Adopted Without a Vote
A campaign begun in 2019 by law students on a campus in Port Vila ended six years later with the International Court of Justice ruling unanimously on what states owe one another over climate change. Vanuatu — fewer than 350,000 people, and reliably near the top of every list of the world's most disaster-exposed countries — is the government that put the question there.
The School of Law of the University of the South Pacific occupies the Emalus campus at the western end of Port Vila, on a hill above the harbour. The university is owned jointly by twelve Pacific countries, and the law school is the only one of its kind in the region, which means most of the lawyers in a dozen small island states have sat in the same rooms. In 2019 a group of students there formed an organisation called Pacific Islands Students Fighting Climate Change, with a single objective: to persuade a government to ask the International Court of Justice what international law actually requires of states on climate change.
Governments do not usually take instruction from student societies. This one did. Vanuatu announced in September 2021 that it would pursue the idea, spent eighteen months building a coalition, and on 29 March 2023 the United Nations General Assembly adopted resolution 77/276 without a vote. On 23 July 2025 the Court delivered its opinion, unanimously, in the largest set of proceedings it has ever held.
Why it was Vanuatu
The country sits on the Pacific Ring of Fire, across the cyclone belt, on a subduction zone, with a coastline that is almost entirely populated. It held first place in the WorldRiskIndex in every edition from the index's first in 2011 until the methodology was rebuilt in 2022 and the ranking tilted towards countries with large exposed populations, which handed the top place to the Philippines and says more about the arithmetic than about Vanuatu. Cyclone Pam crossed the archipelago in March 2015 as a Category 5 storm and the post-disaster assessment put the damage at around 64 per cent of GDP — a figure that, applied to a large economy, would describe an event without modern precedent. In March 2023, four weeks before the General Assembly vote, cyclones Judy and Kevin arrived within forty-eight hours of each other and both reached Category 4. In December 2024 a magnitude 7.3 earthquake condemned buildings in the centre of the capital. The delegation that argued this case was, for a good deal of the time, arguing from a country in a state of emergency.
How the question was written
The wording mattered more than the venue. The resolution asked two things: what obligations states have under international law to protect the climate system for present and future generations, and what the legal consequences are where states have caused significant harm to it, both for other states and for peoples and individuals. Neither question named a defendant. Neither asked the Court to award anything. They were drafted to be answerable — and, just as deliberately, to be difficult to oppose in public. More than 130 states co-sponsored the text, no delegation called for a vote, and it passed by consensus, which is a procedural detail with real weight: no government is on record having voted against putting the question.
An advisory opinion cannot make anyone do anything. What it can do is establish what the law already required, which changes every argument that follows it.
The Hague, and what the Court decided
The oral hearings ran for two weeks at the Peace Palace in December 2024. Ninety-six states and eleven international organisations addressed the Court, more participants than in any proceedings in its history, and Vanuatu opened. The submissions split along a line that had been visible from the start. One group argued that the climate treaties — the Framework Convention, Kyoto, Paris — are a self-contained regime, that they set procedural obligations rather than results, and that nothing outside them applies. The other argued that those treaties sit within general international law and do not displace it: the law of the sea, human rights law, the customary duty not to cause significant transboundary harm. Almost everything else in the case turned on which of those two readings the Court adopted.
It adopted the second, unanimously. Obligations arise from the climate treaties and also from customary international law, the UN Convention on the Law of the Sea and international human rights law; the treaties are not a special regime that excludes the rest. The 1.5°C figure is the agreed benchmark against which conduct is measured, not an aspiration. Nationally determined contributions must represent a state's highest possible ambition and can be assessed objectively rather than taken on trust. Where a state breaches these obligations, it commits an internationally wrongful act, with the ordinary consequences — cessation, guarantees of non-repetition, and full reparation where a causal link can be established. The Court went further than most observers expected on one point in particular: it held that producing and consuming fossil fuels, granting exploration licences and providing fossil fuel subsidies may themselves constitute internationally wrongful acts, depending on the circumstances.
What an advisory opinion is not
It is not binding. The Court has no enforcement power here, no party has been ordered to pay anything, and nothing in the opinion obliges a single government to change a single policy. Anyone describing 23 July 2025 as the day the law changed is overstating it, and Vanuatu's own lawyers have been careful not to. What an opinion of this kind does is settle contested questions of law with the authority of the principal judicial organ of the United Nations, and that settlement is then available to everyone else — to domestic courts hearing climate cases against their own governments, to negotiators at the annual conferences, to states considering contentious proceedings against other states. The material is now on the shelf. Whether anybody takes it down is a separate question, and it will be answered over years rather than months.
From Port Vila
The case was not an isolated manoeuvre. In September 2022 Vanuatu became the first state to call from the General Assembly podium for a Fossil Fuel Non-Proliferation Treaty, borrowing the architecture of nuclear arms control for coal, oil and gas; in September 2024 it joined Fiji and Samoa in formally proposing that ecocide be added to the Rome Statute. The strategy is consistent and it is the only one available, because a country of this size has no leverage in markets and none in security, and works instead in the one arena where a vote counts the same regardless of who casts it. None of it is visible on the ground. The Emalus campus is a set of low buildings under casuarina trees, the centre of Port Vila is still repairing what the earthquake did to it, and the copra boats still load at the wharf. The Hague is sixteen thousand kilometres away and the opinion has changed nothing about the cyclone season. But a state with no material means of affecting global emissions spent six years converting a student campaign into a unanimous finding of law about what everyone else is required to do — from a country where the argument is not theoretical, because the thing being argued about arrives most summers and takes the roofs off.