The International Court of Justice will be beamed live globally when it reveals nations' obligations to prevent climate harm and redress damage caused by greenhouse emissions.
In a decision set to resonate around the world, International Court of Justice president Judge Iwasawa Yuji will deliver the "advisory opinion" at The Hague on Wednesday night (AEST).
Pacific Island nations have been hardest hit by climate change and the move to ask the world court to rule on the issue was initiated by Vanuatu University law students.
That eventually led to 132 nations co-sponsoring a request in 2023 for the world court to give a non-legally binding opinion on nations' responsibilities for climate change prevention and redress for emissions damage caused.
Small islands and low-lying developing countries' contribution to the problem has been far less than richer developed nations.
This injustice has climate-vulnerable states pushing hard for faster emissions cuts as well as compensation for the loss and damage they have done little to create.
The landmark case concludes ahead of the next round of international climate talks in November and the advisory opinion is expected to influence negotiations at the summit in Brazil.
Vanuatu's Minister for Climate Change Adaptation, Ralph Regenvanu, said he was "very hopeful" of a strong outcome.
"There's a readily identifiable group of states who are the main offenders," he told AAP.
"They're the ones who are going to bear the consequence of not fulfilling what, we hope, will be their legal duty to prevent climate harm."
Australia is bidding to co-host the 2026 climate event alongside Pacific nations.
University of Melbourne environmental law expert Jacqueline Peel said Australia in its court submission took a "fairly narrow view" of its international obligations, centred on those spelled out in the Paris climate agreement.
Professor Peel said the advantage of the Paris agreement for big-emitting countries was that emission reduction targets were set by the nations themselves, rather than being subject to a broader international standard.
Climate Change Minister Chris Bowen said in a statement the Albanese government had restored Australia's reputation as a constructive climate leader "particularly in the interest of our Pacific neighbours and other countries who are particularly vulnerable to climate impacts".
Vishal Prasad, director of Pacific Island Students Fighting Climate Change, said he hoped the court affirmed that climate inaction, especially by major emitters, was not merely a policy failure, but a breach of international law.
That would empower vulnerable nations to demand accountability, strengthen legal arguments and push for policies that "prioritise prevention and redress over delay and denial," he said in a statement.
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