Australian high court rejects Mount Pleasant coalmine expansion appeal

Ruling requires planning bodies to weigh scope 3 emissions

Australia’s High Court issued the ruling in a 3-2 split, with a majority of judges finding the state planning commission was required and failed to consider imposing conditions aimed at minimizing scope 3 emissions to the greatest extent possible — emissions generated when the coal is sold and burnt overseas.

The case stems from a challenge by Dams Heg, a community group in the Hunter Valley, to MACH Energy’s proposed Mount Pleasant Optimisation project. The Guardian reported the expansion would have doubled the mine’s output to 21 million tonnes per annum and run until 2048, with 98% of projected emissions classified as scope 3. The mine is located in Muswellbrook in the Hunter Valley region of New South Wales.

Wendy Wales, a retired science teacher and president of Dams Heg, said: “Today the high court has said what we have always known: we cannot dig up coal, ship it overseas, watch it drive climate change, and then pretend the consequences have nothing to do with us and won’t be felt by us.”

“The droughts, the bushfires, the floods – are directly connected to greenhouse gases, and massive fossil fuel projects like Mt Pleasant Optimisation simply ‘add fuel to the fire’,” she said. “We can’t ignore physics, chemistry and biology. We must live within nature’s limits and this ruling endorses that.”

Wales said the ruling was an acknowledgment that many Australians had “already suffered extreme weather devastation” and called on lawmakers to turn their “full attention” to addressing climate change. “Now the true and complete long term costs of export coal on Australians, via the climate impact from burning that coal, must be considered,” she said.

The proceedings, brought by MACH Energy, were the first time Australia’s highest court had been asked to consider a case on climate change grounds. The Guardian reported that advocates said the judgment sets a binding national precedent for fossil fuel projects in New South Wales.

MACH had appealed a 2025 decision by the NSW Court of Appeal that overturned the expansion of the company’s Mount Pleasant mine. The court of appeal had found the NSW Independent Planning Commission was required and failed to consider the impacts of all emissions associated with the project on the local environment.

In the initial proceedings brought by the community group in the NSW Land and Environment Court, that court ruled in favor of MACH Energy. Wales, her partner Tony Longeran, and the Dams Heg community group have pursued the case through the courts for more than four years.

The Guardian reported that comment was being sought from MACH Energy at the time of publication.