California Agrees to Repeal Advanced Clean Fleets Mandate in Legal Settlement

In a significant legal victory for opponents of California's ambitious environmental policies, the state has agreed to formally repeal much of its controversial Advanced Clean Fleets (ACF) electric-truck mandate. This move comes as part of a legal settlement after a coalition of 17 states, led by Nebraska, challenged the ACF rules in court.

The legal settlement, announced by Nebraska Attorney General Mike Hilgers, comes after the state of California was unable to secure the necessary waiver from the U.S. Environmental Protection Agency (EPA) to enforce key provisions of the ACF. As a result, the state will no longer enforce the ACF rule and has committed to initiating the process to repeal it.

Why California’s Advanced Clean Fleets Mandate Was Controversial

The Advanced Clean Fleets rule was the second phase of California’s broader initiative to transition to zero-emission vehicles in the state’s trucking sector. Unlike the earlier Advanced Clean Trucks rule, which focused on truck manufacturers and required them to sell a certain percentage of zero-emission trucks, the ACF specifically targeted fleet operators.

The rule would have mandated that fleets operating in California purchase an increasing number of zero-emissions trucks on a phased schedule. This mandate applied regardless of where the fleet was headquartered, meaning even out-of-state companies would have been affected. Given California’s size and influence on national logistics—especially with its access to major international ports—this rule was expected to have far-reaching impacts on the entire U.S. supply chain.

Additionally, the ACF would have phased out the sale of new internal-combustion trucks by 2036 and required large trucking companies to convert their medium- and heavy-duty fleets to zero-emission vehicles (such as battery-electric or hydrogen fuel cell trucks) by 2042. Critics, particularly within the trucking industry, argued that the ACF set unrealistic goals for electric-truck adoption, overlooking alternative emissions-reduction methods and placing significant financial burdens on fleets that were already facing challenges.

The Legal Challenge and Settlement

The lawsuit challenging the ACF was spearheaded by Nebraska, joined by 16 other states—Alabama, Arkansas, Georgia, Idaho, Indiana, Iowa, Kansas, Louisiana, Missouri, Montana, Oklahoma, South Carolina, Utah, West Virginia, and Wyoming. Also participating in the lawsuit were the Nebraska Trucking Association and the Arizona State Legislature.

The states contended that California’s ACF mandate would have had a profound impact on the national economy, disrupting supply chains and creating additional costs for businesses across the country. The legal challenge specifically focused on the lack of a necessary waiver from the EPA, which California needed to enforce the mandate.

In response to this challenge, California regulators have conceded that they cannot enforce the ACF’s most contentious provisions without an EPA waiver under the Clean Air Act. Given the current political climate, the likelihood of securing this waiver is seen as increasingly remote, leading California to abandon its efforts to enforce the ACF.

What Happens Next?

The settlement outlines several key next steps for the California Air Resources Board (CARB) in relation to the ACF:

1. Reevaluation and Repeal: CARB staff will present a proposal to repeal the High-Priority Fleet and Drayage Fleet requirements of the ACF regulation. This proposal will be discussed in a public hearing by October 31, 2025. If the Board approves the repeal, CARB will submit the rulemaking to California’s Office of Administrative Law (OAL) for approval no later than August 31, 2026.

2. Enforcement Halt: CARB has agreed not to enforce the ACF’s High-Priority Fleet and Drayage Fleet requirements during the interim period, which began on November 1, 2023, and will continue until CARB or the OAL takes final action on the repeal.

3. 2036 Ban on Internal-Combustion Trucks: CARB also conceded that it will not enforce the provision requiring 100% zero-emission vehicle sales for medium- and heavy-duty trucks starting in 2036 unless it obtains an EPA waiver under the Clean Air Act. Given the uncertainty around obtaining such a waiver, it remains unclear if or when this provision will be enforced.

The Bigger Picture: CARB and the EPA Waiver

The failure to secure the EPA waiver for ACF is a major blow to California’s regulatory approach to trucking emissions. In fact, California’s Advanced Clean Fleets mandate had been effectively stalled since January 2021, when the California Air Resources Board withdrew its request for an EPA waiver under the previous administration. The decision came amid the realization that the incoming Biden administration would be unlikely to grant the waiver, given its more lenient stance on emissions regulations.

The Trump administration, along with a Republican-led Congress, had already made moves to block California’s environmental regulations, including the Advanced Clean Trucks rule, which had received an EPA waiver under Biden. The states involved in the lawsuit against California took credit for contributing to the failure of the waiver request, ultimately forcing California to backtrack on the ACF.

What’s Next for the Trucking Industry?

For fleets operating in California, this settlement provides some clarity and relief, as the stringent ACF mandates will not move forward—at least for now. The trucking industry had long voiced concerns about the feasibility of meeting the ambitious targets for electric truck adoption and the financial strain that would have resulted from the forced transition.

However, the regulatory landscape surrounding zero-emission vehicles continues to evolve, with states like California still pursuing aggressive environmental goals. The legal battle over trucking regulations may not be over, and the industry will need to remain vigilant as future policies and rules are developed.

In conclusion, while the Advanced Clean Fleets rule is set to be repealed, the broader push toward zero-emission vehicles in the trucking sector remains alive, albeit with more scrutiny and legal challenges ahead. The outcome of this legal settlement will likely set a precedent for future attempts at regulating emissions in the transportation industry.

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