A landmark ruling in the High Court has found planning authorities are required to consider the emissions caused by burning fossil fuels overseas when approving projects.

Three of the five judges found in favour of a Hunter Valley residents' group, which halted the Mount Pleasant mine expansion last year in the New South Wales Court of Appeal.

The High Court has agreed with that judgement and found the project's planning approval needed to take into account scope 3 emissions, which are emitted when the coal is burnt, as opposed to scope 1 and 2 emissions, which are directly caused by the mine.

The case is expected to have national implications for the way fossil fuel project approvals take global emissions and local climate change impacts into account.

The High Court case centred around an open-cut coalmine near Muswellbrook, which was approved for expansion by NSW planning authorities in 2022, before being halted through a community-led court battle last year.

MACH Energy, which operates the mine, wants to extract a total of 444 million tonnes of coal from the site, almost doubling the amount currently produced per year, until 2048.

Because the thermal coal is for export, the more than 870 million tonnes of carbon dioxide-equivalent emissions caused by its combustion will occur in other countries.

They are known as scope 3 emissions and are not accounted for in Australia's greenhouse gas inventory.

Residents from the Denman Aberdeen Muswellbrook Scone Healthy Environment Group (DAMSHEG) have fought to block the expansion on the grounds that those "downstream" emissions will also cause climate-related harms locally and should have been considered as part of the planning process.

In July 2025, the NSW Court of Appeal agreed that the project's global emissions would cause local climate change impacts and that the Independent Planning Commission's 2022 approval did not take this into account.

More to come.