On July 29, 2025, the U.S. Environmental Protection Agency (EPA) published a notice of proposed rulemaking (NPRM) to repeal the 2009 Endangerment Finding. This action was driven by the January 20, 2025, Executive Order titled ‘‘Unleashing American Energy’’ as well as the February 19, 2025, Executive Order titled ‘‘Ensuring Lawful Governance and Implementing the President’s ‘Department of Government Efficiency’ Deregulatory Initiative’’. The intention of these orders was to address the burden unnecessary regulations place on energy affordability, job creation, and national security while also weighing regulatory consistency with the Constitution and “best readings” of authorizing statutes.

In the 2009 Endangerment Finding, EPA concluded that the combination of six greenhouse gases (GHGs) generated by human activity were “air pollution which may reasonably be anticipated both to endanger public health and to endanger public welfare”. In this finding, GHG air pollution was defined as the combination of carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), hydrofluorocarbons (HFCs), Perfluorocarbons (PFCs), and sulfur hexafluoride (SF₆). The determination came as a response to a 2007 Supreme Court Ruling in Massachusetts v. EPA, which dictated that EPA only had the authority to regulate an air pollutant under Section 202(a) of the Clean Air Act (CAA) if it was determined to be an endangerment to public health and welfare. The 2009 rule marked the first time that the threat of global climate change (rather than local or regional exposure endangerment) was referenced as a basis for domestic emissions regulation. Since its finalization, the rule has been relied on in part as the legal basis of all GHG emission standards issued by the EPA over the previous 16 years. 

In this latest NPRM, the EPA proposes to reverse the 2009 Endangerment Finding based on their interpretation that EPA cannot regulate emissions under Section 202(a) unless an air pollutant is found to be a threat to local or regional public health exclusively through local or regional exposure. It states that adversely impacting a subset of regions globally does not adequately meet the standard for regulation. It further argues that Congress’s silence on GHGs in the CAA should be interpreted as a lack of authority to regulate GHG emissions in response to global climate change concerns. Finally, it maintains that the finding’s scientific basis is contradicted by empirical data, studies, and scientific developments since its establishment in 2009, especially because not all of the defined GHG pollutants are emitted from vehicle tailpipes (which is the basis for the original studies).

While the original 2009 Endangerment Finding was made in the context of tailpipe emissions, it had a cascading effect as it became the basis for additional GHG-regulating rules under the CAA. In recognition of those impacts, EPA has initiated or indicated an intent to issue separate rulemakings to address “any overlapping issues.” Under the NPRM, EPA proposed to repeal all GHG tailpipe emission standards for light, medium, and heavy-duty vehicles and engines for model years (MY) 2012 to 2027 and beyond along with the associated electric vehicle mandate. Additionally, the proposed rescission is expected to impact GHG regulations under the New Source Performance Standards (NSPS) standards for carbon dioxide and methane under Clean Air Action Section 111(b) and 111(d); this includes the methane provisions in NSPS Subpart OOOOb and EG OOOOc affecting crude oil and natural gas facilities and the GHG standards for fossil fuel-fired electric generating units (EGUs) in NSPS Subparts TTTT, TTTTa, and UUUUb. Lastly, all other GHG endangerment findings will also be revoked as part of the proposal, including GHG emission standards for aircraft found in 40 CFR Part 87 and Part 1030.

Although the proposed repeal itself will almost certainly face court challenges (most likely by environmental groups and state attorneys), the NPRM is drafted in a manner that could protect industry from Federal common-law claims for GHG emissions if the proposal is finalized. In the 2011 Supreme Court case American Electric Power Co. v. Connecticut, the Court found that EPA action to regulate GHG pollutants under its authority granted by the CAA was sufficient protection against public nuisance claims to address climate change. In order to keep those protections for industry in place, the EPA argues actions of the NPRM create a relaxation of regulatory standards instead of a lack of regulatory action by the agency.

Per the NPRM, the EPA is soliciting comments on all aspects of the proposal, including the proposed legal and scientific developments and any reliance interests regulated parties or additional stakeholders have in the existing GHG standards. The public comment period closes September 21, 2025.

Upcoming State of GHG Regulations

The EPA has already separately proposed the repeal of GHG emission standards for EGUs as well as formally announced the reconsideration of NSPS Subpart OOOOb and EG OOOOc. The EPA’s Green House Gas Reporting Program (GHGRP) codified in 40 CFR Part 98 is not directly impacted by this proposal, as it was created by a congressional directive in 2007. However, the EPA has also announced its formal reconsideration of the Greenhouse Gas Reporting Rule’s general provisions as well as specifically the Subpart W provisions for the oil and natural gas industry.

What You Can Do Now:

If your operations are subject to these rules, you should not assume the requirements will disappear overnight. Regulatory uncertainty is likely to increase in the short-term as legal challenges and the administrative processes play out. During this time, Trinity recommends that companies do the following:

• Review the proposed rules and assess how the changes may impact your compliance obligations, capital planning, and sustainability commitments
• Participate in the public comment process, either on behalf of your organization directly or as part of a trade group or industry coalition
• Monitor state and international-level regulatory developments that may attempt to fill federal regulatory gaps and can impact your supply chain or end markets (e.g., California’s GHG Standards or EU’s Carbon Border Adjustment Mechanism)
• Evaluate existing GHG monitoring, recordkeeping, and reporting practices carefully – keeping cost-effective systems in place can future-proof your operations against the expense of reimplementation and the risk of falling behind evolving regulatory and market expectations

The proposed repeal of the Endangerment Finding signals a fundamental shift in U.S. climate regulation, but the path forward is far from settled. With litigation likely and state or global regulations poised to fill the gap, companies must prepare for uncertainty, not inaction. Trinity Consultants is actively tracking these developments and helping clients assess operational and strategic risks. Our experts can assist with rule interpretation, preparing comments before the September 21 deadline, and evaluating the implications for your reporting, capital planning, and ESG commitments. Contact your local Trinity office to schedule a consultation and stay ahead of this evolving regulatory landscape.