The U.S. Department of Justice (DOJ) filed two federal court complaints last week against the California Air Resources Board (CARB), challenging the enforcement of emissions standards that DOJ contends are preempted under the Clean Air Act.
According to the DOJ, CARB is enforcing these standards through its Clean Truck Partnership, despite recent congressional actions invalidating EPA’s previously granted preemption waivers. In June 2025, President Trump signed joint congressional resolutions that nullified EPA waivers for CARB’s heavy-duty truck regulations. DOJ argues that, without those waivers, enforcement of these regulations violates federal law.
Acting Assistant Attorney General Adam Gustafson of the Environment and Natural Resources Division said the state’s actions are an attempt to bypass federal authority, stating that “agreement, contract, partnership, mandate — whatever California wants to call it, this unlawful action attempts to undermine federal law.”
The DOJ’s Environment and Natural Resources Division (ENRD) filed motions to intervene as plaintiffs in related cases pending in the Eastern District of California and the Northern District of Illinois. In parallel, the DOJ filed appellate motions in a separate proceeding concerning light-duty vehicle emissions rules, which it also alleges are preempted.
As stated in the press release, these actions advance “President Donald J. Trump’s commitment to end the electric vehicle (EV) mandate, level the regulatory playing field, and promote consumer choice in motor vehicles.”
