Australia’s High Court Invalidates Coal Mine Expansion On Climate Grounds
Australia’s top court has handed down a landmark ruling in favor of a community group challenging the approval of a coal mine expansion in New South Wales, finding that the approval failed to adequately scrutinize the greenhouse gas emissions from the extracted coal that is burned overseas. The ruling in the first climate case to come before the High Court sets an important precedent with implications applicable to other fossil fuel projects in Australia, and its significance could even extend globally, legal experts say.
In a 3-2 decision issued on October 7, Australia’s High Court determined that a planning commission breached a statutory obligation to consider whether its approval of the mine expansion should be “issued subject to conditions aimed at ensuring ... that greenhouse gas emissions are minimized to the greatest extent practicable.” Since the commission did not consider imposing mitigation requirements for the emissions linked to the project, nearly all of which come downstream from the eventual burning of the coal, the court said the approval was invalid.
The case concerned the commission’s 2022 authorization of an expansion of MACH Energy’s Mount Pleasant open-cut coal mine, located near the town of Muswellbrook in New South Wales. The expansion would extend the mine’s operation through 2048 and double the its extraction output, generating an additional 870 million metric tons of carbon pollution – 98 percent of which is categorized as “scope 3” emissions from the downstream burning of the exported coal.
A community group of farmers and local residents from the Upper Hunter Valley region, called Denman Aberdeen Muswellbrook Scone Healthy Environment Group (DAMS HEG), took legal action over the project’s approval. Following an initial dismissal of the case, an appeals court ruled in the group’s favor in July 2025, finding that the planning commission had failed to consider the localized climate impacts from the mine’s emissions. MACH Energy then mounted an appeal to the High Court, which heard the case in May.
The High Court ultimately found the mine expansion’s approval invalid on different grounds than the appeals court. The result was still a win for the Denman group, which celebrated the ruling in a press conference outside of the New South Wales Court of Appeal in Sydney on Wednesday.
“We’re so grateful for this decision. We can finally make a change in direction in our laws and reflect the need to consider the climate impacts of our scope 3 emissions from our coal that we export,” said Wendy Wales, a retired science teacher and farmer who is president of DAMS HEG.
“This case I think is a rally landmark case,” added Tony Lonergan, Wendy’s partner and treasurer of DAMS HEG. “Governments have to start getting serious about our emissions, the emissions from the coal and gas that we produce in our country.”
Anita Hart, principal lawyer at the firm Johnson Legal that represented the community group, called the High Court’s decision “groundbreaking.”
“It will have a huge impact here, as well as will be examined closely overseas,” Hart said.
“What the High Court has found in finding in our clients’ favor is that a coal mine can’t disregard its scope 3 emissions – the emissions burned overseas – and that, consistent with the International Court of Justice’s advisory opinion, the coal mine is responsible for those emissions and must look at what conditions if any can be imposed to reduce them.”
The International Court of Justice’s historic climate change advisory opinion, issued just hours before the New South Wales Court of Appeal ruling in this case last year, said that governments’ failure to protect the climate system from greenhouse gas emissions, through authorizing continued fossil fuel activities, could constitute an “internationally wrongful act.”
Legal experts say the ruling is also in alignment with decisions from courts in other countries, such as Norway and the UK, affirming that government authorities must take responsibility for scope 3 emissions in determining whether to approve fossil fuel projects.
Elaine Johnson, director of Johnson Legal, wrote in a social media post that the case’s impact “will reverberate around the world,” since Australia is the world’s second largest exporter of coal.
“We’re still approving major coal mine expansions in New South Wales and Queensland,” Johnson said at the press conference. But the High Court’s decision, she noted, means that “our planning authorities can no longer turn a blind eye to the emissions that we’re exporting overseas.”
Just a week before the High Court issued its decision, the New South Wales Independent Planning Commission gave the green light to another major coal expansion called the Hunter Valley Operations Continuation Project, the biggest ever proposed in the state. That approval is now “likely to run into significant legal difficulty,” according to the New South Wales Greens.
“Lawyers should be running to the Courts right now with this judgement in hand, ready to stop coal approvals in their tracks,” Sue Higginson, Greens MP spokesperson for climate change and public interest environmental lawyer, said in a statement.
Legal and climate accountability experts at the University of Melbourne write in a new piece in The Conversation that the ruling “could sour the economic argument for developing new coal and gas projects in New South Wales, and possibly Australia.”
“It directly affects the 17 other coal proposals currently in the state’s planning pipeline,” they write. “It could also provide a legal blueprint for how courts across the country handle future cases against fossil fuel projects.”
“The case now returns to the NSW Land and Environment Court, which can suspend the operation of the mine or set conditions on its scope 3 emissions,” they added. “The latter option, however, may be extremely expensive for MACH Energy.”
In a statement responding to the High Court ruling, MACH Energy said it is disappointed with the outcome but accepts the decision.
“We will continue to actively pursue all available options to ensure the long-term continuity of the Mount Pleasant Operation,” the company said.
