The Environmental Protection Agency is proposing a rule to roll back a 2009 finding that allowed the EPA to address climate change under the Clean Air Act. If finalized, the new EPA proposed rule would roll back greenhouse gas emissions regulations for vehicles, including heavy-duty trucks.

On July 29, EPA Administrator Lee Zeldin announced the agency's proposed rule to rescind the 2009 Endangerment Finding that classified greenhouse gas emissions as harmful pollutants.

If it becomes a final rule, it would repeal all resulting greenhouse gas emissions regulations for motor vehicles. For trucking, that goes back to EPA’s greenhouse gas standards set in 2011 for medium-duty vehicles and heavy-duty vehicles and engines, and would affect GHG Phase 2 and GHG Phase 3 standards.

“With this proposal, the Trump EPA is proposing to end 16 years of uncertainty for automakers and American consumers,” said Zeldin.

The EPA move follows President Trump signing a resolution to revoke California’s waiver to set its own clean trucks rules.

What is the Endangerment Finding?

The Endangerment Finding is the legal prerequisite used by the EPA to regulate emissions from new motor vehicles and new motor vehicle engines. 

Without it, EPA would lack the authority under the Clean Air Act to create standards for greenhouse gas emissions. 

Congress tasked EPA under Section 202(a) of the Clean Air Act with prescribing emission standards for new motor vehicles and engines when the administrator determines that emissions of an air pollutant from any class of vehicles cause or contribute to air pollution that endangers public health or welfare.

The Endangerment Finding that determined half a dozen greenhouse gas pollutants did just that was published in 2009. It followed a U.S. Supreme Court decision in 2007 that ordered the EPA to make a scientific determination whether these pollutants endanger health or welfare.

In 2009, the EPA determined that carbon dioxide, methane, and four other climate pollutants do endanger public health. That allowed it to issue regulations aimed at mitigating climate change under the Clean Air Act.

But Zeldin, in announcing plans to rescind the Endangerment Finding, said the agency has heard from stakeholders that “EPA's GHG emissions standards themselves, not carbon dioxide which the Finding never assessed independently, was the real threat to Americans’ livelihoods.”

Zeldin said if finalized, rescinding the Endangerment Finding and resulting regulations “would end $1 trillion or more in hidden taxes on American businesses and families.”

Why Does EPA Want to Rescind the GHG Endangerment Finding?

In March, Zeldin announced that the EPA was kicking off a formal reconsideration of the 2009 Endangerment Finding in collaboration with the Office of Management and Budget and other relevant agencies.

At the same time, he announced the agency would reconsider the Model Year 2027 and Later Light-Duty and Medium-Duty Vehicles regulation and Greenhouse Gas Emissions Standards for Heavy-Duty Vehicles. 

In announcing the proposed rule July 29, the EPA said much has changed since the 2009 Endangerment Finding was issued, including new scientific and technological developments that warrant review. 

EPA’s new proposed rule cites updated scientific data that challenge the assumptions behind the 2009 Endangerment Finding. Cited data includes the updated studies and information in the Department of Energy’s 2025 Climate Work Group study that is concurrently being released for public comment.  

The agency also pointed to Supreme Court decisions since that time that clarified the scope of EPA’s authority under the Clean Air Act. The decisions emphasized that major policy determinations must be made by Congress, not by administrative agencies, according to an EPA news release.

Praise from Trucking Industry for EPA Deregulatory Action

The American Trucking Associations praised the EPA for taking action to “eliminate the unachievable Greenhouse Gas Phase 3 emissions standards that threatened to disrupt the supply chain and derail the trucking industry’s environmental progress.”

The Phase 3 GHG rules were characterized by many critics as essentially an electric-truck mandate. 

“It kicked innovation to the curb by discarding available technologies that can further drive down emissions at a fraction of the cost,” said ATA President & CEO Chris Spear. 

“The trucking industry supports cleaner, more efficient technologies, but we need policies rooted in real-world conditions.”

Modern trucks produce 99% fewer nitrogen oxide (NOx) and particulate matter emissions than those on the road decades ago, and new trucks cut carbon emissions by over 40% compared to trucks manufactured in 2010, ATA noted. As a result, 60 of today’s trucks emit what just one truck did in 1988.  

What’s Next for EPA's Proposal to Rescind the Endangerment Finding?

The repeal isn’t final yet. A proposed rulemaking sets for the proposal and asks for comments on the rule, which the agency is required by law to consider before publishing a final rule..

This lates deregulatory action by the Trump administration will no doubt face more legal challenges in court from groups such as the Environmental Defense Fund, which has repeatedly sued the Trump administration over changes that weaken environmental protections. 

Further information on the public comment process and instructions for participation will be published in the Federal Register and on the EPA website. 

Pushback from Environmental Groups

Environmental groups criticized Zeldin's announcement.

“The EPA’s rollback threatens to derail investment, penalize early adopters, and inject instability into a market that needs certainty to thrive,” said an email statement from Idle Giants, a coalition of groups that support the adoption of electric heavy-duty trucks.

EPA's GHG Phase 3 standards, which were designed to accelerate the adoption of zero-emission trucks starting in model year 2027, "are critical not only for curbing pollution but also for giving clarity and confidence to fleets investing in battery-electric truck technology," according to the email.

“Let’s be clear, this move doesn’t help the trucking industry. It hurts it,” said Craig Segall, former Deputy Executive Officer and Assistant Chief Counsel of the California Air Resources Board, in the statement.

“It penalizes fleets that have already committed to electric trucks and throws a wrench into long-term planning for businesses across the industry. It creates market instability just when we need certainty.” 

Guillermo Ortiz, Senior Clean Vehicles Advocate, National Resources Defense Council, put it this way in a statement: 

"Imagine investing in the future, only to have the rug pulled out from under you by your own government. That’s the harsh reality for the fleets and manufacturers who invested in clean trucks, now penalized for their leadership.”