The High Court, Scope 3 GHG Emissions And What It Means For Development Applications

This week, the High Court of Australia, comprising Justices Gageler, Gordon, Edelman, Jagot and Beech-Jones, delivered judgment in the matter of Mach Energy Australia Pty Ltd v Denman Aberdeen Muswellbrook Scone Healthy Environment Group Inc & Anor [2026] HCA 35. The case has attracted significant media attention, painting its impact in various lights. But what does the case really mean for applicants and consultants?

The Mount Pleasant coal mine, owned by Mach Energy Australia Pty Ltd (MACH), is an open cut mine in the Hunter Valley, New South Wales (NSW).

The ‘state significant development’ application made by MACH to the NSW Department of Planning and Environment (the Department), had included an environmental impact statement (EIS), which included ‘potential impacts of the Project’ and ‘potential impacts on the Project’. The EIS addressed greenhouse gas emissions (GHG), covering Scope 1, 2 and 3 emissions – but mitigation measures offered only in terms of the Scope 1 and Scope 2