—a sense of dread now accompanied each COP, the annual UNFCCC climate summit.

“We’ve got to exhaust all possible avenues because we have no choice.” From the Law of the Sea to the Rome Statute to the Fossil Fuel Non-Proliferation Treaty to the Clean Air Coalition, Vanuatu is pressing on every legal and diplomatic front. “It’s our survival,” said Regenvanu. “We need to make sure that there’s nothing we miss in this fight.”

Over the next six years, the students and Vanuatu built a global coalition. What began as a class project grew into a diplomatic campaign spanning continents. They recruited former heads of states, legal scholars, and policy experts. They staged creative acts—a music video, a flotilla in New York’s East River—to raise awareness and rally support.

In 2022, three years after introducing the initiative, the Pacific Islands Forum formally endorsed it—a major breakthrough. The students kept organizing, lobbying governments from the Caribbean to Africa to secure the votes they’d need. Some called the youth-led campaign strategically naïve; they called it stubborn optimism. In 2023, when the resolution went before the UN General Assembly (UNGA), 18 nations had stepped up as ICJ Champions, with 132 more cosponsoring. It passed by consensus. The case was headed to The Hague.

The UNGA asked the ICJ to clarify two key questions: First, what are states’ obligations to protect the climate and the environment from anthropogenic climate change, for both present and future generations? Second, what are the legal consequences for states that, through their action or inaction, cause significant harm? Put simply: What do those who caused the climate crisis owe to those suffering its consequences?

The fight wasn’t only about the outcome but also about reimagining the process. The ICJ—formal, colonial, and long shaped by “the ICJ mafia,” a cast of white-shoe lawyers and Global North diplomats—was not known for accessibility. So the ambition, explained  Vishal Prasad, the PISFCC campaign director, was to make this case “the most inclusive, participatory process ever.”

The campaign held regional convenings, gathered community testimonies, and submitted “Witness Stand” videos alongside formal legal briefs. The court received 91 written submissions—the most ever in an advisory proceeding—with many states engaging for the first time. All Pacific Island nations participated, and the hearings featured an unprecedented number of Indigenous and frontline voices.

Among them was Cynthia Rosah Bareagihaka Houniuhi, a youth leader from the Solomon Islands and the president of PISFCC. In her testimony, she spoke of the traditions of her Are‘Are people, for whom Mako, the land, is mother: “a living, timeless plane where generations past, present and future converge, interconnected and sustained in an unbroken cycle of life.” Without our land, our bodies and memories are severed from the fundamental relationships that define who we are.” It is future generations, she told the court in December, who stand to lose the most, their fate held hostage by a handful of major emitters who refuse to change course.

Not everyone shared that view. That afternoon, Saudi Arabia offered a different vision. While acknowledging the urgency of climate action, it urged the court to treat existing treaties—especially the Paris Agreement—as the final word on legal obligation, warning that going beyond them could jeopardize global cooperation. This position was echoed by others, including Australia, Germany, Canada, China, the United States, Russia, the Nordic countries, Kuwait, and the United Kingdom. In her oral argument, a 27-minute-long exercise in legal containment, US representative Margaret L. Taylor described the Paris Agreement as the most legitimate, “carefully calibrated” expression of international will.

Together these statements marked a coordinated effort—not to deny the climate crisis but to limit the legal tools to address it. A treaty long dismissed by activists for its lack of enforceability had been recast as the legal ceiling.

But the court disagreed. Today, it made clear that while the Paris Agreement allows countries flexibility in setting climate targets, that discretion has limits. National plans must still add up to something real. Governments, the court said, have a duty to  act—urgently, effectively, and with care proportionate to the crisis. That involves regulating private actors and ending harmful practices like fossil-fuel licensing and subsidies. Failure to meet this standard—even through inaction—can constitute a violation of international law.

At the heart of this case was a demand for repair: not just of ecosystems but of relationships, futures, and worlds already lost. In his oral argument before the court, Julian Aguon, a CHamoru human rights lawyer, described how Melanesian peoples have already suffered “forced dislocations from their traditional territories, loss of natural resources essential for both cultural and physical subsistence, breakdown of political systems and means of self-governance, and rupture of relationships to the cosmos.” In short, “they have lost nearly everything that has, since time immemorial, formed their very essence as peoples.”

Today’s opinion confirms that states can be held legally responsible for climate harm, including, in some cases, through full reparation. While the Loss and Damage fund—formally known as the Fund for Responding to Loss and Damage, a UN mechanism to support vulnerable countries facing irreversible climate impacts—exists in principle, it remains underfunded and largely discretionary. The court’s opinion helps shift the idea of climate reparations from moral appeal to legal obligation.

Impunity festers in legal gray zones. As the climate crisis deepens, so do efforts to obscure responsibility. Top emitters have leaned on voluntary offsets and vague net-zero pledges, tools designed to deflect accountability. But the court’s opinion now equips movements and vulnerable states with new tools to demand more than lip service.

Just after the opinion was delivered, Vanuatu’s counsel Margaretha Wewerinke-Singh explained its implications for major emitters: “Big historical polluters have been arguing they are under no obligation to make reparations—they provide it on a voluntary basis, if and when they please, as much or as little as they please. But the court has made it crystal clear: If you do not provide reparations that are, I think it’s implicit, proportionate to your contributions, then you can be held to account.” That legal clarity, she added, may prompt states to scale up their Loss and Damage fund contributions voluntarily, rather than risk being taken to court.

The court also affirmed that a healthy, sustainable planet is a precondition for human rights, putting climate responsibility at the heart of international law, as a duty to protect the conditions for life itself. That duty spans generations: We are trustees of humanity, charged with safeguarding dignity for those to come.

Prasad, the PISFCC campaign director, was “completely overjoyed” with the outcome: “This opinion is a lifeline and an opportunity to protect all that we hold dear and love. It is also a testament to the resolve of people everywhere, those at the front lines, who chose not to allow the decisions of a minority of countries to dictate the future of the global majority.”

The ICJ’s opinion is not legally binding, but it carries weight. By affirming that states have existing legal duties—not just voluntary climate pledges—and that failure to act may trigger legal responsibility, it arms activists and states with new leverage. By recognizing that harm may warrant reparation, the court moves Loss and Damage closer to justice, not charity. Vanuatu plans to bring the opinion back to the UNGA, seeking a resolution to support implementation.

In 1992, Vanuatu endured one of its most brutal cyclone seasons on record: Multiple storms tore through homes and crops, leaving communities reeling. That same year, Regenvanu illustrated The Story of the Eel, a tale from his clan’s island of Uripiv. In it, man is determined to catch an eel. He takes and takes—killing its children—until nothing is left. Ignoring his child’s warning, he and his friends feast on the eel. His house transforms into a cave, its entrance sealed shut. One by one, the men die inside. It’s a parable about taking too much, ignoring quiet warnings, and the costs of unchecked hunger.

In Vanuatu, such stories aren’t just myth—they are memory and instruction. “Our culture is built around the lessons we’ve learnt, the resilience we’ve built over thousands of years of living with a changing climate,” Regenvanu said. “It’s all about learning the lessons of your past, so you don’t repeat the same mistakes.”

This time the warning has been heard. The cave remains open. What happens next is up to us.