MACH Energy Australia seeks to overturn a ruling that found planning authorities must weigh scope three emissions from the mine’s coal exports.
On Wednesday, the High Court began hearing a challenge brought by the Denman Aberdeen Muswellbrook Scone Healthy Environment Group against the Mount Pleasant coal mine expansion near Muswellbrook, seeking to overturn a ruling that declared the project's approval unlawful.
The NSW Court of Appeal ruled in July 2025 that the mine's approval was unlawful, finding planning authorities must consider climate impacts from Scope 3 emissions, prompting MACH Energy Australia to ask the High Court to overturn that decision.
DAMSHEG lawyers argue the mine contributes 0.065 per cent of annual global anthropogenic emissions, with Scope 3 emissions representing 98 per cent of the project's total, citing Intergovernmental Panel on Climate Change findings that "every tonne of CO2 emissions adds to global warming."
Mine operators contend the Environmental Planning and Assessment Act does not require a causal enquiry into climate change impacts "in the locality," whereas DAMSHEG argues international courts increasingly accept causal links between specific emission sources and climate impacts.
Wendy Wales, head of the Denman Aberdeen Muswellbrook Scone Healthy Environment Group, stated a favorable decision could "turn a super tanker around" by setting precedent as global courts face questions about accountability for fossil fuel project approvals.