THE INTERNATIONAL COURT OF JUSTICE SHOWS THE WAY, BUT COP30 DOES NOT FOLLOW 

At COP30, Pacific leaders sound the alarm: the historic opinion of the ICJ has made climate inaction legally incompatible with climate obligations. Now there is only one challenge: will the Belém negotiations honor this legal truth, or will they work around it?

• After the historic ruling of the International Court of Justice in July 2025, failing to reduce emissions with due diligence constitutes a violation of International Law. However, some countries are attempting to hinder the implementation of the Advisory Opinion in various ways.
• The Advisory Opinion of the International Court becomes a leverage tool for vulnerable countries to demand binding commitments on climate finance, fossil fuel phase-out, and Loss and Damage.
• The 1.5°C goal has become a legal benchmark rather than an aspirational one: NDCs and national policies must be aligned, or they risk being considered unlawful acts.

This is the first COP in history to take place in the wake of a ruling by the International Court of Justice on climate justice. In July 2025, responding to the request of Vanuatu and the United Nations General Assembly, the Court in The Hague clearly and unequivocally established that the insufficient reduction of greenhouse gas emissions is not merely an irresponsible political choice: it is a violation of international law. 

At COP30 in Belém, while the latest Nationally Determined Contributions (NDCs) proved dramatically inadequate to keep warming within 1.5°C, the ICJ (International Court of Justice) Advisory Opinion (AO) is becoming the most powerful legal lever ever to enter a UNFCCC negotiating room.

Laiane Italia, Attorney General of Tuvalu, reaffirmed this forcefully during a dedicated press conference: ‘The Advisory Opinion represents an unprecedented leverage for this COP and for discussions on States’ legal obligations. Even though it is not binding, it has answered two crucial legal questions by declaring that States have binding obligations deriving from climate agreements. The duty of negotiators is now to incorporate its rulings and statements into the final texts.

Savendra Michael, Permanent Secretary of the Ministry of Environment and Climate Change of Fiji, pointed out the concrete applications: ‘The AO gives us the opportunity to maintain 1.5°C as an effective guiding rule, to secure stronger climate commitments in COP decisions, and to stay focused on a rapid and complete fossil fuel phase-out. Above all, it serves to make the most rigorous commitments operational, reaffirming the duty of cooperation set out in Articles 9.1 and 9.4 of the Paris Agreement: developed countries must provide the financial resources needed by developing countries for adaptation and response to irreversible impacts. We must focus on how to leverage the judges’ conclusions without undermining the hard work done to achieve them. Honestly, it is disappointing to see attempts to discredit the Advisory Opinion in these rooms.

Vishal Prasad, Director of Pacific Island Students Fighting Climate Change, framed the issue in terms of historical and political responsibility: ‘The question to ask in Belém is no longer whether States have obligations to act on climate: the Court has already answered that clearly. The only remaining question is whether the Parties will honor these obligations or openly choose to ignore them. At the opening of the Summit, the UN Secretary-General called the failure to keep 1.5°C within reach a moral failure of deadly negligence. The ICJ’s opinion tells us that it is not just a moral failure: it is also a legal failure”.

Pacific speakers also clarified that the AO is not a tool to be used in isolation: the strategy is to interpret it together with other recent international rulings, such as those of the International Tribunal for the Law of the Sea (ITLOS), the European Court of Human Rights, and the Inter-American Court of Human Rights, which converge in outlining a solid and coherent legal framework for States’ international obligations in the context of climate change. This approach, they explain, serves to strengthen the arguments of small island states and the most vulnerable countries, particularly in the face of attempts to challenge IPCC science, weaken the 1.5°C reference, or avoid classifying inaction and the misalignment of NDCs as violations of international law. It is a gradual process, they acknowledge, but already capable of significantly enhancing the negotiating position of countries most exposed to climate impacts, making it more difficult to ignore the legal obligations highlighted by the Court.

In the negotiating rooms, however, resistance is palpable. Some countries—‘the same ones that have been slowing progress for thirty years,’ Prasad emphasizes—are trying to obstruct the incorporation of the AO into decision texts in various ways:

• blocking explicit references to the ruling;
• challenging the 411 references to IPCC reports, which the Court calls four times “the best and most comprehensive science available” (data accepted by all Parties);
• attempting to dilute the 1.5°C target, non-negotiable for Pacific seats and all SIDS (Small Island Developing States), which the AO elevates to a primary temperature goal and a legal standard under the Paris Agreement for all national climate policies;
• avoiding any language that qualifies inaction or the misalignment of NDCs with the 1.5°C goal as internationally wrongful acts, with potential legal consequences and a solid basis for future litigation.

The Advisory Opinion thus becomes the benchmark for the battles of the second ministerial week, particularly on the new collective quantified climate finance goal (NCQG), closing the ambition gap, Loss and Damage, and the Global Stocktake.

On finance, the Court has been crystal clear: States with the greatest capacity and historical responsibility have a legal obligation to cooperate in addressing Loss and Damage and supporting adaptation. In the coming days, when numbers, deadlines, and funding sources are discussed, the question will no longer be what is politically convenient, but whether the final package respects the legal duty to support those most affected by the impacts of climate change.

On mitigation, intense debates are taking place over the speed and equity of the fossil fuel phase-out. Civil society, experts, and vulnerable delegations emphasize that a rapid, just, and financed phase-out is essential to close the ambition gap, especially here in the Amazon, where deforestation and oil expansion bring us closer to irreversible tipping points. The AO reinforces this concept: continuing to expand fossil fuels, knowing the harm they cause, is incompatible with States’ legal obligations.

Outside the negotiating rooms, this week tens of thousands of people—indigenous peoples, youth, scientists, and affected communities—are reminding everyone that climate change is, above all, a human rights crisis. In particular, the Court has strongly emphasized that States must pay special attention to those who are most vulnerable and least responsible.

This has been called the COP of truth; Pacific leaders have repeatedly reminded us. The International Court of Justice has already delivered the legal truths; now, for negotiators and Ministers leading the second week, there is only one question: will they let that truth guide the final text, or will they— as too often in the past—try to negotiate around it?

Article by Marta Abbà and Elisa Mauri, delegates of the Italian Climate Network.

Cover image: UN Climate Change photo – Zô Guimarães