April 12, 2026
The Environmental Protection Agency (EPA) is spreading false or misleading statements about dangerous greenhouse gases to justify its recent refusal to regulate them. Through a rollout of precarious legal interpretations, alternative science, and cherry-picked consumer data, EPA has built a large body of counter-information to support actions that could spur increased community devastation from climate change and ultimately drive up vehicle-related costs for consumers. This three-part blog series aims to demystify EPA’s convoluted reasoning for terminating the Endangerment Finding and help readers better understand:
- PART 1: What the Endangerment Finding is and why it matters.
- PART 1: The legal arguments that the Trump administration’s EPA is making to rescind the finding, and why they are weak.
- PART 2: The scientific rationale behind the decision and why the majority of the scientific community rejects it.
- PART 3: The promised economic benefits that EPA claims rescission will spark, and why it will likely bring the opposite.
The EPA rescinded its own determination
On February 12, 2026, the Trump administration overturned a landmark determination designed to reduce greenhouse gas emissions and slow climate change. The determination, known as the Endangerment Finding, is a scientific determination that greenhouse gases like carbon dioxide (CO2) and methane harm (or: literally endanger) human health and welfare. Released by the EPA in 2009, and based on sound science, it legally obligated the EPA to regulate greenhouse gases. The Trump administration now faces numerous court challenges for rescinding the finding, but for now, they have scratched it from the record, giving way for increased air pollution, accelerated climate change, and worsening natural disasters.
Since early 2025, EPA’s new Trump-appointed Administrator, Lee Zeldin, has toured media outlets to stoke uncertainty around the Endangerment Finding. A string of theoretical legal interpretations, some alternative takes on climate science, and big promises to save to consumers and car manufacturers money through deregulation have been Administrator Zeldin’s most-sited reasons for reneging on EPA’s regulatory duties. And for those not familiar with the scientific and legal substance that the Endangerment Finding is based upon, Administrator Zeldin’s arguments might at first seem fleshed out enough to hold some water. But while the agency has published hundreds of pages intended to explain its actions, at close examination, those documents do a poor job of explaining how rescinding the finding will do anything but worsen the state of public welfare.
What is the Endangerment Finding, and how did it come to be?
The Endangerment Finding ultimately resulted from a 1970 amendment to the Clean Air Act (CAA). This amendment, known as section 202(a), gave the EPA authority to set emission standards for new motor vehicles or engines to control air pollutants that endanger public health or welfare. Prior to 2007, greenhouse gases (GHGs) were not formally recognized as air pollutants. This is in part because even though the greenhouse effect had been documented, the question of whether GHGs directly and observably harmed public health and welfare at the local level was disputed. This changed with a 2007 Supreme Court case known as Massachusetts v. EPA, which began as an advocacy campaign by citizens concerned about climate change in 1999. Nineteen organizations petitioned the EPA to enact safeguards against rising GHG emissions. They feared that sea levels, spurred by global warming, would swell and submerge Massachusetts’s coastal lands if the EPA took no action to control climate change. The EPA refused, saying it did not have authority to regulate greenhouse gases but was instead tasked with addressing air pollution with direct physiological impact. The ensuing legal battle landed in the Supreme Court, which ruled in favor of Massachusetts, stating that the EPA did, in fact, have authority to regulate GHGs. The court further invited the EPA to produce a report on how GHGs could impact or endanger the environment and the public welfare, or provide a reasonable basis for not producing such a report.
Children’s explainer video about the greenhouse effect.
So in 2009, the EPA issued the Endangerment Finding. It added six greenhouse gases to the CAA’s list of harmful air pollutants, most notably Carbon Dioxide (CO2) and Methane. It also served as the foundation for modern emissions efficiency standards. Laws that followed the Endangerment Finding bolstered carbon reducing technologies in new motorized vehicles and power plants and offset millions of metric tons of GHGs. The Endangerment Finding has been the standard for environmental regulation around transportation and energy, two sectors with outsized impacts on the environment. According to EPA’s data (since removed from their website, but you can find it represented here), transportation accounts for 28 percent of climate pollution, and coal and gas power plants account for 25 percent. Up to the year 2025, the EPA had worked to strengthen efficiency and emissions-reduction rules for these sectors.
Backed by science
The Endangerment Finding has been widely supported in the scientific community for its responsiveness to the current climate reality. It is the product of thousands of scientific research studies contributed by the Intergovernmental Panel on Climate Change (IPCC), the U.S. Global Change Research Program (USGCRP), and the National Research Council (NRC).
What is striking about the rescission of 2026 is that the EPA does not appear to be holding science in high regard in its decision. The agency has instead based its evaluation of the finding on whether it holds up against legal technicalities. With that in mind, can the Endangerment Finding stand the test of scrutiny under a purely legal and statutory lens? And in terms of law, what new information has the Trump EPA brought to light that might undermine its credibility?
On the legal front: The argument for rescission of the Endangerment Finding
EPA asserts that several legal premises rule out the enforcement and even the existence of the Endangerment Finding. Two key claims in the agency’s arsenal are that.
- 1. The Clean Air Act was never intended as a safeguard against GHGs, so the EPA has no authority to regulate them.
- 2. EPA would first need explicit approval from Congress before it could regulate GHGS due to a concept known as the “Major Questions Doctrine.”
These are complicated arguments, and at first glance, they might seem outside of the ordinary person’s grasp to evaluate without helo from legal scholars. What is important to note, however, is that the laws that back the Endangerment Finding are not overly complicated or esoteric. For example, both the Clean Air Act and Massachusetts v. EPA made final decisions based on scientific findings about air pollutants. Straightforward. What makes things appear complicated is EPA Administrator Lee Zeldin’s rumination on dense legal theory. Referencing a cocktail of Supreme Court cases (that aren’t directly tied to the finding), Administrator Zeldin speculates that EPA does not in fact have the regulatory authority that the Supreme Court literally said it had. The agency claims that there lacks a sufficiently clear connection between greenhouse gases and public health and welfare to be able to control them as intended by the Clean Air Act.
“Emissions from new motor vehicles and new motor vehicle engines in the United States do not have a sufficiently close connection to the adverse impacts identified in the Endangerment Finding to fit within the legal meaning of ‘‘cause’’ or ‘‘contribute,” – it says on page 29 of the rescission document.
However, as the Endangerment Finding shows, greenhouse gas emissions heavily impact public health and welfare by raising global temperatures. “…heat is already the leading cause of weather-related deaths in the United States,” it says on page three of the report.
On page 30, the finding addresses how ozone pollution impacts air quality, even at the local level: “Climate change is expected to increase regional ozone pollution, with associated risks in respiratory illnesses and premature death.“
The problem with this particular legal rebuke is that legal decisions on this topic are necessarily based on scientific evidence. This is where the concept of a purely legal argument for rescission breaks down: when the Supreme Court ruled that the EPA must regulate greenhouse gases in 2007, it made clear that the EPA could only neglect to regulate GHGs if it could provide a “reasonable explanation” for not doing so. The ruling further provided that if the EPA were to “make[] a finding of endangerment, the [Clean Air Act] requires the agency to regulate.”
So the Supreme Court was clear that if GHGs were found to endanger public health, it would fall in the regulatory domain according to the Clean Air Act. This is why any legal argument either for or against regulation depends on scientific support. How could it be determined whether or not GHGs harm public welfare without concrete data and consensus? And again, the finding comprised thousands of scientific studies. Since the EPA has very weak foundations for reversing its own finding, it has doubled down on theoretical legal arguments.
“…regardless of facts, I have to follow the law.” EPA Administrator Lee Zeldin said on the subject of reversing the finding.
Legal arguments continued: The Major Questions Doctrine
Another, more theoretical legal line of argument the EPA uses involves the Major Questions Doctrine. The Major Questions Doctrine is not a law, but something that’s known as a “binding statutory interpretation” on which some Supreme Court Justices base their decisions in particular cases. It is rooted in the notion that if a government agency, for example, the EPA, seeks to make a decision of “vast economic and political significance,” it must first get clear authorization from Congress to execute that decision. Not all supreme court justices endorse the Major Questions Doctrine and many legal scholars are unclear about when a case becomes a “major question”, but the doctrine has been used in a handful of cases before. Administrator Zeldin argues that because the regulation of GHGs has vast economic impacts, having to do with the auto-industry, transportation, trade, etc., that it falls under the Major Questions Doctrine, and therefore, the EPA does not have regulatory powers over GHGs unless authorized by Congress. However, the Supreme Court never made a formal ruling stating that the regulation of GHGs falls under the Major Questions Doctrine. So to support his claim, Zeldin points to past cases where the doctrine was used to show a precedent for rescission.
Administrator Zeldin frequently points to a case called West Virginia v. EPA in 2022. In this case, West Virginia, along with other states and coal companies, sued the EPA because, at the time, the EPA was attempting to enforce “generation shifting” at non-renewable energy plant sites. Generation shifting, in this case, means transitioning from one energy source to another. The Biden Administration’s EPA was attempting to require coal plants to transform into less carbon-intensive gas-powered plants, and ultimately transition both coal and gas plants to wind, solar, and other renewable types of generation. The Biden Administration’s EPA lost the case, with the Supreme Court applying the Major Questions Doctrine to the ruling.
“Capping carbon dioxide emissions, at a level that will force a nationwide transition away from the use of coal to generate electricity, may be a sensible solution to the crisis of the day. But it is not plausible that Congress gave EPA the authority to adopt on its own such a regulatory scheme,” Chief Justice John Roberts determined.
At 00:48 Administrator Zeldin discusses his interpretation of the Major Questions Doctrine. NOTE: Administrator Zeldin uses the work “policies” instead of “questions” when discussing the doctrine.
So, Justice Roberts ruled that the EPA did not have the leeway to make generation shifting a regulatory requirement. However, while Administrator Zeldin touts this ruling as a clear precedent for revoking EPA’s regulatory responsibilities for GHGs, West Virginia v. EPA was a very different case from Massachusetts v. the EPA (the latter having cleared the way for the Endangerment Finding). Proponents of the Major Questions Doctrine will say that it is fundamentally rooted in the separation of powers (meaning no one agency or branch of government should have total decision-making control). The Supreme Court’s stated reason for siding with West Virginia and coal companies in 2022 was that requiring power plants to transition from fossil fuel generation to renewable energy generation is not the same as creating regulations on new technologies and processes that improve emissions efficiency (which is what the EPA had traditionally done). It wasn’t saying, however, that the EPA didn’t have regulatory authority over emissions. The Supreme Court was arguing that a mandatory transition away from fossil fuels fell outside the EPA’s regulatory abilities, and was instead in the domain of the legislative branch of government, a.k.a Congress.
The Supreme Court was not unanimous in its decision to rule against the Biden EPA, however, with dissenters arguing that, given the importance of abating climate change, congressional or Supreme Court interference on issues where the EPA has scientific authority on what’s best for public and environmental welfare is ill-advised. However, though the Supreme Court was divided on the ruling, it was not divided on whether or not greenhouse gases threaten public health and welfare, nor did it question that the EPA should regulate them. Despite the fact that the majority opinion writer, Justice Roberts, opposed EPA’s required transitions of power plants to renewable generation, If anything, his final ruling uses language that reaffirms EPA’s regulatory role.
“EPA had always set Section 111 emissions limits based on the application of measures that would reduce pollution by causing the regulated source to operate more cleanly,” Justice Roberts said (Section 111 of the Clean Air Act directly concerns GHGs).
Nevertheless, Administrator Zeldin uses this ruling to argue that the concept of regulating GHGs falls under the Major Questions Doctrine. But here, he runs up against reality. First, the Supreme Court never ruled that GHG regulation fell under the Major Questions Doctrine. Second, the Supreme Court already made clear what the EPA’s responsibilities were. The Massachusetts v. EPA case of 2007 (the case that ruled in favor of regulating GHGs) was about the EPA complying with its regulatory responsibilities to address air pollution. The Supreme Court ruled that the EPA was responsible for regulating GHGs under the Clean Air Act. So, Administrator Zeldin’s retroactive labelling of the Endangerment Finding as a Major Questions Doctrine issue, and neglecting the agency’s duties to comply with its own finding, if anything, appears to be moving counter to established law.
In its legal broadsides against the Endangerment Finding, EPA has faced legal challenges of its own
The EPA’s attempt at a legal takedown of the Endangerment Finding is shaky, but compared to its other lines of attack, its legal approach is arguably the most robust. The agency’s scientific challenges to the finding are meager, and for a debate so heavily centered on science, that stands out. So why does the repeal keep to the legal attacks?
In March of 2025, the EPA first announced it would reconsider GHG regulations. In the agency’s initial proposal, it offered two major bases for repeal. The legal basis and the scientific basis. On the legal front, it argued that Greenhouse gas emissions fell out of the intended regulatory scope of the Clean Air Act. On the scientific front, it argued that greenhouse gases could not be determined to be unsafe because the science around the issue contained “uncertainties”. Attempting to give scientific credibility to the repeal decision, the EPA enlisted the help of another federal agency. On the day EPA announced its reevaluation of the Endangerment Finding, the Department of Energy (DOE), headed by Trump appointee Chris Wright, released its own “scientific” take on greenhouse gases and climate science. Secretary Wright handpicked five known climate contrarians to produce a report titled: A Critical Review of Impacts of Greenhouse Gas Emissions on the U.S. Climate. It not only downplayed the potential impacts of heightened emissions, it even suggested that greenhouse gas-induced global warming may have a net positive effect on public health and welfare.
The DOE report was widely panned and discredited, so much so that the EPA did not rely on it to make its case to repeal the Endangerment Finding. Furthermore, the DOE working group that comprised the five contrarian scientists was disbanded in the fall of 2025, after a federal court ruled that it was operating illegally and unlawfully.
Pushback from the scientific community during the public comment period on the repeal included condemning letters from 22,000 members of the Union of Concerned Scientists. The commenters emphasized the overwhelming scientific consensus that GHGs harm both environmental and public welfare. So, in its final repeal, the EPA largely abandoned its scientific arguments and instead focused heavily on precarious legal ones. In a written response to the negative public reaction to the rescission, the EPA said this:
“Therefore, comments related to climate science are out of scope of this rulemaking.” – EPA.
Conclusion
The EPA’s legal approach to contesting the Endangerment Finding is arguably its most fleshed out, but that’s not saying much. There is generally more latitude for interpreting laws than there is for interpreting hard scientific data, and the agency took full advantage of this. Its positions on this front are still demonstrably weak and legally questionable. Even in a vacuum that excludes scientific consensus, the agency disregarded official rulings mandating that the EPA must regulate GHGs. Of course, this issue is not in a vacuum, and despite EPA’s efforts to sidestep the scientific discussion in its repeal, it could not avoid the topic completely. EPA officials continue to spout falsehoods to undermine confidence in the scientific consensus around climate change. What those disputes are and whether or not they are worthy of consideration is the topic of the next blog in this series, which covers the agency’s scientific rationale for reversing the finding.