Hunter Valley community group wins landmark high court climate change case over Mount Pleasant coalmine

A Hunter Valley community group has won Australia’s first high court case to consider climate change, in a ruling advocates say sets a binding national precedent for fossil fuel projects in New South Wales.

In a landmark judgment, the nation’s highest court upheld a unanimous ruling by the NSW court of appeal that overturned MACH Energy’s proposed expansion of its Mount Pleasant coalmine in Musswellbrook.

In a 3-2 split ruling, the high court dismissed the coal company’s appeal, with a majority of judges finding the state’s planning commission was required and failed to consider how to mitigate the greenhouse gas emissions that would be generated by the mine when the coal is sold and burnt overseas.

A majority of the court found the Independent Planning Commission failed to consider imposing conditions aimed at minimising these emissions – known as Scope 3 emissions – to the greatest extent possible.

The Mount Pleasant expansion would double the mine’s coal output to 21m tonnes per annum until 2048 and 98% of the projected emissions are scope 3 emissions.

Wendy Wales is a retired science teacher and the president of the Denman Aberdeen Muswellbrook Scone Healthy Environment Group (DAMSHEG) — the community group that brought the original case.

“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,” she said.

“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”.

“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 acknowledgement that many Australians had “already suffered extreme weather devastation”. She said lawmakers needed 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 grounds.

MACH had appealed a 2025 decision by the NSW court of appeal that overturned a massive expansion of the company’s Mount Pleasant mine in Muswellbrook.

The court of appeal found in favour of the Denman Aberdeen Muswellbrook Scone Healthy Environment Group, ruling 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 Land and Environment Court, that court ruled in favour of MACH Energy. Wales, her partner Tony Longeran and the DAMSHEG community group have pursued the case through the courts for more than four years.