Four of the nation’s largest heavy-duty truck makers have filed a lawsuit in the U.S. District Court for the Eastern District of California, challenging the California Air Resources Board (CARB) and Governor Gavin Newsom’s ability to enforce certain state emissions regulations and the 2023 Clean Truck Partnership agreement.
Plaintiffs Daimler Truck North America, International Motors, PACCAR, and Volvo Group North America allege that California is attempting to require compliance with heavy-duty truck emissions standards that Congress recently preempted under the federal Clean Air Act. The complaint states that these manufacturers are now caught between conflicting directives — California requiring adherence to its rules, and the U.S. Department of Justice instructing them to stop following the same standards.
At the center of the dispute is the Clean Truck Partnership, an agreement announced in July 2023 between CARB, several truck manufacturers, and the Truck and Engine Manufacturers Association. The plaintiffs state that while the agreement was intended to align state and federal standards, it is now being applied to enforce regulations that no longer have federal waivers. The lawsuit also challenges provisions in the agreement that plaintiffs say limit manufacturers’ ability to contest CARB regulations.
According to the filing, Congress in June 2025 passed — and the president signed — resolutions under the Congressional Review Act that nullified EPA’s earlier waivers allowing California to implement three key programs: the Advanced Clean Trucks regulation, the Omnibus Low NOx regulation, and parts of Advanced Clean Cars II. The U.S. Department of Justice has since advised manufacturers that these programs, and the Clean Truck Partnership itself, are preempted by federal law.
California has filed its own lawsuit against the U.S. Environmental Protection Agency and the federal government, challenging the validity of those Congressional actions. That case is pending in federal court.
In their suit, the truck makers are asking the court for declaratory and injunctive relief to clarify their regulatory obligations and prevent enforcement of state standards they argue are invalid under federal law. The complaint also raises constitutional claims related to free speech and the ability to petition the government.
