From Executive Summary

In this action, the EPA proposes to rescind all greenhouse gas (GHG) emission standards for light-duty, medium-duty, and heavy-duty vehicles and engines under CAA section 202(a). Upon review of the underlying actions and intervening legal and scientific developments, including recent decisions by the U.S. Supreme Court and the scientific information summarized in this preamble, the EPA no longer believes that we have the statutory authority and record basis required to maintain this novel and transformative regulatory program. We seek comment on all aspects of this proposal, including on the legal and scientific developments that are being subject to public comment for the first time in this rulemaking.

The EPA now proposes to rescind the Endangerment Finding and all resulting GHG emission standards for new motor vehicles and engines, including the light-duty, medium-duty, and heavy-duty vehicle and engine standards for model years (MY) 2012 to 2027 and beyond. The remainder of this section describes the need for regulatory action and the scope of the proposed action, including rescission of the Endangerment Finding, repeal of related GHG emission standards, and minor conforming adjustments to unrelated emission standards for new motor vehicles and engines that we are not proposing to alter as part of this rulemaking.

Section II of this preamble sets out relevant background, including the events leading up to the Endangerment Finding, the approach taken in the Endangerment Finding to analyzing the scientific record, and the regulations issued since 2009 in reliance on the Endangerment Finding. We also summarize the premises, assumptions, and conclusions in the Endangerment Finding and the scientific information, including empirical data, peer-reviewed studies, and real-world developments since 2009 that led the Administrator to develop concerns sufficient to initiate reconsideration of the ongoing validity and reliability of the Endangerment Finding.

Section III of this preamble describes our legal authority to rescind the Endangerment Finding and repeal the resulting GHG standards issued under CAA section 202(a). Because this proposed action would not impact fuel economy standards and emission standards for criteria pollutants and hazardous air pollutants regulated under the CAA, we explain the relationship between these regulations to set the outer bounds of amendments at issue in this rulemaking.

Section IV.A of this preamble describes our proposal to rescind these prior actions because the Endangerment Finding exceeded our statutory authority under CAA section 202(a). As explained further below, we propose that the term “air pollution” as used in CAA section 202(a) is best read in context as referring to local or regional exposure to dangerous air pollution, consistent with our longstanding practice before 2009. We further propose that CAA section 202(a) does not grant the Administrator “procedural discretion” to issue standalone findings that trigger a duty to regulate, or, conversely, to prescribe standards, without making the requisite findings for the particular air pollutant emissions and class or classes of new motor vehicles or engines at issue. We also propose that CAA section 202(a) does not authorize the Administrator to make separate findings for endangerment and causation or contribution. Rather, we propose that CAA section 202(a) requires the Administrator to find that the relevant air pollutant emissions from the class or classes of new motor vehicles or engines at issue cause, or contribute to, air pollution which endangers public health or welfare, without relying on emissions from stationary or other sources regulated by distinct CAA provisions. As the Supreme Court made clear in Loper Bright Enterprises v. Raimondo, 603 U.S. 369 (2024), we can no longer rely on statutory silence or ambiguity to expand our regulatory power. And because the Nation’s response to global climate change concerns is an issue of significant importance that Congress did not clearly address in CAA section 202(a), we propose that the major questions doctrine further reinforces and provides an additional basis for our proposed interpretations and actions.

The Agency did not have the benefit of the Court’s decisions in Loper Bright and West Virginia, among other applicable precedents, when issuing the Endangerment Finding in 2009. Finally, we explain that the EPA reached contrary conclusions in the Endangerment Finding by misconstruing the Supreme Court’s decision in Massachusetts v. EPA, 549 U.S. 497 (2007), which vacated our denial of a petition for rulemaking on distinct grounds. Read on its own terms, Massachusetts did not require the Agency to find that GHGs are subject to regulation under CAA section 202(a) and does not support our implementation of the statute since 2009.

The Administrator’s review of the relevant information, including scientific literature, gave rise to serious concerns that our actions taken to regulate GHG emissions from new motor vehicles and engines exceed our statutory authority under CAA section 202(a) and are otherwise inappropriate. Continuing to impose billions of dollars in regulatory costs on American businesses and consumers without an adequate legal basis would threaten to undermine public confidence in our activities and commitment to fulfilling the Agency’s core mission: protecting human health and the environment. The EPA has expended significant resources implementing the GHG regulatory program for mobile sources and attempting to expand its GHG regulatory program to stationary sources with limited success in the courts and no apparent real-world results, often at the expense of programs that fall squarely within our statutory authority. Prompt action is needed to address these concerns with the benefit of public participation.

Relatedly, the Administrator has serious concerns that many of the scientific underpinnings of the Endangerment Finding are materially weaker than previously believed and contradicted by empirical data, peer-reviewed studies, and scientific developments since 2009. This proposal seeks public comment on these developments for the first time. Prompt action is needed to address these concerns, and the Administrator requests stakeholder input on the continuing vitality of the assumptions, predictions, and conclusions animating the Endangerment Finding.