A big week for climate litigation

Last week saw significant developments in climate litigation, both internationally and in Australia. In a decision that is expected to accelerate climate change litigation on a global scale and have wide sweeping impacts throughout parliaments, courts and boardrooms, the world's highest court, the International Court of Justice (ICJ), issued a landmark Advisory Opinion on the obligations of States with respect to climate change on 24 July 2025.

The ICJ Advisory Opinion is in stark contrast to the Federal Court of Australia's decision earlier this month that reaffirmed the Commonwealth Government did not owe a duty of care to people of the Torres Strait Islands to protect them from the impacts of climate change.

The New South Wales Court of Appeal also handed down a significant judgment overturning a 2022 approval for a large coal mine expansion on the basis that the consent authority had not considered all the likely environmental impacts of the Project on the locality because it had not expressly considered adverse climate impacts.

These cases underscore the growing role of courts in shaping climate accountability. The key points:

Global accountability for climate harm: The ICJ ruled that all nations, regardless of their participation in climate treaties, have a legal duty under international law to prevent significant harm to the climate system, regulate private emissions, and adopt science-based climate targets.

Localised environmental considerations: The NSW Court of Appeal invalidated a coal mine expansion approval due to the Independent Planning Commission's failure to consider the localised climate impacts of greenhouse gas emissions (including Scope 3 emissions) on the surrounding environment and community.

Evolving legal landscape: These cases reflect a growing trend of courts holding governments and private entities accountable for their contributions to climate change, both globally and domestically.

The ICJ's landmark Advisory Opinion

On 23 July 2025, the International Court of Justice (ICJ), the United Nation's principal judicial body, delivered its much anticipated Advisory Opinion on Obligations of States in respect of Climate Change.

The ICJ was asked to opine on:

• the obligations of States under international law to ensure the protection of the climate system and other parts of the environment from anthropogenic emissions of greenhouse gases;

• the legal consequences under these obligations for States where they, by their acts and omissions, have caused significant harm to the climate system and other parts of the environment, with respect to:

  • other States, including, in particular, small island developing States, which due to their geographical circumstances and level of development, are injured or specially affected by or are particularly vulnerable to the adverse effects of climate change; and

  • peoples and individuals of the present and future generations affected by the adverse effects of climate change.

The ICJ unanimously found that all States have binding legal obligations to protect the environment from greenhouse gas emissions and combat climate change. While the ICJ's decision is advisory and non-binding, it is based on an extensive review of international laws that States, including Australia, have committed to upholding.

State obligations

The ICJ endorsed the application of the entire body of international law and not just key climate treaties such as the United Nations Framework Convention of Climate Change (UNFCCC), the Kyoto Protocol and the Paris Agreement. Parties to these major climate change treaties, as well as other environmental and human rights treaties, have binding legal obligations to protect the environment, including addressing climate change.

Consequently, States that are not parties to, or have withdrawn from key climate treaties, have a duty to address climate change under customary international law, with the ICJ concluding that the duty to prevent significant harm to the environment and the duty to co-operate for the protection of the environment (a key tenet of environmental law) apply in the context of climate change. The ICJ also recognised the human right to a “clean, healthy and sustainable environment” as this is “inherent in the enjoyment of other human rights” and has now crystallised into customary international law. This was contrary to the argument of Australia, and other large carbon-emitting nations, at the ICJ hearing that nations' obligations largely did not extend beyond major international climate treaties (mainly, the Paris Agreement).

The ICJ found that States' obligations under the climate change treaties include adopting measures to reduce greenhouse gas emissions and to adapt to climate change and that all States are required to cooperate to achieve these objectives, including sharing financial resources, technology and information for capacity-building. The ICJ made clear that developed countries are obligated to take the lead, including supporting adaptation efforts in developing and vulnerable States.

With respect to Nationally Determined Contributions (NDCs) under the Paris Agreement, the ICJ said these constitute binding obligations of conduct for States and failure to draft and maintain these NDCs is considered an internationally wrongful act. Parties must ensure their NDCs represent their "highest possible ambition" and capable of limiting global warming to 1.5°C, which the ICJ acknowledged "has become the scientifically based consensus target under the Paris Agreement". This is significant for Australia with its updated NDC, which will include its 2035 target, due later this year (following advice from the Climate Change Authority) and the debate about whether Australia is meeting its current commitments under the Climate Change Act 2022 (Cth) and if they align with existing climate science.

Legal consequences

The ICJ held that breach of any of the obligations relating to climate change under international law constitutes an international wrongful act, for which the respective State is responsible and can face legal consequences, including:

• ceasing the harmful conduct;

• providing assurances and guarantees of non-repetition; and

• granting full reparation for any damage caused – in the form of restitution, compensation and satisfaction. Restitution may take the form of reconstructing damaged or destroyed infrastructure (for example, restoring ecosystems and biodiversity or repairing seawalls). In the event that restitution is materially impossible, responsible States then have an obligation to compensate.

According to the ICJ, any State can be held accountable for breaches of the climate change obligations identified in the Advisory Opinion, regardless of whether they have caused harm directly or indirectly and, because all States have a common interest in safeguarding the climate system, any State may invoke responsibility for such breach.

In considering attribution, the ICJ said a State is to be held responsible for its own conduct or failure to take appropriate action to protect the climate system from greenhouse gas emissions – including through fossil fuel production, fossil fuel consumption, the granting of fossil fuel exploration licences or the provision of fossil fuel subsidies. The ICJ held that the obligation extends to implementing regulatory and legislative measures to prevent private actors in their territory from causing significant climate harm.

The ICJ also rejected submissions that it is difficult to invoke responsibility in the context of climate change given that the wrongful conduct is cumulative in nature, involving different States over a period of time and involving a plurality of States that cause injury to a plurality of injured States. Importantly, the ICJ said it is scientifically possible to determine each State's total contribution to global emissions, taking into account both historical and current emissions.

In what could become a sad but future reality, the ICJ also found that Pacific island and other low lying nations, which ultimately lose their territory because of sea level rise, will still have a nationhood as territory (while needed to establish it) was not required to maintain it.

Potential implications

While not a binding decision, the Advisory Opinion has elevated climate protection to a matter of international law and human rights. With this clear declaration from the ICJ that States do have a legal obligation under international law to address climate change and may be held responsible, it is expected to influence ongoing and future climate litigation, as well as government decision making in relation to NDCs and the regulation of private entities in respect of greenhouse gas emissions, going forward. While it is envisaged that the Advisory Opinion will primarily be invoked in legal proceedings against federal and state governments, it could be used in broader climate and sustainability litigation against large corporations as claimants turn to international law principles to assess whether corporates have complied with their duties in relation to climate related impacts and risks.

The role of the Australian Government with respect to climate accountability

Pabai Pabai v Commonwealth of Australia

In the week prior to the Advisory Opinion being released, on 15 July, the Federal Court of Australia, in the case of Pabai Pabai v Commonwealth of Australia (No 2) [2025] FCA 796, found that the Commonwealth Government did not owe a duty of care to people of the Torres Strait Islands to protect them, their way of life, and the environment from the impacts of climate change.

In this case, two Torres Strait Islander leaders argued, on behalf of their communities, similar but alternative negligence claims, both hinging on the proposition that the Australian government owes a duty of care to take reasonable steps to prevent or mitigate the impacts of climate change (such as rising sea levels and coastal erosion).

• The first claim argued that the Commonwealth's greenhouse gas emissions reduction targets that were set and communicated to the UNFCCC in 2015, 2020, 2021 and 2022 were insufficient to meet the duty of care, as they failed to have regard to the best available science (primary duty argument).

• The alternative claim argued that the approach taken to funding and constructing seawalls on vulnerable islands was insufficient to meet the standard due to delayed, unpredictable and inadequate funding to complete the project (alternative duty argument).

Justice Wigney, following similar reasoning to the Full Federal Court in Minister for the Environment v Sharma [2022] FCAFC 35, ultimately held that the Commonwealth did not owe, and therefore did not breach, a duty of care to Torres Strait Islanders to take reasonable steps to prevent or mitigate climate change. The Applicants, distinguishing from Sharma, argued that Torres Strait Islanders are a small, discrete and unique group of Indigenous Australians who are particularly vulnerable to the effects of climate change (Sharma considered a duty of care owed to all Australian children). While Justice Wigney accepted this distinction, his Honour held that the Commonwealth did not have a special protective relationship with Torres Strait Islanders that might give rise to a novel duty of care.

While the Federal Court made relevant findings about whether particular emissions targets were compatible with the "best available science", the Court could not judge whether it was unreasonable for the Commonwealth to set emissions reduction targets by reference to other considerations, such as broader economic, social, and political factors. The Court found that the answer to that question involves value judgments, policy choices, and political judgments, which are matters to be determined by the government, not the courts. Furthermore, even if a duty of care existed and was breached, the Applicants could not prove that this breach materially contributed to their loss, given the global nature of climate change (i.e. there was a lack of causation).

It was considered that this decision, along with the earlier Sharma decision, presented a significant obstacle for future novel climate change duty of care cases in Australia. Many aspects of this decision are contrary to what the ICJ has now advised, particularly with respect to setting targets that represent a country's "highest possible ambition" and are capable of limiting global warming to 1.5°C and with respect to climate impact attribution.

Mount Pleasant coal mine expansion

Lastly, the NSW Court of Appeal determined that a large coal mine expansion approval granted in 2022 was invalid the day after the ICJ Advisory Opinion was delivered. In Denman Aberdeen Muswellbrook Scone Healthy Environment Group Inc v MACH Energy Australia Pty Ltd [2025] NSWCA 163, the Court of Appeal determined that the Independent Planning Commission had failed to take into account a mandatory consideration in assessing the impacts of the mine expansion, specifically, the likely climate impacts associated with all greenhouse gas emissions (including scope 3 emissions) generated from the mine expansion on the surrounding natural and built environment.

The Court of Appeal ordered the matter be remitted to the Land and Environment Court to reconsider and determine whether or not further orders can or should be made, which if complied with, will validate the development consent.