24 US States Sue EPA Over Historic Repeal of the Climate Endangerment Finding

Overview

A coalition of 24 US states has launched legal action against the US Environmental Protection Agency (EPA) following its unprecedented decision to repeal the 2009 Endangerment Finding. This finding was the scientific and legal determination that greenhouse gas emissions endanger public health and welfare, and it served as the cornerstone of federal climate regulation in the United States for more than 15 years. The repeal dismantles the legal foundation for emissions standards under the US Clean Air Act, and its consequences are already rippling through global environmental compliance frameworks. For Australian environmental consultants and firms with exposure to US assets, this development introduces material uncertainty into carbon accounting, ESG due diligence, and cross-jurisdictional risk assessment.

Key details

The 2009 Endangerment Finding was established following the landmark 2007 US Supreme Court ruling in Massachusetts v. EPA, which held that the EPA had the authority and obligation to regulate greenhouse gases as air pollutants under the Clean Air Act. The finding provided the statutory basis for federal vehicle tailpipe emission standards, industrial greenhouse gas reporting requirements, and new source performance standards for power plants.

The repeal removes this legal underpinning entirely. Without the Endangerment Finding, the EPA loses its mandate to regulate greenhouse gas emissions at the federal level. This means federal reporting programmes such as the Greenhouse Gas Reporting Program (GHGRP) face legal challenges, vehicle emission standards may revert to weaker benchmarks, and new industrial facilities in the US may no longer be required to implement best available control technology for carbon dioxide and methane.

The 24-state coalition argues that the repeal is scientifically indefensible and procedurally flawed. They contend that the EPA failed to provide new scientific evidence to justify reversing its own prior finding, and that the decision was politically motivated rather than grounded in the technical record. The legal challenge is expected to progress through the federal courts over the coming months, with potential implications for the scope of executive power over environmental regulation.

Australian context

While US federal climate policy retreats, Australia is accelerating its regulatory trajectory. The divergence creates a complex compliance landscape for firms operating across both jurisdictions.

In New South Wales, the EPA is enforcing greenhouse gas reporting requirements for coal mines and Safeguard Mechanism facilities, with mandatory reporting commencing in February 2026. Fugitive methane abatement requirements are being phased in from 2027, adding further obligations for resource sector operators. At the federal level, the reformed Safeguard Mechanism continues to tighten baseline emissions allocations for Australia’s largest industrial emitters.

The Climate Change Authority’s latest review has recommended strengthening Australia’s Nationally Determined Contribution under the Paris Agreement, and the Australian Securities and Investments Commission (ASIC) is increasing scrutiny of greenwashing claims and ESG disclosures by listed companies. The Australian Accounting Standards Board (AASB) is also progressing mandatory climate-related financial disclosures aligned with ISSB standards.

For practitioners, this regulatory asymmetry means that environmental due diligence on transnational portfolios now requires bifurcated risk models. A manufacturing facility or resource project in the US may face negligible federal climate compliance costs, while a comparable operation in Queensland or New South Wales will require extensive baseline emissions profiling, mandatory abatement capital expenditure, and rigorous disclosure under evolving Australian frameworks.

Practical implications

Environmental consultants advising clients with US and Australian operations should take note of several practical consequences arising from this development:

• ESG due diligence: Phase 1 Environmental Site Assessments and transaction due diligence for US assets should now include a specific assessment of regulatory risk arising from the absence of federal climate mandates. This includes evaluating state-level climate laws, which vary significantly across the US.
• Carbon accounting divergence: Corporate carbon inventories that span both jurisdictions will need to account for differing reporting boundaries, emission factors, and regulatory thresholds. The removal of federal GHGRP obligations in the US may result in data gaps that complicate Scope 1 and Scope 2 reporting under Australian frameworks.
• Litigation risk: The multi-state lawsuit introduces uncertainty about the permanence of the repeal. Clients making long-term capital investment decisions in the US should be cautioned that the Endangerment Finding could be reinstated by a future administration or by court order.
• Supply chain implications: Australian firms importing goods from US manufacturers may face increasing pressure to demonstrate that their supply chains meet Australian ESG and climate disclosure standards, regardless of the regulatory environment at the point of manufacture.

References and related sources

This article is based on reporting by the California Attorney General’s Office (OAG). Related regulatory frameworks include the US Clean Air Act, the NGER Act 2007 (Cth), the Safeguard Mechanism, and the AASB climate disclosure standards. The PFAS NEMP 3.0 (March 2025) and NEPM 2013 provide context for broader contaminated land regulatory trends in Australia.

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How iEnvi can help

iEnvi provides specialist environmental consulting services for clients navigating complex regulatory landscapes. Our contaminated land team can assist with environmental due diligence on transnational portfolios, including Phase 1 and Phase 2 assessments. For clients managing emissions obligations under the Safeguard Mechanism or state-based frameworks, our team delivers practical compliance strategies and risk assessments. If you require expert witness services for regulatory disputes or litigation involving environmental compliance, our experienced practitioners can assist.

This is an iEnvi Machete news summary. Prepared by iEnvi to summarise the source article for contaminated land, groundwater, remediation, approvals and site risk professionals.

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