The High Court of Australia is set to hear the nation’s first-ever climate change case, a landmark moment that will determine a binding national precedent on whether Australian planning authorities are legally required to consider local climate impacts when approving fossil fuel projects.
The case, MACH Energy Australia Pty Ltd v Denman Aberdeen Muswellbrook Scone Healthy Environment Group Inc (DAMS HEG), centres on a grassroots challenge against the expansion of the Mount Pleasant open-cut coal mine in the Hunter Valley.
If allowed to proceed, the optimisation project would double the mine’s output and extend its life to 2048, releasing an estimated 870 million tonnes of carbon dioxide.
In July 2025, the NSW Court of Appeal delivered a unanimous, groundbreaking verdict, ruling the mine’s approval unlawful. The court found that authorities have a mandatory legal obligation to consider the specific local climate harms caused by a project’s downstream emissions, the carbon released when the coal is eventually burned. MACH Energy is now seeking to have that ruling overturned.
The case arrived at an extraordinary moment. The High Court hearing follows a significant advisory opinion from the International Court of Justice (ICJ) in The Hague, which recently rejected Australia’s arguments and found that fossil-fuel exporting nations bear legal responsibility for the climate harm caused by their exports.
The global significance of the case is underscored by the intervention of elite institutions. The High Court has granted leave to legal and scientific experts from the Universities of Cambridge, Columbia, and Melbourne, alongside the Union of Concerned Scientists, to support the Hunter Valley community group.
Professor Nicole Rogers of Bond University described the hearing as a watershed moment in Australian law.
“Courts around the world — from The Hague to London to Canberra — are being asked the same fundamental questions: can legal systems keep pace with the climate crisis and to what extent are decision makers who continue to approve fossil fuel projects accountable for climate impacts?
“The Mount Pleasant case is Australia’s latest contribution to that global conversation, and the High Court’s answer will be studied by others well beyond the Upper Hunter Valley.”
For Wendy Wales, President of DAMS HEG and a retired science teacher, the case is a matter of survival for the Upper Hunter.
“Our communities are enduring increasingly terrifying climate disasters,” she said.
“We have felt the catastrophic impacts of droughts, bushfires, floods and a myriad of other tragic events. The short-term economic benefits cannot be given priority over the exponentially increasing long term consequences.”
The High Court’s decision will directly impact 18 coal proposals currently in the NSW planning pipeline and provide the legal foundation for future climate litigation across the country.