Dive Brief:
-
The Trump administration on March 12 filed a lawsuit versus California to block stricter emissions standards and what it described as a corresponding “illegal EV mandate.”
-
The action targets California’s Advanced Clean Cars I emission regulations, which were reinstated under an “Emergency Rule,” in September 2025. That was a reaction to Congress’ revocation earlier in the year of tighter standards adopted by the state in 2022, calling for 100% of new passenger vehicles to meet zero-emission standards by 2035.
-
The administration argues that ACC I standards are state-specific “backdoor fuel economy policies” that will drive up car prices and “force carmakers to radically revamp their production lines nationwide.”
Dive Insight:
With last week’s court filing, the Trump administration has waged an active challenge to California’s ACC I rules, which were rushed back into the forefront with emergency California Air Resources Board rulemaking that effectively still made EVs and PHEVs a mandated piece of the vehicle landscape.
CARB’s Emergency Rule “clarif[ies] the law to confirm that, at a minimum, CARB’s earlier-adopted standards, which have extant federal preemption waivers not subject to the recent congressional resolutions, are operative.”
The updated ACC II rules adopted by California in 2022 called for 22% of new passenger vehicles be zero-emissions in 2025. However, the requiements were invalidated by Congress in May 2025, with the passage of Republican-backed Congressional Review Act resolutions.
California’s ACC1 rules date back to 2009 and were last updated with a Clean Air Act waiver in 2013 calling for increasingly stringent CO2-based limits that went into effect from 2017 to 2025. The previous Trump Adminstration withdrew that waiver in September 2019, but the Biden administration restored the state’s authority in 2022.
The Justice Department argues that for the carbon-dioxide standards at the core of ACC, there is a direct relationship between gasoline consumed and CO2 emitted. Therefore, it violates federal law which prohibits individual states from adopting regulations related to fuel economy, making the ACC unenforceable.
The case was filed in the U.S. District Court for the Eastern District of California, the home district of CARB, which is headquartered in the capital city of Sacramento but performs its official duties throughout the state.
“Oppressive, expensive electric vehicle mandates drive up costs for American consumers and violate federal law,” said Attorney General Pamela Bondi, who also accused California of “using unlawful policies from the last administration to create exorbitant costs for our citizens.”
U.S. Transportation Secretary Sean Duffy criticized California Governor Gavin Newsom of “pushing Democrat’s radical EV fantasy.” A Justice Department press release emphasized that the allowance “would send car prices through the roof, restrict consumer choice, and undermine interstate commerce.”
Last year brought a flurry of additional actions, both in the form of executive orders and court filings. On June 12, 2025, the Trump administration announced three joint congressional resolutions that rescinded California’s most recent waiver authorizations. On the same day, 11 states filed a suit to invalidate the rescissions, while on June 20, 2025, the Supreme Court confirmed that energy industry plaintiffs can challenge the 2022 EPA waiver reinstatement, claiming economic injury.
All of that was before the administration revoked the EPA’s ability to regulate greenhouse gas emissions, with the nullification of a 2009 “endangerment” finding relating to direct harm to public health.
California has been granted a preemption waiver from the EPA in the past because its own emissions standards came before those created federally by the Clean Air Act. Under the waiver, other states may adopt and enforce tighter emissions standards if and only if they’re identical to the California ones.
Eleven other states (plus the District of Columbia) have adopted California’s ACC II regulation, amounting to roughly 25% of the U.S. light vehicle market. But 17 other states have adopted some aspects of California’s tighter standards without the rest of the framework. According to S&P Global Mobility, California and the states signing on to ACC II standards have accounted for about 45% of registered EVs.
