Australia’s highest court has put a stop to a coal expansion that would have doubled output at one of New South Wales’ mines. On Wednesday, October 7, the High Court ruled in a 3-2 split that the approval of MACH Energy’s Mount Pleasant expansion in Muswellbrook was invalid. It dismissed the company’s appeal.
The stakes are large. The expansion would double the mine’s coal output to 21 million tonnes a year until 2048, and some 98 percent of its projected emissions are scope 3 emissions, the greenhouse gases released when the coal is sold and burned overseas.
What the court found
A majority of the judges found that the Independent Planning Commission, the state’s planning body, was required to consider how to mitigate those emissions and failed to do so. It never considered imposing conditions to minimise them to the greatest extent possible. The case is the first time Australia’s highest court has been asked to consider climate change, and advocates say it sets a binding national precedent for fossil fuel projects in New South Wales.
The High Court reached its conclusion on a different basis from the NSW court of appeal, which had overturned the expansion in 2025. MACH appealed that decision. The Land and Environment Court had ruled for the company in the first round.
The community group
The challenge came from the Denman Aberdeen Muswellbrook Scone Healthy Environment Group. Its president, retired science teacher Wendy Wales, and her partner Tony Lonergan have pursued the case for more than four years. “Today the high court has said what we have always known,” Wales said. “We cannot dig up coal, ship it overseas, watch it drive climate change, and then pretend the consequences have nothing to do with us.”
Elaine Johnson, director of Johnson Legal, which represented the group, said planning authorities must now consider how to limit emissions from coal burned overseas. “Given that Australia is the second-largest exporter of coal in the world, this is a very significant judgment,” she said.
Industry and political reaction
A MACH Energy spokesperson said the company was disappointed but accepted the decision. It will review the judgment and “continue to actively pursue all available options” to keep Mount Pleasant running. The spokesperson noted that the state’s approval of a separate modification in August would extend the mine’s operational life by six years, and said thousands of Hunter residents rely on it for work and income.
Tania Constable, chief executive of the Minerals Council of Australia, called the ruling “a further blow to Australia’s prospects of meeting continued demand for our high-quality coal from global customers.” She added: “Now mines may have to work out how to reduce emissions from their export customers.”
NSW Greens MP Sue Higginson said the decision could create “significant legal difficulty” for the Hunter Valley Operations extension, the biggest in the state’s history, which the Independent Planning Commission approved a week earlier.
