On February 12, 2026, the Trump administration revoked the EPA's 2009 “endangerment finding,” the determination that greenhouse gases may reasonably be anticipated to endanger public health and welfare. EPA Administrator Lee Zeldin called it “the single largest deregulatory action in U.S. history.”
What the action does, precisely, is narrower than much of the coverage suggested, and the precise version is still large. The 2009 finding was made under Clean Air Act Section 202(a), which governs motor vehicles. Rescinding it eliminated the finding and every federal greenhouse gas standard for vehicles and engines from model year 2012 forward, along with the off-cycle credits including the one for automatic start-stop. The EPA put the savings at more than $1.3 trillion, about $2,400 per vehicle.
It did not by itself repeal power plant rules, which rest on a different section of the Act, and it did not touch regulation of conventional pollutants such as ozone and nitrogen oxides. What it does is remove the legal foundation that federal greenhouse gas regulation has been built on since 2009, which is why reporting described it as potentially unleashing a broader undoing of climate rules for stationary sources. That broader effect depends on further rulemaking and on the courts.
The finding followed the Supreme Court's 2007 ruling in Massachusetts v. EPA, which held that greenhouse gases are air pollutants under the Clean Air Act and that the agency had to determine whether they endanger public health. In December 2009 the EPA concluded that six greenhouse gases do.
The EPA's legal argument for reversing course is that Section 202(a) covers “air pollution” in a local and regional sense and not global phenomena. In the agency's words, that section “does not provide EPA statutory authority to prescribe motor vehicle emission standards for the purpose of addressing global climate change concerns.” It added that American vehicle standards cannot materially affect global climate, making them futile. The EPA did not publish a technical support document with the rescission; the 2009 finding came with one.
Legal scholars at Harvard Law School's environmental policy program note that Massachusetts v. EPA already considered and rejected a version of the “not air pollution” reading, that the statute requires the agency to decide the question on scientific judgment without weighing cost, and that Congress has declined to strip the EPA of this authority in the seventeen years since.
Two challenges are pending in the U.S. Court of Appeals for the D.C. Circuit. On February 18, 2026, a coalition including the American Public Health Association, the American Lung Association, Physicians for Social Responsibility, the Union of Concerned Scientists, the Natural Resources Defense Council, Environmental Defense Fund and the Sierra Club filed suit. On March 20, two dozen states along with more than a dozen cities and counties filed their own.