The High Court blocks a major NSW coal mine extension over its emissions, in a ruling that could reopen other approvals
By a 3–2 majority, the court held the planning commission failed to consider conditions on the mine's downstream emissions. Climate groups cheered, miners warned of lost investment and one lawyer called it a Pandora's box.
The High Court of Australia dismissed an appeal by MACH Energy on Wednesday, ending the company's attempt to restore approval for a 22-year extension of the Mount Pleasant coal mine in the Hunter Valley. The ABC, SBS, the Sydney Morning Herald, The Age, the Guardian and the Australian Financial Review all reported the decision, which the ABC described as a massive shake-up for coal and gas and which is the first ruling from the nation's highest court on how far a planning decision must look at climate effects. Three of the five judges, Justices Gordon, Edelman and Beech-Jones, found that the NSW Independent Planning Commission had not discharged its statutory obligations. The commission imposed conditions on the mine's own emissions, which are a small share of the total, but did not consider whether to impose conditions to minimise the so-called scope 3 emissions, the greenhouse gases released when the coal is burned overseas. Reports put that downstream share at about 98 per cent of the project's total. Chief Justice Gageler and Justice Jagot dissented on that point.
The case now goes back to the commission to be assessed again in accordance with the law. The decision is narrower than some headlines suggest. All five judges agreed on a separate issue, that the commission had met its duty to consider the likely environmental impacts of the project, and they rejected the NSW Court of Appeal's reasoning on that duty. The court did not decide the larger question of whether climate change is an environmental impact in the locality of a development, which commentators say was left open. The challenge was brought by a local community group, the Denman Aberdeen Muswellbrook Scone Healthy Environment Group. The NSW Court of Appeal had invalidated the approval in July 2025, and the High Court agreed to hear the appeal in December and heard it in May. Reports also say a separate, later approval allows the mine to keep operating to about 2032, which was not part of the appeal; we have not confirmed that against planning records.
Reaction split quickly. SBS reported celebrations among campaigners, one of whom said the planning process had been exposed for the sham it is. A NSW MP told the Guardian that lawyers should be running to the courts to stop coal approvals. The Herald quoted a legal view that the ruling is a Pandora's box that could reopen coal mine approval cases. In the other direction, the AFR reported that miners warn the landmark ruling puts investment at risk, and ran a commentary urging calm because the High Court's coal mine judges are no climate activists. The Age said a legal reckoning has arrived for Australian mining. The decision does not stop Mount Pleasant or any other mine. It requires that decision-makers look at downstream emissions before approving them, and it leaves the political question, whether to approve the coal anyway, with the government.