What is the Vanuatu ICJ initiative?

What is an advisory opinion? 

An advisory opinion is a legal clarification provided on points and questions of law to the UN or a specialised agency by the ICJ, in accordance with Article 96 of the UN Charter.

What advisory opinion did Vanuatu ask the ICJ for? 

In March 2023, the UN General Assembly voted to ask the ICJ to clarify the obligations of States in relation to climate change, and the legal consequences if those obligations are not complied with. Put simply, States wanted to know what international law has to say about what States are required to do about climate change. 

The core group of States, i.e. Vanuatu, Antigua and Barbuda, Costa Rica, Sierra Leone, Angola, Germany, Mozambique, Liechtenstein, Samoa, Federated States of Micronesia, Bangladesh, Morocco, Singapore, Uganda, New Zealand, Vietnam, Romania and Portugal lead the drafting of the questions to the ICJ. 

What did the ICJ decide?

On Wednesday 23rd July 2025, the ICJ issued its advisory opinion in response to the request from Vanuatu and other states.

In a historic decision, the Court unanimously confirmed that big polluters must scale up their efforts to address climate change under international law.

It also said:

• If governments and parliaments fail to curb the production and consumption of fossil fuels, approve fossil fuel projects and roll out public money for fossil fuels, they could be in breach of international law.
• Historical emitters (i.e. countries who have burned the most fossil fuels for the longest periods of time) have a greater responsibility to address the climate crisis and limit global warming to 1.5 C.  
• Countries are bound by international law to regulate companies and businesses’ climate impacts.  
• A healthy environment is the foundation for human life and human rights protected by international law.  
• There is a potential route to reparations for states enduring the worst of the climate crisis to hold historical emitters to account.

ClientEarth lawyer Lea Main-Klingst said: 

“Today’s decision is a once-in-a-generation moment for all of us fighting for climate justice.  

“The world’s highest court has affirmed what millions of people all over the world have said time and time again: climate change threatens our very survival - and high-emitting states can and must be held accountable for the damage they’ve done.  

“The judges have also sent a clear message to corporate and financial giants: the age of producing and bankrolling fossil fuels with abandon is over.”  

Why was this action taken? 

The scientific evidence is clear on how the climate crisis is already harming (and will continue to harm) human life and well-being. In early 2023 for example, Vanuatu faced two category four cyclones within 72 hours – unprecedented in history. States have duties under different international laws, like human rights law and the Law of the Sea, to reduce climate harms, and there are legal consequences for failing to do so. 

It was the first time that the ICJ – the UN’s highest judicial organ, was given the opportunity to address the climate crisis. 

How did it work? 

Ahead of the hearings, all member States of the United Nations, as well as authorised intergovernmental organisations were able to provide written submissions to the Court. The first round of written submissions was due on 22 March 2024. On 15 August 2024, a second round of submissions was due.

In December 2024, the hearings for the advisory opinion took place in The Hague. An unprecedented number of States and intergovernmental organisations appeared before the court and judges heard directly from countries and communities that have been at the frontlines of the climate crisis for decades.

In July 2025, the ICJ delivered its opinion.

What does this positive advisory opinion mean for climate law? 

The new-found clarity of this decision gives judges definitive guidance that will likely shape climate cases for decades to come. 

The result is also a powerful advocacy tool. Each and every one of us can use this decision to demand our governments and parliaments take more ambitious action on climate change to comply with both the Paris Agreement and other applicable international laws.  

People everywhere to pick up this new tool and use it, including at major climate negotiations like COP.

Closer to home – with the wind of this decision behind them, national governments and parliaments have an even greater responsibility to implement strong, ambitious plans to avert the worst of the climate crisis and protect our human rights.

How was ClientEarth involved? 

NGOs and civil society organisations aren’t able to provide formal submissions to the ICJ. But we published a legal briefing on the questions before the court here. 

In July 2024, ClientEarth, CIEL, Pacific Islands Students Fighting Climate Change and World’s Youth for Climate Justice published a joint legal memorandum on the relevance of the ITLOS advisory opinion for the advisory opinion proceedings before the International Court of Justice. The full memo can be found here.