Australia's High Court Voids Coalmine Expansion, Setting Climate Precedent

In a 3-2 decision that marks the first time Australia's highest court has weighed climate change as grounds for overturning a major fossil fuel project, the nation's High Court ruled this week that the approval of MACH Energy's Mount Pleasant coalmine expansion in Muswellbrook was invalid. The community group that brought the case—the Denman Aberdeen Muswellbrook Scone Healthy Environment Group, known as Dams Heg—pursued the matter through the courts for more than four years, winning at the High Court level after an earlier loss in the land and environment court and a subsequent victory in the NSW court of appeal that MACH then appealed.

The core of the judgment centers on what regulators failed to do. When the Independent Planning Commission approved the expansion, it did not impose conditions to minimize the greenhouse gas emissions that would result when the coal is exported and burned overseas—what the court calls scope 3 emissions. The majority of judges found this omission unlawful. The Mount Pleasant expansion would have doubled the mine's annual output to 21 million tonnes through 2048, with roughly 98 percent of the projected emissions occurring after the coal leaves Australian shores. The court determined that planning authorities are required to consider how to mitigate these overseas emissions to the greatest extent possible, and the commission had simply failed to do so.

Wendy Wales, a retired science teacher and president of Dams Heg, framed the ruling in terms of accountability. "We cannot dig up coal, ship it overseas, watch it drive climate change, and then pretend the consequences have nothing to do with us," she said. Wales pointed to the direct connection between greenhouse gas emissions and the extreme weather events Australians have already endured—droughts, bushfires, floods. She called on lawmakers to redirect their full attention toward addressing climate change rather than continuing to approve projects that export the problem elsewhere.

Elaine Johnson, the lawyer who represented Dams Heg, emphasized the significance for Australia's role as the world's second-largest coal exporter. "The court has said that when considering coalmine expansions, our planning authorities must consider how to limit emissions generated from coal burned overseas," Johnson said. This requirement now stands as binding precedent for future fossil fuel approvals in New South Wales.

The timing of the judgment creates immediate legal jeopardy for other projects. Just one week before the High Court ruling, the Independent Planning Commission approved the Hunter Valley Operations coalmine extension—the largest in the state's history. That project carries the same emissions profile as Mount Pleasant: 98 percent of its emissions are scope 3 emissions. Critically, the environmental impact statement for HVO did not even account for scope 3 emissions at all. Sue Higginson, NSW Greens MP and climate change spokesperson, said the High Court decision could create "significant legal difficulty" for HVO's approval and called on lawyers to use the judgment to challenge other coal approvals.

MAC Energy said it was disappointed but accepted the court's decision. The company stated it would review the judgment to understand its implications for future assessments and would continue pursuing "all available options" to ensure the long-term operation of Mount Pleasant. The company also noted that the state government had approved a separate modification to the mine in August that would extend its operational life by six years. A MACH spokesperson added that thousands of Hunter Valley residents depend on the mine for employment and income and have "lived with fear and uncertainty for too long."

Tania Constable, chief executive of the Minerals Council of Australia, described the ruling as "a further blow to Australia's prospects of meeting continued demand for our high-quality coal from global customers." She suggested that mines may now have to work out how to reduce emissions from their export customers—a prospect that underscores how fundamentally the High Court decision reshapes the regulatory landscape for fossil fuel projects in Australia.