Rescinding the Endangerment Finding
Written by Kelli Cigelnik and Professor Pat Parenteau

I. Introduction: A High-Stakes Reversal

On December 15, 2009, the EPA issued a final ruling on six greenhouse gases (GHGs) that endanger public health and public welfare under Section 202(a) of the Clean Air Act.[1] The EPA also concluded that these combined emissions from motor vehicles contribute to air pollution which endangers public health and welfare under Section 202(a) of the Clean Air Act.[2] This is otherwise known as the Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 202(a) of the Clean Air Act (2009 Endangerment Finding).

On August 1, 2025, Administrator Zeldin and the EPA proposed to rescind the 2009 Endangerment Finding.[3] The rescission of the 2009 Endangerment Finding raises two pivotal legal questions that strike at the foundation of EPA’s authority and responsibility on climate regulation. First, the EPA is signaling it may no longer view GHGs as pollutants within the Clean Air Act’s scope. Second, even if the EPA did have authority to regulate GHGs, regulating U.S. emissions has a negligible global impact.

II. Quick Background: Massachusetts v. EPA and the History of the Finding

The EPA promulgated the 2009 Endangerment Finding in response to the landmark decision in Massachusetts v. EPA.[4] In Massachusetts, the Supreme Court held that greenhouse gases are “air pollutants” under the Clean Air Act.[5] Thus, the EPA has authority under the Clean Air Act to regulate these air pollutants, such as motor vehicle emissions.[6] In addition, the Court explicitly stated that once the EPA makes the Endangerment Finding, it must regulate all sources that cause or contribute to the endangerment and cannot refuse to regulate such sources based on policy reasons outside of the statute.[7]

Following Massachusetts, the EPA conducted an extensive scientific and legal review that culminated in the 2009 Endangerment and Cause or Contribute Finding.[8] In that rulemaking, the agency found that six well-mixed GHGs collectively threaten public health and welfare by driving global climate change, and that emissions from new motor vehicles contribute to this pollution.[9] The Endangerment Finding forms the legal foundation for subsequent federal climate regulations. Every major climate rule since, including vehicle emission standards, power plant performance standards, and stationary source permitting, has relied on the 2009 Endangerment Finding as its statutory predicate.[10] Without it, the EPA’s authority to regulate GHGs under the Clean Air Act would effectively collapse.

III. Was Massachusetts v EPA Wrongly Decided?
a. Zeldin’s Theory

In the Reconsideration of the 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards (Rescission of the Endangerment Finding), the EPA proposes to rescind all GHG emission standards under Section 202(a), stating that it “no longer believes that we have the statutory authority and record basis required to maintain this novel and transformative regulatory program.”[11] It asserts that the Clean Air Act was designed for local and regional air pollution, not for global phenomena like climate change.[12] This interpretation narrows the statutory definition of “air pollutant” by emphasizing that even if GHGs fit within the Clean Air Act-wide definition, the EPA is not required—or even authorized—to regulate them under Section 202(a) absent a clear causal link to local air pollution harms.

Although the proposal stops short of directly overruling Massachusetts, it frames the 2009 Endangerment Finding as inconsistent with the Supreme Court’s later major-questions doctrine cases.[13] In effect, the EPA is inviting a re-examination of Massachusetts’s holding that GHGs are “air pollutants” under the Clean Air Act.[14] Under Zeldin, the EPA now takes the position that there is a geographical limitation on its authority to regulate pollution coming from outside the United States.[15]

Ultimately, the EPA is stressing the historical context: the Clean Air Act has traditionally addressed localized pollutants that cause direct, measurable harm through regional exposure.[16] This is unlike GHGs, which operate on a global scale. Further, the EPA claims that analyzing global climate effects under Section 202(a) exceeds the intelligible principle required for delegation, suggesting that Congress never meant the statute to encompass GHGs at all.[17]

b. Legal Obstacles

Despite the EPA’s attempt to reinterpret its authority, Massachusetts remains binding precedent. Only the Supreme Court can overturn that ruling, which squarely held that greenhouse gases qualify as “air pollutants” under the Clean Air Act.[18] Therefore, as long as Massachusetts stands, the EPA cannot unilaterally declare that GHGs fall outside the Clean Air Act’s scope.

Furthermore, the Clean Air Act’s text is written in deliberately broad terms. Section 302(g) defines “air pollutant” expansively as “any air pollution agent or combination of such agents,” a definition that comfortably encompasses carbon dioxide and other greenhouse gases.[19] Even if the EPA advances a narrower interpretation of Section 202(a), courts will likely view that reading as inconsistent with both statutory text and controlling precedent.[20]

Under the Supreme Court’s State Farm decision, the EPA’s authority to rescind a prior finding is not unlimited. The agency must acknowledge its change in position, offer a “reasoned explanation,” and demonstrate that the prior interpretation was legally or factually flawed.[21] The current proposal cites “new legal and scientific developments” and shifting policy priorities, but these justifications appear largely ideological rather than evidentiary.[22]

Comments from organizations such as the Natural Resources Defense Council (NRDC) have emphasized that the EPA has not presented robust new scientific evidence to undermine the 2009 Endangerment Finding’s conclusions.[23] Instead, the agency questions the reliability of prior assessments while acknowledging ongoing uncertainties.[24] Without concrete data demonstrating that the earlier record was erroneous or unworkable, a rescission would likely be deemed “arbitrary and capricious” under the Administrative Procedure Act.[25] In short, the EPA faces substantial legal barriers to reversing course without a fresh factual foundation or a change in the governing law.

c. Broader Implications

A rescission of the 2009 Endangerment Finding would constitute a fundamental retraction of federal authority over GHG regulation. By asserting that GHGs fall outside the scope of the Clean Air Act, the EPA would remove the major statutory authority for reducing the emissions that are driving climate change. Such a position would create a regulatory void, displacing federal uniformity with a fragmented system of state-level initiatives and inconsistent standards. If the Supreme Court were to agree with this new interpretation and either reverse or modify Massachusetts it would mean that future administrations could not revive the regulations without congressional action.

Beyond constitutional limits, the reversal would destabilize longstanding reliance interests. Industry actors, states, and environmental organizations have structured regulatory frameworks and investments on the expectation of continued federal oversight. Abrupt withdrawal would erode those expectations and diminish regulatory coherence.

IV. Can EPA Decline to Regulate Emissions it Considers Insignificant on a Global Scale?
a. The De Minimis Argument

Even if the EPA were to concede that it retains statutory authority under Massachusetts, Administrator Zeldin’s proposal argues that regulating GHG emissions would have an inconsequential effect on global climate outcomes.[26] Under this theory, U.S. emissions represent too small a fraction of total global output to warrant costly domestic regulation.[27] The agency thus characterizes GHG regulation as de minimis—a trivial exercise unlikely to produce meaningful environmental benefits.

Zeldin frames this rationale as a pragmatic and economically responsible approach. By his account, Congress did not design the Clean Air Act to impose significant costs on American industries for symbolic or negligible global gains.[28] Instead, the EPA claims that effective climate action requires multilateral coordination beyond the Clean Air Act’s jurisdictional reach.[29] In policy terms, the proposal recasts climate regulation as a matter of foreign affairs and international competitiveness, rather than environmental protection per se.

b. The Legal Problem

The Clean Air Act does not contain a de minimis exception to regulation of emissions that “may reasonably be anticipated to endanger public health or welfare.”[30] Once that determination is made, the Clean Air Act obligates the EPA to regulate; it does not permit the agency to weigh other policy considerations or cost-effectiveness of its actions in deciding whether regulation is warranted.[31]

The Supreme Court has repeatedly rejected attempts by agencies to read economic or policy discretion into clear statutory commands. In Whitman v. American Trucking Associations, the Court held that the EPA may not consider cost in setting National Ambient Air Quality Standards, emphasizing that where Congress speaks in mandatory public health terms, policy tradeoffs are foreclosed.[32] The Massachusetts decision further reinforced that the EPA cannot decline to regulate based on a policy judgment “divorced from the statutory text.”[33] The Court explicitly rejected the argument that EPA could consider the need for international cooperation as a reason not to regulate domestic emissions.[34]

By invoking a de minimis rationale, the EPA effectively reintroduces policy discretion that Congress and the courts have explicitly denied. Even if U.S. emissions represent a small portion of global totals, the statute requires regulation once an endangerment finding exists.[35] The Clean Air Act is built on cumulative control: local, sectoral, and incremental actions that collectively reduce overall pollution burdens.[36] To decline regulation on the ground that the problem is global is to nullify the Clean Air Act’s preventive purpose.

The proposal’s factual premise is equally flawed. While U.S. emissions account for roughly 13% of global totals, they remain the second-largest national source of greenhouse gases.[37] Regulatory rollback by such a major emitter undermines international climate cooperation and slows technological progress across industries. Moreover, because atmospheric GHGs are well-mixed globally, emissions reductions in any one country have measurable, albeit distributed, impacts on global concentrations.[38] Dismissing U.S. actions as insignificant ignores this cumulative effect and discounts the leadership role historically played by the U.S. in driving global standards.

The EPA’s reasoning also conflicts with its own prior findings. The 2009 Endangerment Finding, supported by extensive peer-reviewed research, recognized that global climate change is a collective-action problem that requires incremental domestic steps.[39] To now claim that individual contributions are “too small to matter” not only contradicts that scientific consensus but also violates the principle that agencies must provide a reasoned explanation when departing from prior determinations.

c. Paradigm Shift

The de minimis approach represents more than a statutory reinterpretation; it reflects a philosophical shift from prevention to abdication. Congress designed the Clean Air Act as a forward-looking statute—its thresholds are intentionally protective, operating before harm becomes irreversible. Decades ago, the D.C. Circuit Court of Appeals affirmed the EPA’s authority to regulate based on a precautionary standard, holding that the EPA could act when there was a “significant risk of harm” even without absolute scientific certainty.[40] By redefining the statute as ineffectual-by-design, the EPA transforms a preventive framework into a reactive one. This shift signals a retreat from science-based policymaking and an embrace of political convenience disguised as statutory fidelity.

Critics, including environmental organizations and several state attorney generals, argue that the EPA’s reasoning mirrors broader efforts to delegitimize environmental governance under the “major questions” doctrine.[41] This would transform every significant regulatory initiative into a presumptive overreach contrary to the Court’s admonition that the major question doctrine was to be used in “extraordinary cases.”[42] In doing so, the agency risks hollowing out the very administrative capacity Congress created to address emerging environmental harms.

V. Procedural Vulnerabilities

Beyond its substantive weaknesses, the rescission proposal is procedurally vulnerable. Under the State Farm standard, agencies must provide a reasoned explanation for any change in policy and support that shift with evidence showing that the prior determination was either erroneous or unworkable.[43] Here, the EPA offers neither.

The proposal lacks a comprehensive Regulatory Impact Analysis or any comparable peer-reviewed assessment demonstrating that prior findings were invalid. The agency relies instead on vague references to “new legal and scientific developments” without citing any concrete data or authoritative studies that contradict the 2009 record.[44] This omission is critical: because the original finding rested on extensive scientific consensus and interagency review, rescission requires an equally rigorous evidentiary showing.

For its challenge to the robust scientific evidence supporting the 2009 Endangerment Finding the proposal relies on a report produced by the Climate Working Group consisting of five scientists hand-picked by Christopher Wright, the Secretary of Energy, and widely regarded as climate skeptics.[45] In a decision by the US District Court for Massachusetts, Senior Judge Wiliam Young ruled that group was likely formed in violation of the Federal Advisory Committee Act, a ruling that the Department of Justice has chosen not to appeal.[46] Judge Young subsequently ordered the government to produce all of the records relating to the work of the Climate Working Group, and reserved judgment on whether EPA should be prohibited from considering the group’s report.[47]

Moreover, the absence of an independent Science Advisory Board review—customary for major environmental rulemakings—further undermines the rule’s legitimacy.[48] The proposal’s procedural shortcuts signal a foregone policy conclusion rather than a genuine reevaluation.

Legal challenges are inevitable. Under Section 307(b) of the Clean Air Act, all petitions for review of nationally applicable EPA actions are filed directly in the D.C. Circuit.[49] The D.C. Circuit has historically applied State Farm’s “hard look” review with particular rigor in environmental cases.[50] Plaintiffs such as the NRDC, Environmental Defense Fund, and several states (including California and New York) are likely to argue the rescission is both arbitrary and capricious and contrary to law.[51]

If the court agrees, it could vacate the rescission and remand the rule to the agency, which would potentially reinstate the 2009 Endangerment Finding by default. Such a decision would reaffirm the procedural guardrails that prevent agencies from overturning major regulatory frameworks on ideological grounds.

VI. What’s at Stake
a. Immediate Regulatory Consequences

Once finalized, the rescission of the 2009 Endangerment Finding would immediately nullify the EPA’s authority to regulate greenhouse gas emissions from motor vehicles—the so-called “tailpipe rules.”[52] Emissions from powerplants and vehicles account for over half of total GHG emissions in the U.S.[53] These rules have driven the largest reductions in GHG emissions of any federal program, providing the legal and policy foundation for both mobile and stationary source controls.[54] Their repeal would also set the stage for invalidating power plant performance standards under Section 111 of the Clean Air Act.[55] Together, vehicle and power plant regulations cover more than half of total U.S. emissions.[56] The collapse of these programs would therefore represent a structural dismantling of the nation’s core climate policy architecture.

The loss of the Endangerment Finding would also unravel the broader regulatory ecosystem built upon it. Agencies, states, and private actors have invested in compliance frameworks, emissions tracking systems, and renewable energy markets on the assumption of ongoing federal oversight.[57] Its rescission would create a legal vacuum by displacing federal uniformity with a patchwork of state-level initiatives and voluntary corporate programs. This fragmentation would undermine predictability and increase litigation risk for industry, while diminishing overall climate progress.

b. Long-Term Legal Ramifications

Should the Supreme Court affirm that the EPA lacks authority to regulate GHGs under the Clean Air Act, the consequences would extend beyond current rulemakings. A future administration could not simply reinstate the Endangerment Finding or adopt analogous regulations without new congressional authorization.[58] Such a ruling would therefore codify a permanent limitation on federal climate authority, reshaping environmental law for decades.

The decision would also reverberate through the expanding field of climate liability litigation. Oil and gas companies currently argue that federal law preempts state-law tort claims under the displacement doctrine recognized in American Electric Power v. Connecticut.[59] If the EPA now disclaims authority to regulate GHGs, those preemption arguments would collapse, potentially reviving federal common law and strengthening state and municipal claims for climate damages. In short, the rescission could simultaneously erode federal regulatory capacity while exposing industry to expanded judicial liability.

c. Broader Constitutional Implications

At a constitutional level, the rescission tests the limits of executive power to reinterpret long-standing statutory mandates.[60] By rejecting the 2009 Finding without a change in law or fact, the EPA would effectively amend the scope of the Clean Air Act through administrative fiat.[61] This raises profound separation-of-powers concerns: whether an agency may nullify judicial precedent and statutory purpose by mere reinterpretation.[62] The outcome of ensuing litigation will thus define the balance between political discretion and legal constraint within the administrative state.

VII. Conclusion

The proposed rescission of the Endangerment Finding is far more than a policy reversal. It is a constitutional and scientific reckoning. It challenges the resilience of statutory interpretation, the legitimacy of evidence-based rulemaking, and the integrity of the administrative process itself. If courts uphold the rescission, the EPA’s capacity to address climate change under existing law will evaporate, leaving regulation to the fragmented discretion of states and private markets. The Clean Air Act’s role as a comprehensive framework for national air quality protection would be irreparably narrowed.

If, however, the courts reject the rescission, the ruling would reaffirm that administrative agencies cannot discard binding precedent or established science to suit transient political agendas. Upholding Massachusetts v. EPA  would preserve the principle that evidence, not ideology, governs environmental law. It would confirm that the Clean Air Act’s broad language and preventive purpose remain vital tools for addressing modern environmental crises.

Ultimately, the fate of the 2009 Endangerment Finding will shape not only the trajectory of U.S. climate policy but also the boundaries of lawful governance in an era where global problems demand enduring legal commitments.

Author Bio:
Kelli Cigelnik is a dual Juris Doctorate and Masters of Climate and Environmental Policy student at Vermont Law and Graduate School. She serves as Editor-in-Chief for Vermont Law Review Vol. 50 and Vermont Journal of Environmental Law Vol. 27. Kelli went to undergraduate at the University of Illinois at Urbana-Champaign, receiving degrees in Integrative Biology and Political Science, with a minor in Earth, Society, and Environmental Sustainability and a concentration in Civic Engagement. She has always been fascinated with how the biological sciences interacts with law and policy. Kelli spent last summer working at the Office of the Illinois Attorney General in its Environmental Bureau. She hopes to continue this work in the environmental sphere after graduation from VLGS.

[1] Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 202(a) of the Clean Air Act, 74 Fed. Reg. 66,496 (Dec. 15, 2009).

[2] Id.

[3] Reconsideration of 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards, 90 Fed. Reg. 36,288 (proposed Aug. 1, 2025).

[4] 549 U.S. 497 (2007).

[5] Id. at 532.

[6] Id.

[7] Id. at 534.

[8] Greenhouse Gas Endangerment Finding Timeline, U.S. Env’t Prot. Agency, https://www.epa.gov/climate-change/greenhouse-gas-endangerment-finding-timeline (last updated Oct. 8, 2025).

[9] Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 202(a) of the Clean Air Act, 74 Fed. Reg. 66,496 (Dec. 15, 2009). The six gases are: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride. The EPA found that these gases are “well mixed” in the atmosphere meaning their concentration is roughly the same everywhere, regardless of where they were emitted, and they collectively contribute to climate change.

[10] See id. at 66,538; Reconsideration of the Endangerment Finding and Greenhouse Gas Vehicle Standards, 90 Fed. Reg. 36,299, 36,306 (Aug. 1, 2025).

[11] Reconsideration of 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards, 90 Fed. Reg. 36,288, 36,298 (proposed Aug. 1, 2025).

[12] Id.

[13] Id. at 36,305; See, e.g., West Virginia v. EPA, 142 S. Ct. 2587, 2609 (2022) (holding that Congress did not grant the EPA in Section 111(d) of the Clean Air Act the authority to set emission caps based on shifting generation from fossil fuels to renewables); King v. Burwell, 576 U.S. 473, 485-86 (2015) (involving a question of deep “economic and political significance”); Util. Air Regul. Grp. v. EPA, 473 U.S. 302, 324 (2014) (noting that Congress should “speak clearly if it wishes to assign to an agency decisions of vast ‘economic and political significance’” (quoting FDA v. Brown & Williamson Tobacco Corp., 529 U.S. 120, 160 (2000)).

[14] Massachusetts v. EPA, 549 U.S. 497, 532 (2007).

[15] Reconsideration of 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards, 90 Fed. Reg. 36,288, 36312 (proposed Aug. 1, 2025) (stating that “[t]he CAA does not authorize the EPA to regulate international sources of emissions”).

[16] Id. at 36,301.

[17] Id.

[18] Massachusetts, 549 U.S. at 532.

[19] 42 U.S.C. § 7602(g).

[20] Id.

[21] See Motor Vehicle Mfrs. Ass’n v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29, 57 (1983) (holding that an agency must provide a “reasoned analysis” for changing its decision on a regulation); FCC v. Fox Television Stations, 556 U.S. 502, 515 (2009) (explaining that an agency need only merely prove that its new policy is “permissible” and that there are good reasons for it).

[22] Reconsideration of 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards, 90 Fed. Reg. 36,288, 36,296 (proposed Aug. 1, 2025); see Memorandum from Lee Zeldin, Administrator, Environmental Protection Agency, to Russell Vought, Director, Office of Management and Budget (Feb. 19, 2025).

[23] See NRDC, Comments on Reconsideration of 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards, 90 Fed. Reg. 36,288 (proposed Aug. 1, 2025).

[24] Reconsideration of 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards, 90 Fed. Reg. 36,288, 36,299 (proposed Aug. 1, 2025).

[25] 5 U.S.C. § 706(2)(A).

[26] Reconsideration of 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards, 90 Fed. Reg. 36,288, 36,304 (proposed Aug. 1, 2025).

[27] Id. at 36,304, 36,311.

[28] Id. at 36,311.

[29] Id. at 36,301-02, 36,299.

[30] 42 U.S.C. § 7521(a)(1).

[31] See id.; Massachusetts v. EPA, 549 U.S. 497, 533 (2007) (“Under the clear terms of the Clean Air Act, EPA can avoid taking further action only if it determines that greenhouse gases do not contribute to climate change or if it provides some reasonable explanation as to why it cannot or will not exercise its discretion to determine whether they do.”); see also Whitman v. Am. Trucking Ass’ns, 531 U.S. 457, 465–71 (2001) (reinforcing the idea that the EPA cannot consider cost when setting standards under the Clean Air Act unless Congress explicitly authorizes it); Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 202(a) of the Clean Air Act, 74 Fed. Reg. 66,496, 66,507 (Dec. 15, 2009).

[32] Whitman, 531 U.S. at 465–71.

[33] Massachusetts, 549 U.S. at 532.

[34] Id. at 523–25, 526.

[35] Id. at 532–33.

[36] 42 U.S.C. §§ 7401(a)(3)–(4), 7401(b)(1).

[37] See Pierre Friedlingstein et al., Global Carbon Budget 2023, 15 Earth Sys. Sci. Data 5301, 5304-05 (2023); Hannah Ritchie et al., CO₂ and Greenhouse Gas Emissions: United States: CO2 Country Profile, Our World in Data, https://ourworldindata.org/co2/country/united-states (last visited Dec. 7, 2025).

[38] Hannah Ritchie et al., CO₂ and Greenhouse Gas Emissions: United States: CO2 Country Profile, Our World in Data, https://ourworldindata.org/co2/country/united-states (last visited Dec. 7, 2025).

[39] Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 202(a) of the Clean Air Act, 74 Fed. Reg. 66,496, 66, 543 (Dec. 15, 2009).

[40] Ethyl Corp. v. EPA, 541 F.2d 1, 23–24 (D.C. Cir. 1976).

[41] NRDC, Comments on Reconsideration of 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards, 90 Fed. Reg. 36,288 (proposed Aug. 1, 2025), at 50–51, 61, 74 (arguing the EPA’s invocation of the major questions doctrine distorts the separation of powers and undermines congressional and judicially affirmed environmental authority).

[42] West Virginia v. EPA, 142 S. Ct. 2587, 2608, 2609 (2022).

[43] Motor Vehicle Mfrs. Ass’n v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29, 42 (1983) (“[A]n agency changing its course by rescinding a rule is obligated to supply a reasoned analysis for the change beyond that which may be required when an agency does not act in the first instance.”); Id. at 43 (describing the “hard look” doctrine).

[44] Reconsideration of 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards, 90 Fed. Reg. 36,288, 36,310 (proposed Aug. 1, 2025) (claiming “ongoing uncertainties in relevant scientific data and analyses”). The EPA briefly references a “Draft Regulatory Impact Analysis” (EPA-420-D-25-002, July 2025) but provides no substantive discussion or findings from it within the rulemaking record itself. Id. at 36,326. This superficial mention contrasts sharply with the extensive cost-benefit and peer-review documentation that accompanied the 2009 Endangerment Finding. The Draft Regulatory Impact Analysis is a brief, roughly 30-page document, which is far shorter than the hundreds of pages typical of a substantive EPA regulatory impact analysis, such as the 2009 Endangerment Finding’s 200-plus-page Technical Support Document. It includes no quantified estimates of costs or benefits, no sensitivity or uncertainty analysis, and no modeling of the economic, health, or environmental consequences of rescission. Lacking peer-reviewed sources or interagency review, it largely reiterates the policy rationale already presented in the Federal Register notice. In short, the document is procedural and narrative rather than a genuine, data-driven economic or scientific analysis. Compare U.S. Env’t Prot. Agency, Draft Regulatory Impact Analysis for the Reconsideration of the Endangerment Finding (EPA-420-D-25-003, July 2025) with U.S. Env’t Prot. Agency, Technical Support Document for Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 202(a) of the Clean Air Act (EPA-HQ-OAR-2009-0171, Dec. 7, 2009). The EPA will have to rely on a final Regulatory Impact Analysis before issuing a final ruling on rescinding the endangerment finding. The final Regulatory Impact Analysis must still contain data-driven economic and scientific analysis.

[45] A Critical Review of Impacts of Greenhouse Gas Emissions on the U.S. Climate, Dep’t of Energy (2025). The National Academy of Scientists issued a scathing critique of this report and concluded that “the evidence for current and future harm to human health and welfare created by human-caused greenhouse gases is beyond scientific dispute.” Effects of Human-Caused Greenhouse Gas Emissions on U.S. Climate, Health, and Welfare, Nat’l Academies of Scis., Eng’g, and Med. (2025).

[46] Env’t Def. Fund, Inc. v. Wright, 1:25-cv-12249-WGY (D. MA. Sep. 17, 2025).

[47] See Lesley Clark, Judge Orders DOE to Release Records on Climate Working Group, Politico: E&E News (Dec. 9, 2025), https://www.eenews.net/articles/judge-orders-doe-to-release-records-on-climate-working-group/.

[48] Reconsideration of 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards, 90 Fed. Reg. 36,288, 36,296 (proposed Aug. 1, 2025).

[49] 42 U.S.C. § 7607(b)(1).

[50] State Farm, 463 U.S. at 43.

[51] See 5 U.S.C. § 706 (laying out the scope of review for the Administrative Procedure Act).

[52] Reconsideration of 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards, 90 Fed. Reg. 36,288, 36,298 (proposed Aug. 1, 2025); 42 U.S.C. § 7521(a)(1).

[53] What Are the Main Sources of US Greenhouse Gas Emissions?, USAFacts: Env’t, https://usafacts.org/articles/what-are-the-main-sources-of-us-greenhouse-gas-emissions/ (last updated Oct. 1, 2025).

[54] See U.S. Env’t Prot. Agency, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2022, at 2-13, ES-6 (Apr. 2024); see also Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 202(a) of the Clean Air Act, 74 Fed. Reg. 66,496, 66,517 (Dec. 15, 2009); Carbon Pollution Emission Guidelines for Existing Stationary Sources: Electric Utility Generating Units (Clean Power Plan), 80 Fed. Reg. 64,662, 64,672 (Aug. 3, 2015).

[55] Reconsideration of 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards, 90 Fed. Reg. 36,288, 36,298 (proposed Aug. 1, 2025).

[56] See U.S. Env’t Prot. Agency, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2022, at ES-6 (Apr. 2024) (showing that transportation accounted for 37.4% of CO2 emissions from fossil fuel combustion and that industrial CO2 emissions accounted for 26.3% of CO2 emissions from fossil fuel combustion).

[57] See Andrew S. Coghlan, Cong. Rsch. Serv., LSB11320, EPA To Revisit Greenhouse Gas Endangerment Finding 1 (2025).

[58] See id.; see also Greenhouse Gas Endangerment Finding, Env’t & Energy L. Program, Harv. L. Sch., https://eelp.law.harvard.edu/tracker/greenhouse-gas-endangerment-finding/ (last updated Sept. 17, 2025).

[59] 564 U.S. 410, 423 (2011).

[60] Motor Vehicle Mfrs. Ass’n v. State Farm, 463 U.S. 29, 42–44 (1983) (explaining that an agency must supply a reasoned explanation for rescinding prior policy); FCC v. Fox Television Stations, Inc., 556 U.S. 502, 515–16 (2009) (acknowledging that changing course requires acknowledging and justifying the change).

[61] Util. Air Regul. Grp. v. EPA, 573 U.S. 302, 324 (2014) (“We expect Congress to speak clearly if it wishes to assign to an agency decisions of vast ‘economic and political significance.’” (quoting FDA v. Brown & Williamson Tobacco Corp., 529 U.S. 120, 160 (2000)); Massachusetts v. EPA, 549 U.S. 497, 528-35 & n.26 (2007) (rejecting Chevron deference because the statute is clear that GHGs are “air pollutants”).

[62] West Virginia v. EPA, 142 S. Ct. 2587, 2609–11 (2022) (describing how clear-statement rules protects separation of powers where agencies claim transformative authority).