California and its California Air Resources Board (CARB) are facing yet another legal challenge following last week's lawsuit filed by several major truck OEMs over the former's Clean Truck Partnership.
[Related: OEMs file lawsuit over 'backdoor' enforcement of banned CARB regs]
The Department of Justice announced last Friday it filed two complaints in federal court against CARB's enforcement of the emissions standards set for OEMs in the Clean Truck Partnership (CTP), which was signed in 2023.
The DOJ is making its case by claiming federal law overrides state regulations, at least when it comes to setting certain environmental policies. In this situation, the DOJ argues that the Clean Air Act "preempts state regulation of vehicle emissions unless the Environmental Protection Agency (EPA) grants California a preemption waiver," which it did under the previous Biden administration.
Last June, President Trump invalidated the EPA's preemption waivers for CARB's heavy-duty truck regulations, claiming it would be impossible for the state to enforce its own regulations.
Enter the controversial Clean Truck Partnership.
This was California’s so-called “backdoor” legal tactic of last resort—essentially a handshake agreement that CARB claims still binds OEMs to follow its emissions regulations, even though those regulations have been officially revoked.
Both the DOJ and major OEMs are now legally challenging the CTP's legitimacy. The DOJ's Environmental and Natural Resources Division (ENRD) filed motions to intervene specifically with two pending cases: in the Eastern District of California and Northern District of Illinois.
"Agreement, contract, partnership, mandate—whatever California wants to call it, this unlawful action attempts to undermine federal law," said Acting Assistant Attorney General Adam Gustafson of ENRD. "President Donald Trump and Congress have invalidated the Clean Air Act waivers that were the basis for California’s actions. CARB must respect the democratic process and stop enforcing unlawful standards."
Alongside its California lawsuit, the ENRD moved to dismiss two related cases in the Ninth Circuit, where industry groups had challenged the EPA’s preemption waivers for passenger vehicles. The DOJ says both cases are now moot after Congress nullified the waivers with joint resolutions.
