Four of the largest commercial truck makers in North America Daimler Truck North America (DTNA), Navistar (International), Paccar Inc., and Volvo Group North America have filed a high-stakes federal lawsuit against the California Air Resources Board (CARB) and Governor Gavin Newsom, citing conflicting regulatory demands that threaten their operations nationwide.
At the heart of the lawsuit is the claim that California is enforcing emissions regulations that are no longer valid under federal law a move the truck makers say places them in legal and operational jeopardy.
The Clean Truck Partnership: Agreement Turned Legal Minefield
In July 2023, the four manufacturers along with other stakeholders like the Truck and Engine Manufacturers Association signed on to the Clean Truck Partnership, a California-led initiative. In exchange for regulatory flexibility and state incentives, OEMs agreed to follow CARB’s more stringent emissions regulations and gradually transition to zero-emission vehicles.
However, this partnership has become a legal flashpoint after the U.S. Department of Justice weighed in. In a cease-and-desist letter sent to DTNA, the DOJ’s Environment and Natural Resources Division declared that: “Because CARB’s regulations are pre-empted, the Clean Truck Partnership is pre-empted and unlawful. You must therefore immediately cease and desist your compliance with both the Clean Truck Partnership and its pre-empted state vehicle emission regulations.”
Manufacturers Say They’re Stuck Between Two Governments
The OEMs argue they’ve been “irreparably harmed” by the regulatory uncertainty. On one side, California mandates compliance with its environmental rules or threatens to bar manufacturers from selling in the state, exclude them from incentive programs, and impose civil penalties. On the other side, the federal government insists those very regulations are illegal under the Clean Air Act, which reserves emissions policy authority for the U.S. Environmental Protection Agency (EPA).
“Plaintiffs are caught in the crossfire,” the lawsuit says. “California demands that OEMs follow pre-empted laws; the United States maintains such laws are illegal and orders OEMs to disregard them. This situation is not tenable.”
The Federal Backdrop: Trump Reverses Biden-Era Waivers
In June 2024, former President Donald Trump rolled back a set of Biden-era EPA waivers that had allowed California to set its own transportation emissions rules, including mandates for electric trucks and stricter diesel engine standards. These waivers, long controversial, gave California unique authority under the Clean Air Act authority that Trump’s administration now argues is invalid.
Industry groups like the American Trucking Associations (ATA) cheered the reversal, viewing it as a move toward national consistency.
ATA President Chris Spear: “This is not the United States of California. With the stroke of his pen, President Trump is restoring the certainty that the trucking industry needs to deliver for our nation as we continue to reduce our environmental impact.”
ATA also emphasized the logistical concerns around California’s electrification push. While a diesel truck can refuel in 15 minutes and drive 1,200 miles, most electric trucks require 6–8 hours of charging and offer a maximum range of about 200 miles. The group warned that California’s rules would mean more trucks on the road, slower freight movement, and insufficient charging infrastructure.
California Fights Back — With Lawsuits and Legislation
Despite federal pressure, California is not backing down. In June, the state sued the White House over Trump’s use of the Congressional Review Act to roll back its EPA waivers and doubled down on its zero-emissions agenda.
An executive order from Governor Newsom that same day reaffirmed the state’s commitment to the Clean Truck Partnership, directing CARB to publish progress reports every six months and pledging to continue funding clean fleet and manufacturer incentives.
The order specifically prioritizes “state incentive programs for clean manufacturers and fleets”, even as federal agencies warn such programs may now violate federal law.
Congress Gets Involved
The federal-state clash has now reached Capitol Hill. On August 11, 2025, House Energy and Commerce Committee Chairman Brett Guthrie (R-Ky.) questioned CARB executive officer Steven Cliff over the state’s ongoing enforcement of regulations that the federal government has deemed illegal.
“The committee is concerned about reports that California and other states that follow its lead are enforcing pre-empted vehicle emission regulations in violation of the Clean Air Act.”
Guthrie has requested documents from CARB to determine the extent of their compliance with federal law.
What It Means for Trucking and the Road Ahead
This lawsuit could dramatically reshape the regulatory landscape for commercial trucking in the U.S.
- If the courts side with the truck makers, California may lose its ability to enforce separate emissions rules a massive shift, given its role as a trendsetter in environmental policy.
- If California prevails, OEMs could be forced to juggle dual regulatory regimes one for California and its allied states, and another for the rest of the country.
For fleets and drivers, this battle translates into potential cost hikes, supply disruptions, and a murky roadmap for compliance as manufacturers weigh legal risk against market access.
With major legal, political, and environmental forces in play, the future of emissions regulation and the path to cleaner, more efficient trucking hangs in the balance.
