Current Status
On Aug. 1, 2025, EPA proposed rescinding its 2009 Endangerment Finding — its conclusion that greenhouse gas emissions are air pollutants under the Clean Air Act that contribute to pollution that endangers public health or welfare. If finalized, EPA’s regulation of greenhouse gas emissions from US vehicles and other sectors will end.
Why It Matters
The Endangerment Finding, issued in 2009, forms the basis of greenhouse gas regulation in the United States. EPA’s current proposal directly addresses emission from US vehicles, but EPA has made analogous findings for other sectors (new and existing fossil fuel-fired power plants and oil and gas facilities) that are also major GHG emitters in the US. If EPA finalizes its current proposal to rescind the Endangerment Finding, the agency will no longer regulate GHG emissions from US vehicles and will almost certainly rescind GHG emissions regulations from other sectors for the same reason.
If EPA rescinds the Endangerment Finding based on its primary rationale — that it lacks authority to regulate GHG emissions under the Clean Air Act — and courts endorse that view in the litigation we expect would follow, future administrations would be prevented from regulating GHGs under the Act.
Rescinding the Endangerment Finding based on a narrow reading of EPA’s authority under the Clean Air Act could open the door to common law nuisance suits against industry. States may also seek to fill a regulatory void if EPA fails to regulate GHG emissions.
Key Resources
Timeline
Dec. 8, 2025 The district court ruled during a hearing that the Department of Energy must release the Climate Working Group’s records in accordance with the Federal Advisory Committee Act. Env’t Def. Fund v. Wright, No. 1:25-cv-12249 (D. Mass.).
Sept. 17, 2025 The district court granted-in-part the environmental groups’ motion for summary judgment, holding that the Climate Working Group was not exempt from the Federal Advisory Committee Act as defendants had argued. The court also denied the environmental groups’ motion for a preliminary injunction, finding that they had not demonstrated irreparable injury from the Climate Working Group’s withholding of records. Env’t Def. Fund v. Wright, No. 1:25-cv-12249 (D. Mass.).
Aug. 15, 2025 EPA extended the comment period for its proposal to rescind the Endangerment Finding. Comments are now due Sept. 22, 2025.
Aug. 12, 2025 Two environmental groups filed a lawsuit challenging the Department of Energy’s formation of a Climate Working Group in early 2025. The group is comprised of five outside scientists who the agency engaged to provide “a critical assessment of the conventional narrative on climate change.” EPA relied on the report in reaching its proposed conclusion that climate science is too uncertain to conclude that GHG emissions from US vehicles contributes endangerment of public health or welfare. The lawsuit filed by Environmental Defense Fund and Union of Concerned Scientists alleges that establishment and use of the Climate Working Group violated the Federal Advisory Committee Act because the group is an advisory committee under that statute and failed to comply with several its requirements. Env’t Def. Fund v. Wright, No. 1:25-cv-12249 (D. Mass. Aug. 12, 2025).
Aug. 1, 2025 EPA issued a proposal to rescind the Endangerment Finding —EPA’s longstanding scientific conclusion upon which EPA’s regulation of greenhouse gas (GHG) emissions rests — and all GHG standards for light, medium, and heavy-duty vehicles. EPA argues that it lacks authority under the Clean Air Act to regulate pollutants that do not have immediate and direct local or regional effects, that emissions from US vehicles are too small to endanger public health or welfare, and that it must rescind the Endangerment Finding because regulating vehicle emissions is costly and futile. EPA also argues that science about climate change causes and effect is too uncertain to warrant the Endangerment Finding. EPA includes an alternative proposal to rescind all GHG vehicle standards even if the Endangerment Finding remains in place. Comments are due by Sept. 15, 2025.
Dec. 15, 2009 EPA issued an Endangerment Finding under Clean Air Act Section 202(a), concluding that six GHGs — carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) — are air pollutants that endanger public health and welfare. EPA issued the Endangerment Finding after the Supreme Court rejected the agency’s prior refusal to do so for reasons not grounded in science, in Massachusetts v. EPA, 549 U.S. 487 (2007). The finding underpins EPA’s regulation of GHGs, including vehicle emissions standards, methane rules, and power plant regulations.