The Trump administration is set to rescind the Environmental Protection Agency’s 2009 endangerment finding, a move that would halt federal regulation of greenhouse gases under the EPA Clean Air Act and is expected to prompt significant legal challenges.
White House press secretary Karoline Leavitt said Tuesday that the action would represent “the largest deregulatory action in American history.” EPA Administrator Lee Zeldin is expected to join President Trump at the White House on Thursday to formalize the decision.
The 2009 endangerment finding determined that greenhouse gases, including carbon dioxide and methane from fossil fuel development and combustion, pose a threat to public health and welfare. That determination has served as the legal foundation for a wide range of federal climate regulations.
Legal Foundation and Historical Context
In 2007, the U.S. Supreme Court ruled in Massachusetts v. EPA that the agency must regulate carbon dioxide and other greenhouse gases under the Clean Air Act. Two years later, during the Obama administration, the EPA issued the endangerment finding, concluding that greenhouse gases in the atmosphere endanger public health and welfare.
The finding underpins federal rules governing emissions from coal- and gas-fired power plants, vehicle exhaust, and methane emissions from the oil and gas sector.
On the first day of his second term, President Trump signed an executive order directing the EPA administrator to submit recommendations on the legality and continuing applicability of the endangerment finding. The directive echoed recommendations included in the Heritage Foundation’s Project 2025 plan, which calls for limiting climate-related regulation.
Zeldin first announced the EPA’s intention to eliminate the endangerment finding last March. In a news release at the time, he said the agency aimed to reduce costs for American families, expand domestic energy production, and support the auto industry.
The EPA now argues that the Clean Air Act does not provide legal authority to regulate greenhouse gases. The administration has contended that the original finding was established in a “flawed and unorthodox” manner and did not strictly adhere to the Clean Air Act’s statutory language.
Environmental groups dispute that interpretation. Abigail Dillen, president of Earthjustice, said the law requires the EPA administrator to regulate air pollution “which may reasonably be anticipated to endanger public health or welfare” and indicated that litigation would follow.
Implications for Vehicle Emissions Standards
Because the endangerment finding stemmed from a Clean Air Act provision focused on vehicle emissions, its rescission is expected to end federal limits on greenhouse gas emissions from cars and trucks. Transportation remains the largest direct source of greenhouse gas emissions in the United States.
Under the Biden administration, vehicle standards were tightened significantly. The White House projected that automakers would need to have electric vehicles account for up to 56% of sales by 2032 to comply with the standards.
The Trump administration is poised to eliminate those restrictions. It has also blocked California’s authority to set its own vehicle emissions rules, reduced the stringency of federal fuel economy standards, and, with congressional support, eliminated penalties for noncompliance with those standards. In addition, Congress ended the federal consumer tax credit for electric vehicles, and the administration delayed or redirected funding intended to support electric vehicle charging infrastructure.
Electric vehicles accounted for about 10% of new car sales in 2024. Although traditional automakers argued that prior standards did not align with market conditions, industry groups have expressed differing views on regulatory stability. MEMA, which represents auto parts manufacturers, asked the EPA to maintain greenhouse gas rules to provide long-term certainty for U.S. companies competing in the global electric vehicle market.
Some industry participants have also warned that eliminating the endangerment finding entirely, rather than replacing it with revised standards, could create regulatory uncertainty and lead to state-by-state emissions rules in the absence of a federal framework.
On Tuesday, Leavitt said rescinding the finding would save $1.3 trillion, largely through lower vehicle sticker prices. While electric vehicles typically carry higher upfront costs in the United States, economic analyses have found that drivers may realize savings over time through reduced fuel costs.
Scientific and Administrative Considerations
Historically, EPA regulations have relied heavily on scientific findings. In seeking to overturn the endangerment finding, the current EPA has emphasized legal arguments. The science cited in the agency’s proposed rule came from the Department of Energy’s Climate Working Group. Independent scientists issued a joint rebuttal of the group’s report, calling it rife with errors. The panel has since been disbanded, and a federal judge ruled that the Energy Department violated public records laws in creating it.
The administration’s action follows three consecutive years identified as the hottest on record and a series of extreme weather events across the United States, including flooding and wildfires.
The United States is the largest historical emitter of man-made greenhouse gases and previously committed to international emissions reduction efforts under the 2015 Paris climate agreement. President Trump has withdrawn the United States from that agreement and from the 1992 treaty that underpins it.
Once the EPA publishes its final decision in the Federal Register, legal challenges are expected. Observers anticipate that the matter could ultimately return to the U.S. Supreme Court for review.
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