SYDNEY/PERTH - An Australian community group has won the first climate change case to come before the country's top court, with judges upholding a decision to block a two-decade extension of a coal mine in the State of New South Wales.

MACH Energy had sought to extend the life of its Mount Pleasant mine, which is due to end operations in December this year, until 2048 and double its coal production. The expansion would have allowed it to extract an additional 406-million tons of coal.

The High Court of Australia, in dismissing the company's appeal with costs, found local authorities failed to properly consider imposing rules to mitigate the project's climate footprint, a ruling advocates say will impact future fossil fuel approval decisions in the state.

So-called scope 3 emissions made up 98% of the mine's greenhouse gas emissions. But the New South Wales' Independent Planning Commission did not consider rules to address them as the vast majority would be generated overseas once the coal was exported, said Justice James Edelman.

"By focusing only upon 2% of the project's emissions, the Commission failed in its reasons to consider whether conditions should be imposed to ensure that greenhouse gas emissions are minimised to the greatest extent practicable."

Projects with a direct emissions footprint of more than 100 000 metric tons of carbon dioxide equivalent, known as Scope 1 and 2 emissions, are covered by Australian rules that require an emissions fall of 4.9% a year or the use of offsets, or carbon credits.

Emissions created overseas by the use of fossil fuels are not covered.

The appeal was the first time Australia's highest court had ruled on a climate change 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," said Wendy Wales, a retired science teacher and the community group's president.

MACH Energy said in a statement it acknowledged the decision but was "disappointed".

A WIDER THREAT

The judgment has drawn both criticism and praise.

Western Australia’s Chamber of Minerals and Energy (CME) CEO Aaron Morey said the decision created “fresh uncertainty” for his State’s liquefied natural gas industry.

“All it will do is drive investment in those projects to competing countries – many of which enforce much lower environmental and safety standards than Australia does,” he said.

Woodside Energy’s vast Browse gas project has faced opposition on climate grounds with the Australian Conservation Foundation bringing its own case.

Astrid Puentes Riano, the ​UN's special rapporteur on the Human Right to a Clean, Healthy and ​Sustainable Environment, will join as an amicus curiae or ‘friend of the court’.

Minerals Council of Australia (MCA) CEO Tania Constable said it sent “a very negative signal to Australia's trade and investment partners about sovereign risk in this market”.

Latest government figures show Australia shipped 209-million metric tons of thermal coal for earnings of A$31-billion ($21.62-billion) in 2026-2027. Liquefied natural gas exports were valued at A$70-billion.