MACH Energy Australia Pty Ltd v. Denman Aberdeen Muswellbrook Scone Healthy Environment Group Inc

Denman Aberdeen Muswellbrook Scone Healthy Environment Group Incorporated (DAMSHEG), a community environmental organization, brought judicial review proceedings in the Land and Environment Court of New South Wales challenging a development consent granted by the Independent Planning Commission of New South Wales (IPC). On September 6, 2022, the IPC approved MACH Energy Australia Pty Ltd’s proposal to extend the operation of the Mount Pleasant open cut coal mine in the Upper Hunter region of New South Wales for an additional 22 years. The proceedings were brought as a Class 4 judicial review under the Land and Environment Court Act 1979 (NSW), which allows challenges to the legal validity of administrative decisions made under planning and environmental legislation. DAMSHEG alleged that the IPC’s decision was legally invalid on multiple grounds. Among other arguments, the applicants contended that the Commission failed to properly consider the likely impacts of the project’s greenhouse gas emissions, including Scope 3 emissions arising from the downstream combustion of coal, and failed to consider expert evidence and submissions addressing those impacts. DAMSHEG also argued that the Commission’s reasoning was illogical and that the decision failed to meet the standard of legal reasonableness. Finally, DAMSHEG argued that the Commission failed to consider the likely environmental impacts of climate change on the locality in which the mine would operate. On August 19, 2024, Justice Robson dismissed the application. The Court emphasized that judicial review proceedings do not involve reconsidering the merits of the decision, but rather assessing whether the Commission complied with the statutory framework governing development approvals. Justice Robson concluded that the IPC had considered relevant environmental factors, including greenhouse gas emissions and air quality impacts, and had imposed conditions requiring compliance with specified air quality criteria. The Court therefore found no jurisdictional error in the Commission’s approval of the project. DAMSHEG appealed the decision to the New South Wales Court of Appeal. Following a hearing on May 26, 2025, the Court of Appeal (Ward P, Adamson JA, and Price AJA) allowed the appeal on July 24, 2025 and declared the development consent invalid. The Court focused on s 4.15(1)(b) of the Environmental Planning and Assessment Act 1979 (NSW), which requires consent authorities to consider the likely environmental impacts of a proposed development. The Court held that the IPC had failed to consider a mandatory statutory consideration by not addressing how climate change itself could affect the locality in which the project would operate. In particular, the Court explained that an assessment of the “likely impacts” of a development may require consideration not only of how the project contributes to global climate change through greenhouse gas emissions, but also how climate change may affect the local environment and community during the life of the project. The Commission had considered greenhouse gas emissions associated with the project, but it did not consider the effects of climate change on the Upper Hunter region over the period in which the mine would operate. The Court rejected the argument that the widely accepted nature of climate change impacts excused the Commission from explicitly addressing those impacts in the local planning context. Even if climate change impacts are scientifically established, the decision maker must still consider how those impacts interact with the particular development and its locality. The Court therefore concluded that the Commission failed to comply with the statutory obligation in s 4.15(1)(b) to consider the likely environmental impacts of the development. As a result, the development consent was declared invalid. The Court remitted the matter to the Land and Environment Court to determine whether further orders could be made. On August 21, 2025, MACH Energy applied for special leave to appeal in the High Court of Australia. On December 4, 2025, that application was granted. DAMSHEG went on to file a Notice of Contention contending that the Court of Appeal erred in failing to find that the Commission did not take into consideration, in the manner required by s 4.15(1)(b) of the Environmental Planning and Assessment Act 1979 and cl 2.20 of the State Environmental Planning Policy (Resources and Energy) 2021, whether the development consent should be issued subject to conditions aimed at ensuring that greenhouse gas emissions (including downstream emissions) of the development are minimized to the greatest extent practicable. The High Court also granted leave for Melbourne Climate Futures, the Union of Concerned Scientists, the Center for Climate Engagement and the Sabin Center for Climate Change Law to be heard as amici curiae. On October 7, 2026, the High Court of Australia delivered its judgment. The High Court unanimously held that the IPC had complied with s 4.15(1)(b) of the Environmental Planning and Assessment Act 1979. In other words, the High Court rejected the Court of Appeal's conclusion that the IPC had failed to consider the likely local environmental impacts of the development. The High Court therefore found that it was not necessary to decide whether climate change itself could constitute an environmental impact 'in the locality' for the purposes of s 4.15(1)(b). However, by majority, the High Court upheld the ground concerning the IPC's obligations under cl 2.20(1)(c) of the State Environmental Planning Policy (Resources and Energy) 2021 (therefore granting leave for DAMSHEG to file its Notice of Contention). That provision required the Commission to consider whether the development consent should be subject to conditions aimed at ensuring that greenhouse gas emissions were minimized to the greatest extent practicable. The majority found that the IPC had failed to properly consider whether conditions should be imposed to minimize the project's greenhouse gas emissions, including its Scope 3 emissions. Scope 3 emissions represented approximately 98% of the project's total predicted greenhouse gas emissions, but the Commission's consideration of those emissions was insufficiently 'limited to an analysis of whether they were 'appropriately regulated and accounted for through broader national policies and international agreements (such as the Paris Agreement)' (Gordon J at [182]). The High Court has remitted the matter to the Land and Environment Court to determine whether MACH Energy's development consent can be remedied via terms of consent, or whether it must be declared invalid, in whole or in part.

MACH Energy's submissions in reply

Amicus Brief submitted by the Centre for Climate Engagement at Hughes Hall, University of Cambridge and the Sabin Center for Climate Change Law at Columbia Law School

First respondent's submission.

Notice of filing.

Chronology.

Commission's permit quashed.

Application dismissed at Land and Environment court.