The U.S. Environmental Protection Agency is urging a California federal court not to dismiss its intervenor claims alleging that the state violated the Clean Air Act through its adoption of new emissions standards for heavy duty trucks.

In the brief, filed Friday, the EPA said the court should find that the California Air Resources Board, or CARB, violated the Clean Air Act by adopting the so-called Advanced Clean Fleets Rule without seeking a waiver first, and that the waiver is not only necessary for enforcement.

According to the brief, the text of the Clean Air Act requires a waiver before a state can adopt emissions regulations beyond what the federal law provides, and California cannot get around that by begging forgiveness instead of asking for permission.

While the EPA may have allowed this practice to happen in the past, the EPA said what matters now is the proper interpretation of the statute, and the best interpretation of the law is that a waiver is necessary before the state adopts or attempts to enforce the regulations.

In the motion, the government said in a footnote that it is not opposing the state's bid to dismiss Gov. Gavin Newsom as a defendant.

The suit was initially filed by Daimler Truck North America LLC, International Motors LLC, Paccar Inc. and Volvo Group North America LLC in August, with the automakers challenging the so-called Clean Truck Partnership they brokered with California in July 2023 in light of the current administration's attacks on the state's regulations.

Under the Clean Truck Partnership, vehicle makers agreed to gradually adopt zero-emissions technology and eliminate the sale of heavy-duty diesel trucks in accordance with three CARB regulations: the Omnibus Low NOx regulations for heavy-duty engines and vehicles, the Advanced Clean Trucks rule and the Advanced Clean Fleets rule.

The government intervened shortly after the suit was filed, and earlier in October, the state moved to dismiss, arguing the federal government does not have standing to pursue its claims against the governor or to challenge future sales requirements.

In Friday's brief, the government argued that even if the waiver was not necessary for adoption of the regulations, the Clean Truck Partnership agreement is effectively enforcing those regulations, as the manufacturers would need to begin working now to meet the 2036 deadline the state has set for its emissions goals.

As to the government's standing, the EPA argued that the U.S.'s sovereign interests are harmed when its laws are violated and when any state usurps the federal government's regulatory authority, which the CTP and California's emissions regulations have done.

A spokesperson for the EPA declined to comment Monday.

Representatives for the other parties could not immediately be reached for comment Monday.

The California Air Resources Board is represented by Rob Bonta, Myung J. Park, Benjamin P. Lempert, David M. Meeker, Jonathan A. Wiener and Elaine Meckenstock of the California Attorney General's Office.

Daimler Truck North America is represented by Benjamin Wagner, Rachel S. Brass, Stacie B. Fletcher, Miguel A. Estrada and Veronica J.T. Goodson of Gibson Dunn & Crutcher LLP.

International Motors is represented by Robin M. Hulshizer, Arthur Foerster, Kevin M. Jakopchek and Belinda S. Lee of Latham & Watkins LLP.

Paccar is represented by Eugene Illovsky and Kevin Calia of Illovsky Gates & Calia LLP and Joseph A. Ostoyich, William Lavery, Steve Nickelsburg, Danielle Morello and Dorothea R. Allocca of Clifford Chance LLP.

Volvo Group North America is represented by Jeffrey M. Goldman, T. Scott Mills, Jeremy Heep and Daniel J. Boland of Troutman Pepper Locke LLP.

The EPA is represented by John K. Adams and David D. Mitchell of the U.S. Department of Justice's Environment and Natural Resources Division and Edward A. Olsen of the U.S. Attorney's Office for the Eastern District of California.

The federal government is represented by John K. Adams and David D. Mitchell of the DOJ's Environment and Natural Resources Division.

The case is Daimler Truck North America LLC et al. v. California Air Resources Board et al., case number 2:25-cv-02255, in the U.S. District Court for the Eastern District of California.