Revoking the Endangerment Finding: How Modern EPA Regulation of Greenhouse Gases Came and Went

Author: Paul Gould

September 3, 2026

[Image credit: Pexels]

The second Trump administration and its approach to scientific research have been defined by efforts to undermine trust in established national and international institutions of research and policy.  In seeking to upend international norms for how research is conducted, scrutinized, and verified, the administration is simultaneously reducing the number of opportunities for conducting research by universities, government agencies, and private institutions across numerous sectors by changing policy and withdrawing funding, and limiting the scope of the types of research that can be conducted, to accord with the desired outcomes preferred by the administration. Scientific research funded by the United States has led to numerous social benefits across a vast array of disciplines, and is often relied upon to inform international, federal, and state governing policies. When the reliability of the findings resulting from these projects cannot be counted upon to be sufficiently rigorous and dependable, solutions to issues that touch all levels of society are delayed, and people suffer.

On February 18, 2026, the Environmental Protection Agency published its rescission of the “endangerment finding,” the bedrock of federal climate policy. The endangerment finding was the conclusion from a 2009 analysis conducted by EPA, which established that greenhouse gas (GHG) emissions are air pollutants, as defined under the Clean Air Act, that contribute to pollution and endanger public health and welfare. The endangerment finding was the primary rationale providing EPA the necessary regulatory authority to impose limitations on greenhouse gas emissions from most types of gas-powered vehicles. At the time of the finding, the emissions from these vehicles constituted 23 percent of U.S. greenhouse gas emissions. The legal basis that led to the endangerment finding emerged as a result of a Supreme Court case, Massachusetts v. EPA, which held that the Clean Air Act requires EPA to regulate greenhouse gas emissions if EPA determines that, as a pollutant, greenhouse gases endanger public health and welfare, and that EPA must take steps to determine whether greenhouse gases do indeed endanger public health and welfare. Two years later, EPA completed their analysis and established the endangerment finding. Following this, the connection between vehicle emissions and greenhouse gas endangerment was confirmed by EPA, and new emissions regulations were implemented in conjunction with the National Highway Traffic Safety Administration beginning in 2010. According to JD Supra, a legal news website, “the final rule eliminates all federal greenhouse gas emission standards for motor vehicles and engines of model years 2012 to 2027 and beyond, along with associated compliance programs, credit provisions, and reporting obligations. The repeal immediately removes federal requirements to measure, report, certify, and comply with greenhouse gas emission standards for motor vehicles.” By attempting to rescind the endangerment finding and loosen emissions regulations, the Trump government is, without a proper scientific basis, deliberately ignoring the research findings of a previous administration, to the detriment of the American people and in defiance of the law.

The original action that led to the endangerment finding was a petition filed by the International Center for Technological Assessment on behalf of nineteen different environmental, political, and religious organizations. The right to petition is a mechanism provided for by the Administrative Procedure Act and the Clean Air Act, which allows anyone to petition a federal agency to issue, amend, or appeal an administrative rule. The petition requested the EPA to regulate four specific greenhouse gases in newly manufactured cars, and provided arguments for why the EPA has the authority and responsibility to regulate their emissions. This was based on their position that these greenhouse gases qualified as “air pollutants” under the Clean Air Act, meaning that any “air pollution agent…including any physical, chemical, biological, radioactive…substance or matter which is emitted into or otherwise enters ambient air.”

Furthermore, they argued that, as pollutants, they can reasonably be anticipated to endanger public health and welfare, and that regulating them can lead to a reduction in emissions. In 2001, the EPA published a notice seeking comment on the petition from the public, and in 2003, published another denying the petition for rulemaking. In October 2003, the ICTA, thirteen other environmental organizations, twelve states, three cities, and one territory filed a petition for review of EPA’s decision with the U.S. Court of Appeals for the D.C. Circuit. In July 2005, the court denied the petition, by a vote of 2 to 1, but each judge arrived at their decision using different reasoning. ICTA and the other petitioning groups, in response, filed an appeal with the U.S. Supreme Court. Separately from efforts by the petitioners, California submitted a request to EPA that the agency allow states to adopt individual emissions standards for motor vehicles, which would require a specific waiver, which EPA refused to grant, citing the impending SCOTUS decision.

In April 2007, the Supreme Court released its 5-4 decision finding that the petitioners had standing and that EPA had authority to regulate greenhouse gas emissions. The question of standing was central to one of the primary arguments advanced by EPA, which the court addressed in finding that despite greenhouse gases inflict widespread harm, and ostensibly no individual harm can be outlined by the petitioners, which would normally prevent a court from adjudicating on the matter, that if certain conditions are met that a party does have standing and a court can compel an action by the defendants. Specifically, if a party has “such a personal stake in the outcome of the controversy” and has shown “that the action injures him in a concrete and personal way,” then the actions requested by the petitioner need not resolve all harm suffered by transgression, but merely show “some possibility the requested relief will prompt the injury-causing party to reconsider the decision that allegedly harmed the litigant.” These assertions by the court were fundamental to their reasoning to find standing, and side with the petitioners.

The court also examined EPA’s decision to not classify greenhouse gas emissions as “air pollutants,” holding that the definition provided in the Clean Air Act was so sweeping that greenhouse gases assuredly fell within its purview. EPA’s argument that it did not believe Congress intended for EPA to regulate substances that contribute to climate change was held to be irrelevant, given that EPA could not provide any evidence that, following passage of the Clean Air Act, that Congress did not intend EPA to regulate greenhouse gases. According to Justice John Paul Stevens, author of the majority opinion, Congress intended when drafting the Clean Air Act that the broad language utilized should allow for changing science to influence later regulations. Since greenhouse gases “fit well within” the definition of air pollutants, it can be thus inferred that EPA has the statutory authority to regulate them.

In addition, the court addressed the contention that EPA’s regulation of greenhouse gas emissions as pollutants would infringe on the authority of the U.S. Department of Transportation to set fuel efficiency standards. The majority opinion held that although DOT has the responsibility for determining fuel efficiency standards, that does not absolve EPA of the responsibility, nor the ability, to regulate greenhouse gas emissions. One significant finding was that EPA had acted “arbitrarily and capriciously” in rejecting the original petition by ICTA and its co-petitioners. The statutory obligation is clear, stating that “[EPA] shall by regulation prescribe…standards applicable to the emission of any air pollutant from any class of new motor vehicles.” If scientific uncertainty on global warming was so profound, EPA would have to determine so in order to avoid its obligation to address and limit the role of greenhouse gases. The court found that the reasons provided by EPA for not performing the evaluation were based on policy considerations and not statute, and thus required EPA to make a decision about the impact of greenhouse gases, rather than simply deferring. It was this portion of the decision that required EPA to make a determination about the danger of climate change that would eventually lead to the endangerment finding.

Following the Supreme Court decision, EPA denied the request in the California petition, arguing that the section under which California had submitted the waiver was intended to allow states to address local and regional pollution problems, not global issues. It took a presidential election and change in administration before EPA began any endangerment analysis. In February 2009, under new administrator Lisa Jackson, EPA published a notice to reconsider the agency’s previous denial of California’s waiver, which it later withdrew.  On April 24th, EPA proposed a finding that “GHG emissions endangered public health and welfare and that GHG emissions from new motor vehicles and new motor vehicle engines were contributing to air pollution that endangers public health and welfare…” A revised and final version of the endangerment finding was published on December 15, 2009.

So what were the practical impacts of issuing the endangerment finding for manufacturers? In October 2009, EPA issued the “Mandatory Reporting of Greenhouse Gases Final Rule ” that created the Greenhouse Gas Reporting Program, which requires corporations from all sectors of the economy to report greenhouse gas emissions to EPA if above an agency-specified threshold level. In May 2010, EPA issued its “Tailoring Rule,” which limited the scope of entities required to obtain an operating permit required by the Clean Air Act, providing permitting obligation relief to small businesses and organizations. On December 17, 2010, EPA issued its “Mandatory Reporting of Greenhouse Gases” rule, which both imposed new reporting requirements and clarified existing obligations in the form of a Greenhouse Gas Reporting Program (GHGRP). Mandated by Congress in the FY2008 Consolidated Appropriations Act spending bill, it required reporting of greenhouse gas data from large emission sources and suppliers across a range of industry sectors. This new mandatory monitoring obligation rule specifically targeted sources that “in general emit 25,000 metric tons or more of carbon dioxide (CO₂) equivalent per year in the United States.” This targeted suppliers of fossil fuels that might not be directly emitted by the supplying facility, but whose products were eventually combusted and released the greenhouse gases. These direct emitting facilities had separate reporting requirements. An estimated “85-90 percent of the total U.S. GHG emissions from over 8,000 facilities are covered by the GHGRP.” Further expansions of the rule added new monitoring requirements for leaks from oil and gas equipment, established thresholds for which types of internal combustion engines were required to have their emissions data reported, and clarifications on thresholds for reporting by particular groups and emitting entities, as well as industry-wide emission limits for new power plants and oil refineries, and existing facilities which met certain criteria.

The scope of this piece does not allow for an examination of the net benefits of the implementation of these regulations, if not only because calculating them would require vast resource allocation, which to the author’s knowledge has not been taken. But to put into perspective why EPA determined greenhouse gas emission regulation was necessary, one need only consult the overwhelming majority of scientific literature. The question of the cause of observed and predicted global warming is still a politically divisive consideration in the United States. A Gallup poll conducted in 2021 shows little shift from the previous decade in worry about the present and future impacts of climate change, but notes a growing divide between conservative and liberal viewpoints. Republicans are much less likely to think that climate change poses an immediate danger, with most thinking it is either a far-off or nonexistent phenomenon.

These perspectives are at odds with almost the entirety of the scientific literature, and indeed a growing consensus of the cumulative causes of recent extreme weather patterns. The human rights implications of climate change are myriad and serious. At the national level, over half of the contiguous United States, and one-third of the population, saw their warmest March days on record this year. The effects of warmer winters range from higher levels of precipitation and winter storm activity in the North to drier winters with less snowmelt runoff and severe drought conditions in the Southwest. Another impact of global warming is the greater frequency and intensity of extreme weather events. Quicker than average Arctic warming has been found to contribute to more extreme cold patches, including the February 2021 Texas cold wave, and has only been increasing. Readers based in the United States will almost certainly be aware of the 2026 North American heatwave that began in late June. Starting June 28, 180 million people, nearly half of the United States, were under a “major” or “extreme” heat risk, according to the National Weather Service. Trains had to reduce speeds or fully cancel services, severe thunderstorms in New Jersey caused 250,000 power outages, and many Independence Day celebrations were canceled. Due to the heat wave from July 1-4, at least 44 heat-related fatalities were reported. From July 4-6, several rounds of severe thunderstorms caused over 1.3 million power outages and four fatalities.

Furthermore, climate models predict a 10-25% decrease in corn yields due to heat stress in the Midwest, with global market implications. The Western and Southwestern U.S. states, already dealing with chronic water shortages, could see significant reductions in agricultural output across all sectors, particularly in California. The Southeast may see pervasive heat and humidity stress crops like cotton, peanuts, and tobacco, as well as a spread of new pests and diseases that thrive in warmer, wetter conditions in the non-summer months. More intense precipitation events and greater pest pressure might also impact the Northeast. Crop yield reductions have direct implications for food security in the United States and the world. Reduced supply due to lower yields and supply chain disruptions will lead to higher prices, not only domestically but internationally as well. And the economic repercussions stretch to increased input costs, reduced farm income, land value depreciation, labor challenges exacerbated by dangerous fieldwork and the deportation policies of the Trump administration disproportionately affecting migrant laborers, and ripple effects across rural communities where agriculture is the dominant economic sector.

These are only some of the dangers resulting from climate impacts. The impacts on human rights issues, from environmental rights to labor rights, from concerns about the right to life and to equitable access to clean air and drinking water, are undeniably increasing and worsening. Global warming presents an existential threat to foundational protection of the right to be secure in one’s home and one’s body. By moving to rescind the endangerment finding, EPA is attempting to subvert the law, and thereby its statutory obligation to safeguard United States citizens from the harms of greenhouse gas emissions and climate change. At least one lawsuit has been filed to stop the rescission, with the legal implications due to be sorted out in coming years. A Supreme Court ruling on the repeal is entirely possible. But by moving to deregulate industries previously subject to EPA oversight, the administration is choosing to sacrifice the well-being and safety of the very people it has been tasked to protect.

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Glossary

• Accord - to be consistent or in harmony.

• Administrative Procedure Act - a federal act that governs the procedures of administrative law.

• Allegedly - asserted to be true or to exist.

• Allocation - apportionment for specific purposes or to particular persons or organizations.

• Amend - to change or modify (something) for the better.

• Analysis - a detailed examination of anything complex in order to understand its nature or to determine its essential features.

• Anticipate - to foresee and deal with in advance.

• Appeal - a legal proceeding by which a case is brought before a higher court for review of the decision of a lower court.

• Arbitrarily - in an arbitrary manner : at will.

• Array - to arrange or display in or as if in an array.

• Assertions - a declaration that something is the case.

• Assuredly - without a doubt.

• Authority - power to influence or command thought, opinion, or behavior.

• Basis - the principal component of something.

• Capriciously - not supported by the weight of evidence or established rules of law.

• Certify - to attest as being true or as represented or as meeting a standard.

• Clarifications - the act or process of clarifying.

• Classify - to consider (someone or something) as belonging to a particular group.

• Clean Air Act - the United States' primary federal air quality law, intended to reduce and control air pollution nationwide. Initially enacted in 1963 and amended many times since, it is one of the United States' first and most influential modern environmental laws.

• Combusted - burn.

• Compelled - to cause to do or occur by overwhelming pressure.

• Compliance - conformity in fulfilling official requirements.

• Conceptualizing - to interpret conceptually.

• Concrete - characterized by or belonging to immediate experience of actual things or events.

• Constituted - make up, form, compose.

• Consult - to ask the advice or opinion of.

• Contiguous - being in actual contact : touching along a boundary or at a point.

• Controversy - a discussion marked especially by the expression of opposing views.

• Criteria - a standard on which a judgment or decision may be based.

• Cumulative - increasing by successive additions.

• D.C. Circuit Court - is one of the thirteen United States Courts of Appeals. It has the smallest geographical jurisdiction of any of the U.S. courts of appeals, and it covers only the U.S. District Court for the District of Columbia.

• Deferring - put off, delay.

• Defiance - the act or an instance of defying, challenge.

• Detriment - injury, damage.

• Deny - to declare (something) to be untrue.

• Depreciation - the act of making a person or thing seem less valuable.

• Deportation - an act or instance of deporting.

• Disciplines - control gained by enforcing obedience or order.

• Disproportionately - being out of proportion.

• Disruptions - a break or interruption in the normal course or continuation of some activity, process, etc.

• Divisive - creating disunity or dissension.

• Dominant - commanding, controlling, or prevailing over all others.

• Eliminates - to put an end to or get rid of.

• Environmental Protection Agency - is an independent agency of the United States government tasked with environmental protection matters. 

• Evaluation - determination of the value, nature, character, or quality of something or someone.

• Exacerbated - to make (something bad or unpleasant) worse.

• Existential - grounded in existence or the experience of existence.

• Explicit -  fully revealed or expressed without vagueness, implication, or ambiguity : leaving no question as to meaning or intent.

• Fatalities - the quality or state of causing death or destruction.

• February 2021 Texas cold wave - the state of Texas suffered a major power crisis, which came about during three severe winter storms sweeping across the United States on February 10–11,13–17 (known as Winter Storm Uri), and 15–20. The storms triggered the worst energy infrastructure failure in Texas state history, leading to shortages of water, food, and heat.

• Fossil fuel - a fuel (such as coal, oil, or natural gas) formed in the earth from plant or animal remains.

• Frequency - the fact or condition of occurring frequently.

• Fundamental - serving as a basis supporting existence or determining essential structure or function : basic.

• Greenhouse gas - any of various gaseous compounds (such as carbon dioxide or methane) that absorb infrared radiation, trap heat in the atmosphere, and contribute to the greenhouse effect.

• Greenhouse Gas Reporting Program - requires reporting of greenhouse gas (GHG) data and other relevant information from large GHG emission sources, fuel and industrial gas suppliers, and CO₂ injection sites in the United States. Approximately 8,000 facilities are required to report their emissions annually, and the reported data are made available to the public in October of each year.

• Implementation - an act or instance of implementing something : the process of making something active or effective.

• Implications - a possible significance or future effect.

• Intend - to have in mind as a purpose or goal.

• Intensity - the quality or state of being intense especially : extreme degree of strength, force, energy, or feeling.

• International Center for Technical Assessment - a U.S. non-profit bi-partisan organization, based in Washington, D.C.. ICTA aims to provide the public with full assessments and analyses of technological impacts on society.

• Irrelevant - not relevant : inapplicable. 

• Justification - the act or an instance of justifying something : vindication.

• Litigant - one engaged in a lawsuit.

• Majority - a number or percentage equaling more than half of a total.

• Majority opinion - a judicial opinion agreed to by more than half of the members of a court. A majority opinion sets forth the decision of the court and an explanation of the rationale behind the court's decision.

• Mandated - officially required.

• Mandatory - required by a law or rule.

• Massachusetts v. EPA - a 5–4 U.S. Supreme Court case in which Massachusetts, along with eleven other states and several cities of the United States brought suit against the Environmental Protection Agency (EPA) to force the federal agency to regulate the emissions of carbon dioxide and other greenhouse gases (GHGs) that pollute the environment and contribute to climate change.

• Mechanism - a process, technique, or system for achieving a result.

• Migrant - a person who moves regularly in order to find work.

• Myriad - a very large number.

• National Highway Traffic Safety Administration - an agency of the U.S. federal government, part of the Department of Transportation, focused on automobile safety regulations.

• National Weather Service - an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the purposes of protection, safety, and general information.

• Nonexistent - not in actual or present occurrence.

• Notice - warning or intimation of something.

• Obligations - something (such as a formal contract, a promise, or the demands of conscience or custom) that obligates one to a course of action.

• Observed - to conform one's action or practice to (something, such as a law, rite, or condition) : comply with.

• Ostensibly - to all outward appearances.

• Outsized - an unusual size especially : a size larger than the standard.

• Oversight - regulatory supervision.

• Overwhelming - tending or serving to overwhelm.

• Perspective - a mental view or prospect.

• Petition - a formal written request made to an authority or organized body (such as a court).

• Petitioner - one who makes, submits, or signs a petition.

• Pollutants - something that pollutes especially : something (such as waste created by human activity) that makes an environment unsuitable or unsafe for use.

• Portion - an individual’s part or share of something.

• Predicted - to declare or indicate in advance especially : foretell on the basis of observation, experience, or scientific reason. 

• Procedural - of or relating to procedure especially : of or relating to the procedure used by courts or other bodies administering substantive law.

• Profound - having intellectual depth and insight.

• Provide - to supply or make available (something wanted or needed).

• Provisions - the act or process of providing.

• Purview - the range or limit of authority, competence, responsibility, concern, or intention.

• Radioactive - of, caused by, or exhibiting radioactivity.

• Rationale - an explanation of controlling principles of opinion, belief, practice, or phenomena.

• Regulatory - to govern or direct according to rule.

• Rejecting - to refuse to accept, consider, submit to, take for some purpose, or use.

• Reliability - the quality or state of being reliable.

• Repeal - to rescind or annul by authoritative act.

• Repercussions - an action or effect given or exerted in return : a reciprocal action or effect.

• Rescission - an act of rescinding.

• Revised - to look over again or make changes to in order to correct or improve.

• Rigorous - manifesting, exercising, or favoring rigor.

• Ripple - to flow in small waves.

• Scrutinized - to examine closely and minutely.

• Simultaneously - in a simultaneous manner : at the same time.

• Standing - the status of being qualified to assert or enforce rights in a judicial forum (such as a court) arising from a sufficient and protectable interest in the outcome of a legal case due to suffering or being threatened with actual injury as a result of the actions of the other party.

• Statutory - of or relating to statutes.

• Subvert - to overturn or overthrow from the foundation : ruin.

• Sufficiently - in a sufficient manner or to a sufficient degree.

• Supreme Court - the highest court in the federal judiciary of the United States. It has ultimate appellate jurisdiction over all U.S. federal court cases, and over state court cases that turn on questions of U.S. constitutional or federal law. It also has original jurisdiction over a narrow range of cases, specifically "all Cases affecting Ambassadors, other public Ministers and Consuls, and those in which a State shall be Party".

• Sweeping -  the act or action of one that sweeps.

• Theoretical - existing only in theory : hypothetical.

• Threshold - a level, point, or value above which something is true or will take place and below which it is not or will not.

• Transgression - infringement or violation of a law, command, or duty.

• Uncertainty - the quality or state of being uncertain : doubt.

• U.S. Court of Appeals - the intermediate appellate courts of the U.S. federal judiciary. They hear appeals in cases from the U.S. district courts and from certain federal administrative agencies. Their decisions may be reviewed by the Supreme Court of the United States.

• Verified - to establish the truth, accuracy, or reality of.

• Waiver - the act of intentionally relinquishing or abandoning a known right, claim, or privilege.