Australia’s High Court has dismissed an appeal by MACH Energy and left standing the invalidation of a 22-year expansion of the Mount Pleasant coal mine in New South Wales.
The case concerned a 2022 planning approval that would have extended the Hunter Valley mine to 2048 and allowed annual production to rise to 21 million tonnes. A community group challenged the decision, arguing that the Independent Planning Commission had not properly considered the climate effects of emissions released when exported coal was eventually burned overseas.
By a three-to-two majority, the High Court agreed that the approval process failed to meet obligations imposed by New South Wales planning law. Scope 3 emissions—those produced beyond the mine itself, including by customers using the coal—accounted for about 98 per cent of the project’s expected greenhouse-gas footprint.
The governing rules required the Commission to consider the likely environmental effects of the development in the locality and whether conditions could minimise emissions to the greatest extent practicable. The majority held that the Commission’s reasoning did not show the legally required consideration of measures addressing the project’s much larger downstream emissions.
The judgment is important, but narrower than a general prohibition on new coal projects. It interprets the duties attached to this approval under New South Wales law. It does not prevent MACH Energy from seeking a fresh decision through a lawful process, and it does not shut the existing mine. The state government says a separate consent permits operations to continue until 2032.
The ruling nonetheless changes the legal terrain for future applications. Planning authorities considering large export projects will have to show that they have confronted downstream emissions and possible mitigation conditions, rather than treating combustion abroad as legally remote.
The case is MACH Energy Australia Pty Ltd v Denman Aberdeen Muswellbrook Scone Healthy Environment Group Inc, [2026] HCA 35. The judgment is final.
Read the High Court judgment and case materials.
