15 years of emission regulations on the chopping block

The Environmental Protection Agency plans to reverse its findings on greenhouse gases. This move will erase vehicle emission rules set over the past 15 years.

At an Indiana Kenworth dealership, EPA Administrator Lee Zeldin announced the agency will start the process to withdraw the 2009 “endangerment finding.” That single document has been the foundation of emission regulations since it took effect in 2010.

“We heard loud and clear the concern that EPA’s GHG emissions standards themselves, not carbon dioxide – which the finding never assessed independently – (were) the real threat to Americans’ livelihoods,” Zeldin said in a statement. “If finalized, rescinding the endangerment finding and resulting regulations would end $1 trillion or more in hidden taxes on American businesses and families.”

The endangerment finding allowed the EPA to create several vehicle emission rules. One example is the “Greenhouse Gas Emissions Standards for Heavy-Duty Vehicles – Phase 3.” Finalized last March, this rule set strict emission standards for heavy-duty trucks from model years 2027 to 2032. By 2032, 25% of sleeper cab tractors must be zero-direct-emission.

Trucking groups criticized the new rule, claiming the mandates are unworkable.

Todd Spencer, president of the Owner-Operator Independent Drivers Association, called the truck emission standards an “assault on small-business truck drivers.”

OOIDA and several organizations, along with Republican-led states, have filed legal challenges to the rule. These cases are on hold while the EPA decides its next steps under a new administration.

In February, Sen. Bernie Moreno, R-Ohio, introduced the Transportation Freedom Act. This act would repeal the Phase 3 greenhouse gas truck emission standards and other rules for passenger vehicles. Two weeks later, Sen. Markwayne Mullin, R-Okla., introduced the Preserving Choice in Vehicle Purchases Act. This bill would prevent the Clean Air Act from stopping the sale of vehicles with internal combustion engines. OOIDA supports both bills.

In March, Zeldin announced that the EPA would reconsider the Phase 3 truck emission rules and the 2022 heavy-duty nitrogen oxide rules. The trucking industry applauded the announcement.

“Small-business truckers make up 96% of trucking and could be regulated out of existence if the current standards were to be implemented,” Spencer said. “Mom-and-pop trucking businesses would be suffocated by the sheer cost and operational challenges of effectively mandating zero-emission trucks. Vehicle reliability and affordability are top priorities for OOIDA members, and we have yet to see proof that electric commercial motor vehicles are a practical option for most trucking businesses considering the price tag and lack of charging infrastructure. We commend EPA Administrator Zeldin on his realistic approach to emissions regulations. We will be working with EPA and Congress on a path forward that prioritizes listening to the men and women of the trucking industry.”

Supporters of vehicle emission rules argue otherwise.

Guillermo Ortiz, a senior clean vehicles advocate at the National Resources Defense Council, said the EPA’s recent move is “a gift to oil executives” and “a setback for American innovation.” Craig Segall, former deputy executive officer of the California Air Resources Board, said the proposed rule harms the trucking industry.

“Let’s be clear, this move doesn’t help the trucking industry,” Segall said. “It hurts it, 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.”

What is the endangerment finding?

Since 2010, strict vehicle emission rules have hinged on the EPA’s endangerment finding.

Back in 1999, more than a dozen environmental organizations petitioned the EPA to regulate greenhouse gas emission from vehicles under the Clean Air Act. That petition was denied in 2003 under George W. Bush. At the time, the EPA said it lacked authority to regulate greenhouse gas emission related to climate change.

Legal challenges followed, leading to a landmark Supreme Court decision. In 2007, the high court ruled that greenhouse gases are air pollutants under the Clean Air Act. Consequently, the EPA’s previous position was invalidated.

However, the EPA had to prove there was a legit reason to move forward. The Supreme Court required the agency to determine if greenhouse gases pose a danger to public health and welfare or if the science is too unclear to make that determination.

Later that year, the EPA sent its determination to the Office of Management and Budget. This would become the endangerment finding. After the regulatory process, it was finalized in December 2009 and took effect in January 2010.

That single document would be the legal foundation for subsequent emission regulations. Without the endangerment finding, regulating greenhouse gas emission from vehicles may not be possible.

Dozens of legal challenges to the endangerment finding poured in after it was finalized. All of those challenges were struck down by a federal court of appeals in 2012, which would survive petitions to the Supreme Court.

What’s next?

A comment period for the proposed rule will open, but legal challenges are likely.

Comments on the plan to rescind the 2009 endangerment finding will be accepted through Sept. 15. Those can be submitted by going to Regulations.gov and searching Docket ID No. EPA-HQ-OAR-2025-0194. The EPA has also set up a webpage about the proposed rule here.

Two public hearings will take place on Aug. 19 and 20. To pre-register, email EPA-MobileSource-Hearings@epa.gov. A third session might occur on Aug. 21 if needed.

Even if the rule is finalized, it will face strong opposition. In March, the Environmental Defense Fund filed a lawsuit against the EPA for not providing records related to Zeldin’s recommendation to withdraw the endangerment finding.

Former Washington Gov. Jay Inslee told States Newsroom that lawsuits from Democratic states are almost certain.

“If a lawsuit hasn’t been filed yet, I’ll have to call (Washington Attorney General) Nick Brown and tell him to hurry up,” Inslee said. “It’s been a couple hours now.” LL