Australian High Court invalidates mine approval over Scope 3 mitigation analysis

On October 7, 2026, the High Court of Australia dismissed MACH Energy's appeal in MACH Energy Australia Pty Ltd v Denman Aberdeen Muswellbrook Scone Healthy Environment Group Inc, leaving the Mount Pleasant expansion approval invalid. Reporting on the judgment said the planning authority had failed to consider conditions that could minimize emissions from coal sold and burned overseas; the proposed expansion would have doubled output to 21 million tonnes annually through 2048, with approximately 98% of projected emissions classified as Scope 3. Project sponsors should now treat downstream-emissions analysis and mitigation conditions as core approval evidence in New South Wales, even where the emissions occur outside Australia. Counsel should watch how agencies reopen affected approval processes and whether litigants apply the reasoning to other fossil-fuel and infrastructure projects.