Australia's High Court has ruled, 3-2, that NSW's Independent Planning Commission (IPC) must consider imposing conditions to minimise all greenhouse gas emissions from the Mount Pleasant coalmine — including scope 3 emissions generated when exported coal is burned overseas.

The decision, delivered in MACH Energy's appeal over its Hunter Valley mine, upheld the NSW Court of Appeal's July 2025 finding that the IPC's 2022 approval of the mine's expansion failed a statutory requirement. That requirement obliges the Commission to "ensure greenhouse gas emissions are minimised to the greatest extent possible".

What was the case about?

MACH Energy operates the Mount Pleasant open-cut mine near Muswellbrook. The company wants to double its coal exports, extract more than 440 million tonnes, and keep the mine open until 2048.

The IPC approved the expansion in 2022. The Denman Aberdeen Muswellbrook Scone Healthy Environment Group (DAMSHEG), led by two retired schoolteachers, challenged that approval. The group argued the panel failed to properly consider harm that climate change — driven by the exported coal's downstream scope 3 emissions — would cause to the Hunter region.

In July 2025 the NSW Court of Appeal agreed with DAMSHEG. The court found none of the IPC's conditions expressly addressed scope 3 emissions, and sent the matter for review in the Land and Environment Court. MACH Energy, frustrated by the delays and seeking clear guidance, took the case to the High Court.

What does the ruling change?

The IPC had accepted that 860 million tonnes of emissions would be generated overseas from the project and would contribute to climate change. It concluded those emissions "would be accounted for" by importing countries "through broader national policies and international agreements (such as the Paris Agreement)".

MACH Energy pressed the same argument on appeal. The High Court rejected it by majority.

The court held NSW law required the IPC to "consider imposing conditions to minimise to the greatest extent practicable all greenhouse gas emissions, including Scope 3 emissions". Justice Gordon wrote: "The impact of greenhouse gas emissions is the same, regardless of how they are categorised." Paris Agreement accounting by other countries did "not address the Commission's obligation", she found.

University of Melbourne professor Jacqueline Peel called it a "very unusual case" for the High Court to take up, describing it as "largely an issue of statutory interpretation, what the words of the statute meant".

Why are the stakes so high?

The extension of the Mount Pleasant mine would add roughly twice Australia's total annual greenhouse gas emissions to the atmosphere.

Professor Peel said the narrowest reading of the ruling simply enforces NSW planning law as it already existed. The bigger change, she said, is the High Court "saying the quiet part out loud": "If you start requiring mines to actually deal with and be accountable for their scope 3 emissions and have to do something to minimise those, then it makes the coal mine a much different economic prospect."

Adam Bandt of the Australian Conservation Foundation said governments and corporations had long fought this outcome. "There came a time when we understood that asbestos was a product that when you used it as intended would cause harm," he said. "That's now the same with coal and gas."

The Minerals Council's Tanya Constable said she was "very concerned about the decision". "This will send shudders down everybody's spine," she said.

How does it fit the global picture?

Opposition Leader Angus Taylor called the ruling "absurd", arguing: "Under the international rules … emissions are counted where coal is used, not where it is mined."

Those rules are shifting. In July 2025 the International Court of Justice issued an advisory opinion placing accountability for climate-related harm on fossil fuel producers at the point of extraction. The UK Supreme Court has also ruled that planning bodies must assess the future impact of fossil fuel projects.

What happens next?

NSW Premier Chris Minns warned activists not to "get overexcited", noting the operator is still "looking to continue an application through the IPC". Federal Industry Minister Tim Ayres called the decision "not a big deal" and "confined to the provisions of the NSW Act".

Professor Peel expects new litigation. "Groups will now want to explore what that added set of arguments from the High Court decision might offer in terms of challenging approvals for fossil fuel projects," she said. For practitioners, the immediate consequence is that NSW consent authorities conditioning resource projects must squarely address downstream emissions — and approvals that do not face appeal risk.