The U.S. government said on Friday it has filed lawsuits to block California from enforcing stricter emissions standards for heavy-duty trucks, arguing the rules conflict with federal law.
In complaints submitted to two federal courts this week, the Department of Justice (DOJ) said the California Air Resources Board (CARB) is preempted from implementing emissions rules that govern trucks and engines. Among them is the Clean Truck Partnership, a 2023 initiative aimed at reducing emissions while providing manufacturers with flexibility in meeting state requirements.
The DOJ said the move followed findings from a House of Representatives committee that CARB staff had prevented automakers from bringing vehicles to market unless they complied with the state’s contested standards. “This ongoing defiance of federal law must stop,” the department said. It added that California’s rules for light-duty vehicles are also preempted.
CARB declined to comment, while the office of California Governor Gavin Newsom did not immediately respond. Newsom, a Democrat, has promoted stricter emissions policies and electric vehicle adoption as part of efforts to address climate change.
California has historically exercised authority under the federal Clean Air Act to set tighter pollution limits than national standards, with more than 100 waivers granted since 1970. However, the DOJ argued that President Donald Trump’s June signing of congressional resolutions limits the state’s powers, including by voiding a waiver that allowed the Clean Truck Partnership.
“President Donald Trump and Congress have invalidated the Clean Air Act waivers that were the basis for California’s actions,” said Adam Gustafson, acting assistant attorney general for the DOJ’s environment and natural resources division. “CARB must respect the democratic process.”
The department said the lawsuits are intended to curtail California’s electric vehicle initiatives, standardize regulation across states, and promote consumer choice. Both filings seek to intervene in ongoing federal cases challenging the state’s emission rules, including the Clean Truck Partnership.
One case was lodged on Monday in Sacramento, California, by truck makers Daimler, International Motors, Paccar, and Volvo. Another was filed in December in Rockford, Illinois, by the American Free Enterprise Chamber of Commerce.