Australia's High Court handed down its decision on 7 October 2026, with a 3-2 majority rejecting MACH Energy's appeal. MACH Energy must also pay the case costs. The company had sought to extend the Mount Pleasant coal mine in New South Wales's Hunter region for 22 years until 22 December 2048, increasing annual production from 10.5 million to 21 million tonnes, yielding an additional 406 million tonnes of coal.
Four years through three court levels
The case was brought by DAMSHEG, the Denman Aberdeen Muswellbrook Scone Healthy Environment Group, a local citizens' campaign from the Upper Hunter Valley. They pursued it across three court levels over four years. The New South Wales Independent Planning Commission conditionally approved the original Mount Pleasant project in September 2022 despite DAMSHEG's opposition based on greenhouse gas emissions. DAMSHEG appealed to the Land and Environment Court but initially lost. In July 2025, New South Wales's Court of Appeal sided with the group and invalidated the approval, ruling the Commission had failed to account for the local climate impacts of emissions released abroad. The High Court unanimously found the Commission had satisfied its obligation to consider impacts. But a majority determined that the approval was invalid for another reason: the Commission had not examined possible conditions to minimize emissions, particularly Scope 3 emissions. The appellate court sent the case back for assessment of whether the approval could stand if certain conditions were imposed.
Two percent scrutinized, 98 percent overlooked
According to Reuters, Scope 3 emissions—mostly released after coal is exported and burned abroad—account for 98 percent of the mine's total greenhouse gas footprint. Justice James Edelman told the planning commission that by focusing on the remaining 2 percent, it had failed to consider conditions for the greatest practical reduction in all emissions. The judgment set total emissions at 876.07 million tonnes, with 860 million tonnes as Scope 3 emissions. Legal analyst Kate Owens noted that the High Court did not rule that Scope 3 conditions must ultimately be imposed, only that the question must be properly examined. The law still allows such conditions to be rejected as impractical. DAMSHEG president Wendy Wales commented: you cannot export coal, send it abroad, watch it drive climate change, and then pretend it has nothing to do with you. Lawyer Anita O'Hart argued the High Court confirmed that planning authorities cannot ignore the causal chain of a project's emissions, making this obligation binding across New South Wales's entire planning system. MACH Energy said it was disappointed but accepted the decision and would study implications for future project reviews. The Minerals Council of Australia called it a further setback for Australia's ability to meet international customers' ongoing demand for coal.
Comparable precedents: The Paris Agreement is not an excuse
The International Court of Justice held a similar principle in a July 2025 legal opinion: countries like Australia remain responsible for emissions even when their fossil fuels are shipped to another country for burning. The UK's Supreme Court also ruled in 2024, after local resistance to an oil drilling project in Surrey, that planning authorities must assess the future climate impacts of fossil projects before approval. For the HVO project, Green Party spokeswoman and environmental lawyer Sue Higginson criticized its environmental statement for omitting Scope 3 emissions entirely, suggesting the approval fails the High Court's new standard. By comparison, the proposed Mount Pleasant expansion would have added roughly twice as much greenhouse gas as Australia's entire annual emissions. Former Australian Chief Scientist Penny Sackett estimated it would rank among the world's 650 largest greenhouse gas-emitting projects or activities.
Continued operation, possible review, and political pressure
New South Wales government officials noted that Mount Pleasant holds a separate approval to operate until 2032. The ruling does not change that. Officials emphasized the decision concerns how the expansion was reviewed in 2022 under the previous government and does not exclude a future review or future approvals of coal mine expansions. MACH Energy has signaled it will continue exploring options for the project. Officials said they would work closely with the company. Opposition leader Angus Taylor called it absurd to require New South Wales planning authorities to account for climate impacts in other countries and, with Matt Canavan, urged the Albanese and Minns governments to immediately change the law. According to Liz Hicks of the University of Melbourne, the ruling primarily affects New South Wales projects with limited direct impact on other states, but courts nationwide monitor such decisions. Federal Environment Minister Murray Watt said the decision does not automatically transfer to Commonwealth decisions or legislation.