Statement from the UN’s highest court is a turning point in the climate fight. It could become a global shift in moral authority.

In a historic ruling, the International Court of Justice (ICJ) has issued its long-awaited advisory opinion on climate change – and it is nothing short of a game-changer. For the first time, the world’s highest court has clearly defined that climate inaction is not just irresponsible – it may be unlawful.

It took two hours to read aloud the Court’s legal opinion. Judge Yuji Iwasawa, President of the ICJ in The Hague on 23 July 2025, delivered a meticulous and comprehensive statement, reviewing decades of climate treaties, legal conventions and binding principles of international law.

The conclusion was crystal clear:

All states are, beyond any legal doubt, obliged to protect the climate from harmful human-caused changes. This duty exists not only under climate treaties like the UNFCCC, Kyoto Protocol and Paris Agreement, but also under customary international law, international human rights law and the law of the sea.

The implications for Australia are profound – and immediate.

Legal obligations beyond treaties

The ICJ found that even if a country withdraws from climate treaties, its responsibility to reduce greenhouse gas emissions does not disappear. Under international law, states remain bound by longstanding legal principles that prohibit causing transboundary harm and require good-faith cooperation.

This overturns the old framing of climate action as voluntary or aspirational. Under this new legal interpretation, Australia remains liable, regardless of its domestic policies or treaty commitments.

1.5°C is now the legal threshold

One of the most powerful outcomes of the opinion is the Court’s confirmation that the 1.5°C global warming limit is a legally binding target under international law.

This means that Australia must align all new projects and national plans – including coal mines, gas fields, fracking developments and energy infrastructure – with a pathway that stays within the 1.5°C boundary. Projects like Scarborough and Beetaloo, and policies that support continued fossil fuel expansion, are now under serious legal scrutiny.

Reparations for climate harm

Australia may also face liability for damage caused to other nations, particularly vulnerable Pacific island states. This could involve reparations such as:

• Restoring damaged ecosystems
• Rebuilding destroyed infrastructure
• Providing financial compensation or formal acknowledgement of harm

These forms of restitution, compensation and satisfaction are recognised mechanisms under international law, and they may now apply to climate impacts.

Fossil fuels in the spotlight

For the first time, the Court has stated that failure to address fossil fuel production, consumption, and subsidies may constitute violations of international law. This casts a legal spotlight on Australia’s more than $11 billion in annual fossil fuel subsidies, as well as ongoing approval of coal and gas projects.

Governments and companies engaged in expanding fossil fuel infrastructure could now face legal challenges for breaching their international obligations.

Sovereignty of Pacific nations affirmed

The ICJ also ruled that island nations permanently inundated by sea level rise will retain their statehood and maritime boundaries, even if their populations must relocate. This is a monumental win for countries like Tuvalu and Kiribati, and a clear message that climate-related loss of territory does not erase national sovereignty.

For Australia, this reinforces a moral and legal responsibility to act in solidarity with our neighbours – not to contribute to the very crisis that threatens their existence.

Climate displacement is a legal matter

The Court affirmed that people displaced by climate impacts are protected under the principle of non-refoulement, which prohibits returning individuals to life-threatening conditions. This principle, usually applied in refugee law, now extends to those displaced by the climate crisis.

Australia must therefore consider new obligations, including:

• Accepting Pacific climate refugees
• Avoiding deportation to climate-ravaged regions
• Rethinking immigration and border policy in the climate era

Legal challenges will follow

The ICJ’s ruling will almost certainly encourage further legal actions, including lawsuits by Pacific states, First Nations peoples, young Australians and environmental defenders. Cases like Sharma v Minister for the Environment, previously dismissed or narrowly interpreted, may now be revisited with renewed force.

The precedent is now set: governments and corporations that fail to meet international climate obligations can be held accountable in court.

A global shift in moral authority

Beyond the legal ramifications, the Court’s opinion sends a powerful moral message. Climate justice is not just a political cause. It is now rooted in international law.

Inaction or continued fossil fuel expansion is not merely poor governance. It could now be grounds for legal action.

As Barrister Harj Narulla – who represented Solomon Islands at the ICJ – observed:
“For the ICJ, this decision is truly radical.”

The Court rejected the argument that only climate treaties matter. It confirmed that major emitters such as the US, China, India – and yes, Australia – have clear obligations under law. All members of the United Nations are party to the ICJ.

Fossil fuel industries have been formally put on notice. Inundated island nations retain their rights. Displaced people gain legal protection.

This is a seismic shift in global climate governance. The ICJ has laid the groundwork for a new era of accountability – and Australia, like every other nation, must now answer to it.

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Full ICJ opinion available here:
www.icj-cij.org/sites/default/files/case-related/187/187-20250723-adv-01-00-en.pdf

EXCERPT OF THE STATEMENT

“The duty of states to prevent significant environmental harm applies in the context of climate change, and this duty forms part of the most directly relevant applicable law. Concerning the duty to cooperate, the Court recalls that it lies at the core of the Charter of the United Nations and has been spelled out in the foundational Declaration on Friendly Relations.

The Court has held that the adoption by states of this text affords an indication of their opinio juris as to customary international law. That observation also applies to the duty to cooperate, in so far as it finds expression in many binding and non-binding instruments relating specifically to the environment.

The duty to cooperate is a central obligation under the climate change treaties and other environmental treaties. In view of the related practice of states, the Court considers that the duty of states to cooperate for the protection of the environment is a rule whose customary character has been established.

The Court considers that a clean, healthy and sustainable environment is a precondition for the enjoyment of many human rights, such as the right to life, the right to health, and the right to an adequate standard of living, including access to water, food, and housing.

The right to a clean, healthy and sustainable environment results from the interdependence between human rights and the protection of the environment. Consequently, in so far as state parties to human rights treaties are required to guarantee the effective enjoyment of such rights, it is difficult to see how these obligations can be fulfilled without at the same time ensuring the protection of the right to a clean, healthy and sustainable environment as a human right.

The human right to a clean, healthy, and sustainable environment is therefore inherent in the enjoyment of other human rights. The Court thus concludes that under international law, the human right to a clean, healthy and sustainable environment is essential for the enjoyment of other human rights.”

QUOTES

“For young people, and for future generations, this opinion is a lifeline.”
~ Vishal Prasad, Director, PISFCC

“Today, Australia has found itself on the wrong side of history.”
~ Harj Narulla, barrister and leading global expert on climate litigation at Doughty Street Chambers and the University of Oxford.

MEDIA COVERAGE

AUSTRALIA RELATED

→ Climate & Capital Media – 25 July 2025:
Top UN court declares climate inaction illegal
“Countries failing to address climate change could be ordered to pay reparations – International Court of Justice”

→ The Guardian Australia – 24 July 2025:
The ICJ’s ruling means Australia and other major polluters face a new era of climate reparations
“Countries are now bound under international law to reduce emissions or pay damages to affected nations – a clear statement that the status quo is not sufficient.”

→ The Guardian – 24 July 2025:
Australia warned it could face legal action over ‘wrongful’ fossil fuel actions after landmark climate ruling from world’s top court
“Vanuatu climate change minister says ICJ opinion gives Pacific island nations ‘much greater leverage’ in dealing with partners such as Australia.”

→ AAP – 24 July 2025:
Australia may be target of legal action on climate
“Australia could become the subject of legal action after an international court said countries have an obligation to prevent climate change harm and redress damage caused by greenhouse gas emissions. It opens the way for countries to potentially sue each other over climate change impacts.”
Also on Yahoo News

→ 9News – 24 July 2025:
What ‘historic’ UN court climate ruling means for Australia and the world
“A “historic” court ruling could pave the way for reparations for nations harmed by climate change and force major fossil fuel exporters such as Australia to look hard at taking greater action.”

→ The Conversation – 24 July 2025:
World’s highest court issues groundbreaking ruling for climate action. Here’s what it means for Australia
“The world’s highest court says countries are legally obliged to prevent harms caused by climate change, in a ruling that repudiates Australia’s claims it is not legally responsible for emissions from our fossil fuel exports.”

→ ABC News – 24 July 2024:
International Court of Justice says countries failing to tackle climate change risk breaking international law
“Countries that do not act to prevent climate change could be breaching international law, the United Nations’s top court has declared. The International Court of Justice has also advised that other states impacted by climate change could be entitled to reparations. Experts are still analysing the court’s advisory opinion, which is more than 500 pages long.”

→ Climate Council – 24 July 2025:
World’s highest court’s landmark decision carries major implications for Australia’s climate obligations
“A historic and unanimous ruling of the International Court of Justice has confirmed countries’ strong obligations under international law to slash climate pollution, and set out the expected legal consequences for breaching these obligations.”

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→ The Guardian – 25 July 2025:
‘We were heard’: the Pacific students who took their climate fight to the ICJ – and won
“In a packed court thousands of kilometres from home, Cynthia Houniuhi saw years of work come to fruition with the landmark ICJ opinion on climate harm.”

→ The Conversation – 24 July 2025:
Historic ruling finds climate change ‘imperils all forms of life’ and puts laggard nations on notice
“Here’s what the court ruled – and the global ramifications likely to flow from it.”

→ Reuters – 24 July 2025:
Top UN court says treaties compel wealthy nations to curb global warming
“ICJ opinion could influence global climate litigation. U.N. treaties should guide responsibilities, rich countries say. South, small island states seek firm measures to curb emissions.”

→ Climate Action – 24 July 2025:
International Court of Justice Issues Landmark Climate Ruling
“In an historic moment for international climate law, the International Court of Justice (ICJ) has issued a sweeping advisory opinion confirming that states have binding legal obligations to prevent environmental harm caused by climate change, including from fossil fuel production and subsidies.”

→ Stop Ecocide – 23 July 2025:
International Court of Justice Sets Out States’ Climate Obligations – Major Implications for Ecocide Law
“In a landmark advisory opinion, the International Court of Justice (ICJ) has clarified that states have binding legal obligations under international law not only to protect the climate system and the environment, but also to prevent harm, cooperate across borders, and provide reparations where damage occurs.”

→ The Guardian – 23 July 2024:
Top UN court singles out fossil fuels as part of states’ climate duty
“Landmark opinion says those that fail to prevent climate harm could be liable for compensation and restitution.”

PODCASTS

→ The New Daily podcast – 28 July 2025:
The students behind the historic international climate ruling

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→ Climate Roulette Podcast – 24 July 2025:
The ICJ’s Brand New Climate Ruling

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REACTIONS

I welcome that the @CIJ_ICJ has just made it very clear: all States are obligated under international law to protect the global climate system.

This is victory for planet, for climate justice, and for the power of young people leading the way.https://t.co/iZoKfw4tLR pic.twitter.com/JkC67t79fO

— António Guterres (@antonioguterres) July 23, 2025

A Victory for Climate Justice:
AOSIS Welcomes Landmark ICJ Ruling

The Alliance of Small Island States (AOSIS) welcomes today’s historic Advisory Opinion from the International Court of Justice (ICJ) — a global affirmation that climate harm is not just unjust, it is unlawful.

This ruling is a testament to what small states can achieve through principled diplomacy, collective advocacy, and legal innovation. In 2019, 27 Pacific law students at the University of the South Pacific in Vanuatu planted the seed of an idea: that the world’s highest court could help protect the rights of nations most exposed to the climate crisis. That idea became a movement — led by youth, championed by Vanuatu, and supported by civil society, legal experts, and the solidarity of Small Island Developing States (SIDS).

In 2023, over 130 countries co-sponsored a UN General Assembly resolution calling on the ICJ to clarify States’ legal duties on climate change. Today, that initiative comes full circle — delivering a ruling that recognizes and reinforces key principles that AOSIS and our members have long upheld.

“This opinion reflects the strength of collective advocacy and the hope that has driven this initiative from the very beginning. It is the result of sustained advocacy by Pacific youth, legal experts from vulnerable nations, and States that chose not to remain silent. The ICJ’s findings demonstrate that moral clarity and legal authority can reinforce one another. This ruling must serve as a foundation — not a conclusion. We now call on all States to act with renewed urgency and ambition, in accordance with their legal obligations and the demands of justice.”
~ Ambassador Ilana Victorya Seid, Chair of AOSIS and Permanent Representative of Palau to the United Nations

Key legal findings welcomed by AOSIS

• A binding 1.5°C obligation:
  The Court affirmed that the 1.5°C target is not merely a political aspiration — it is a legally binding obligation, based on the Paris Agreement and subsequent decisions of its governing bodies. This is a revolutionary development. For SIDS, holding the line at 1.5°C is essential for continued viability.
• The duty to cooperate:
  The Court reaffirmed that States have a customary legal obligation to cooperate in addressing climate change. Voluntary action is not enough. Climate justice demands coordinated, sustained, and legally mandated cooperation across borders.
• Maritime rights and sea-level rise:
  AOSIS strongly supports the Court’s affirmation that sea-level rise cannot invalidate existing maritime baselines and entitlements. This provides long-awaited legal certainty to island nations whose territorial integrity is threatened by rising seas.
• Continuity of statehood:
  The Court’s opinion upholds the principle that States do not lose their legal identity or rights due to climate-induced territorial loss. This aligns with AOSIS’s long-standing position that sovereignty endures — and must be preserved — even amidst profound physical changes.

Submission of NDCs representing parties’ highest possible ambition AOSIS has continuously called for the submission of enhanced, highly ambitious NDCs by September 2025, and the AO delineates that “each party must do its utmost to ensure that the NDCS it puts forward represents its highest possible ambition in order to realize the objectives of the agreement”. Furthermore, we welcome the decision that the standard of NDCs assessment will vary depending on historical GHG emissions, and level of development and national circumstances.

A new chapter in international law
Small Island Developing States are often called the moral voice of the climate movement. Today, we have demonstrated that our role is also legal, strategic, and enduring. The international legal system can be complex — but SIDS have shown how to navigate it with vision, determination, and skill.

This opinion is not the end of the road. It must now inform action across every level — including negotiations under the UNFCCC and Paris Agreement, implementation of national climate policies, and interpretation of rights and obligations in courts around the world.

In an increasingly unstable world, international law offers what SIDS need most: certainty, predictability, and resilience. We will carry this ruling into every negotiation, every courtroom, and every call for justice. For small islands, this is not just about climate — it is about our future. And we will never stop defending it.

About AOSIS: Since 1990, The Alliance of Small Island States has represented the interests of the 39 small island and low-lying coastal developing states in international negotiations on climate change, sustainable development, and oceans. As a voice for the vulnerable, AOSIS is key to ensuring the United Nations mandate to “leave no one behind” is honoured. On the global stage AOSIS often punches far above its weight, negotiating historic global commitments to cut greenhouse gas emissions, among other achievements.

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• Pacific Islands Climate Action Network’s reaction: Climate justice gets legal backbone as ICJ clarifies States’ duties on climate and human rights 

• Fossil Fuel Non-Proliferation Treaty Initiative’s press release includes some strong remarks from Vanuatu’s Climate Minister Ralph Regenvanu that connects the dots between Vanuatu’s efforts at ICJ, ITLOS, IACHR and the push for a Fossil Fuel Treaty. 

• Amnesty International, Global Climate & Health Alliance, CIEL, Oil Change International, ActionAid 

• For legal analsysis thought Harj Narulla’s legal analysis of relevant paragraphs and Seb Duyck’s live thread were both very helpful.

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Event today
There is a 90-minute rapid-reaction event A Verdict for the Planet: Legal and Political Reflections on the ICJ Climate Ruling webinar today that you may want to join. Details here.

“Following the historic delivery of the ICJ AO on climate change on 23rd July 2025, this seminar will provide a stage for leading experts from government, the legal fraternity, and the youth to reflect on the ICJ’s Advisory Opinion on climate change. This 90-minute rapid-reaction event offers top-line legal and political analysis, framing the opinion’s implications to bolster stronger climate action from a climate justice perspective.”

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“The ICJ says any breach of its obligations means the country could be liable to pay “full reparation to injured States in the form of restitution, compensation and satisfaction”. This is what Australia is risking by pushing ahead with inadequate policies, weak targets and more fossil fuels.”
~ Bill Hare on Linkedin – 24 July 2025
What does the ICJ climate finding mean for Australia and 1.5˚C?

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AUSTRALIA, HOW ARE WE DOING?

Two current Australian court cases Excerpt from ‘Insight’, the Environmental Defenders Office monthly newsletter:

Winchester South Coal Mine hearing starts this week This is the first week of an eight-week hearing before the Land Court of Queensland, and the EDO legal team are arguing our clients’ objections to the largest proposed new coal mine in Australia – Whitehaven’s Winchester South Coal Mine. Environmental Defenders Office are acting for Mackay Conservation Group and the Australian Conservation Foundation in this monumental case. Our outstanding team of lawyers has been working with counsel on this case for more than a year, with multiple court appearances and interlocutory steps. Only weeks ago, we secured a win for our clients, with the court dismissing Whitehaven’s motion to block a climate expert from providing evidence to the court, Whitehaven claiming it would ‘cause chaos’. The court can now hear this expert evidence. If the Winchester South Coal Mine goes ahead, every year for 28 years, 17 million tonnes of coal will be dug up and processed for export, eventually resulting in up to a staggering 583 million tonnes (CO2-e) of carbon pollution over its lifetime. This case is centred on the devastating impacts of climate change in Queensland, with evidence from leading experts on the harm already experienced by Queensland’s people and precious wildlife from climate driven disasters. → Read more

Court challenge against Woodside gas approval heard last week Last week, Environmental Defenders Office’s lawyers were in the Federal Court for the hearing of their client Doctors for the Environment Australia’s critical legal challenge to the final approval for Woodside’s Scarborough Gas Project. This project, located off the coast of Western Australia, will result in the release of an estimated 878 million tonnes of carbon dioxide equivalent, adding to the immense health burden that climate change is already putting on the community. In February, the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) accepted Woodside’s environment plan (EP), the last approval required before work could start. Doctors for the Environment Australia, the leading medical voice on health and climate in Australia, believes NOPSEMA acted unlawfully by accepting Woodside’s EP without fully understanding how the climate impacts of the project would be managed. Doctors for the Environment Australia sought judicial review of the project’s EP approval to ensure regulators and proponents abide by laws that aim to mitigate environmental impacts and harm to communities. → Read more

Courts around the world just delivered a legal reckoning on climate. Is Australia ready?

Newsletter from Project Planet – July 2025

For decades, communities on the frontlines of the climate crisis have demanded action — and accountability. Now, the world’s courts are starting to listen. Within three weeks, three historic climate rulings were handed down — from the Americas, The Hague, and here on home soil — each building the case that governments can no longer ignore the climate crisis without consequence. 

Together, they mark the beginning of a new era: where climate inaction isn’t just immoral or unjust. It’s unlawful. As international courts clarify what climate justice looks like, Australia is under growing pressure to align its laws — and its actions — with the direction of global legal momentum.

But before we get to that, let’s recap the cases…

Inter-American Court: Climate action is a human rights obligation

On July 3, the Inter-American Court of Human Rights issued a landmark advisory opinion declaring that states have clear legal duties to act on climate change — grounded in international human rights law.

The Court didn’t mince words: climate change violates fundamental rights, especially for Indigenous Peoples, Afro-descendant communities, women, children, and other groups who face disproportionate harm. It clarified that climate action is a human rights obligation — not a political choice.

Requested by Chile and Colombia, and informed by unprecedented civil society participation, the ruling creates powerful legal precedent across the Americas and beyond. It affirms that climate action isn’t optional. It’s a legal requirement.

International Court of Justice: States must act — or face legal consequences

On July 23, the world’s highest court — the International Court of Justice (ICJ) — handed down its much-anticipated opinion on states’ obligations in relation to climate change. Requested by the UN General Assembly after a youth-led campaign and advocacy spearheaded by Vanuatu and other Pacific nations, the ruling makes one thing clear: states have legal duties to prevent climate harm, grounded in environmental law, human rights law, and existing treaty obligations.

And if they don’t? They are in breach of international law.

In a unanimous ruling, all 15 judges reaffirmed that governments cannot continue business as usual. They addressed — for the first time at this level — the legal obligation to phase out fossil fuels, regulate corporate emissions, and provide reparations for climate damage.

The ICJ opinion isn’t legally binding in the way a court order is, but its legal authority is undeniable. It now sits alongside the Inter-American ruling — and last year’s opinion from the International Tribunal for the Law of the Sea — as part of a growing body of international jurisprudence that demands climate justice.

Australia: The court sees the harm — but the law hasn’t caught up

Just days before the ICJ ruling, on July 15, the Federal Court of Australia handed down its decision in a landmark case brought by Uncle Pabai and Uncle Paul, two Guda Maluyligal men from the Torres Strait.

They argued that the Australian Government’s weak climate targets and failure to implement effective climate adaptation measures amount to a breach of duty of care — one that puts their homes, culture and lives at risk.

The Court acknowledged the devastating impacts already being felt in the Torres Strait. Justice Wigney found that the region is being “ravaged by human-induced climate change” and that climate change poses “an existential threat to the whole of humanity.”

And yet, the case was dismissed.

The Court ruled that, under the law as it stands, the Commonwealth does not owe a legal duty of care to Torres Strait Islander Peoples. Compensation for cultural loss — Ailan Kastom — was also denied.

“That is not a closed door,” said Isabelle Reinecke of the Grata Fund, which supported the case. “It is an invitation to keep pushing the law.”

Despite the outcome, the case made history. It exposed that Australia’s climate targets prior to 2022 were set without regard to the best available science. It built a movement across the country and region. It demonstrated what the courts now accept as fact: that climate change is real, harmful, and accelerating.

And critically, the global legal context has now shifted. As Dr Wesley Morgan from the UNSW Institute for Climate Risk and Response noted, the ICJ advisory opinion could have a role to play if there were to be an appeal.

So, what do these rulings mean when considered together?

Together, these three decisions paint a clear picture of where international law is headed.

• The climate crisis is a human rights crisis — and courts are treating it that way.
• Governments must act — or face legal consequences under international law.
• There are no more excuses — fossil fuel phase-out is now a legal expectation.
• The courts are ready. The law is evolving. Justice is coming.

While the ICJ and Inter-American rulings aren’t binding, they create a powerful legal and moral context that makes further inaction politically, reputationally, and eventually legally untenable. They also provide a crucial foundation for appeals, future litigation, and stronger domestic legislation.

And what are the implications for Australia?

Well, the Australian Government is now at a crossroads.

On the home front, Uncle Pabai and Uncle Paul could appeal their case. As Reinecke puts it: “The walls are closing in on polluting states like Australia. Our government must either align policy settings with the direction the law is heading — or it will be forced to do so by the court.”

On the international front, Australia is expected to submit its updated Nationally Determined Contribution (NDC) under the Paris Agreement by September. With the global legal consensus shifting, the pressure is on to lift our ambition — and align our targets with climate science, not political convenience.

The pressure is mounting — in the courts, in communities, and across global institutions. This is no longer just about climate diplomacy or economic transition. It’s about justice. It’s about survival. It’s about the law.

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→ RenewEconomy – 30 July 2025:
Australia ranks third in world for new coal mines, despite climate commitments, report says
“Australia ranks third in the world after China and India for the amount of new coal mines under development”

Australia ranks third in world for new coal mines, despite climate commitments, report says

→ The Guardian – 21 July 2025:
‘Significant gap’ between Australian companies’ climate commitments and how they actually invest, analysts find
“Experts say the level of ambition in Labor’s upcoming 2035 emissions target will influence the capital decisions of many companies.”

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