In a policy reversal, the California Air Resources Board (CARB) has agreed to formally repeal aspects of its Advanced Clean Fleets (ACF) regulation, which aimed to transition medium- and heavy-duty trucks to 100% zero-emission vehicles. This decision follows CARB’s earlier withdrawal of its waiver request to the U.S. Environmental Protection Agency (U.S. EPA) in January 2025 which, in effect, halted enforcement of the High-Priority Fleet and Drayage requirements of ACF.
Now, in response to legal challenges from a coalition of 17 states led by Nebraska and trucking industry groups, CARB has agreed to fully repeal those portions of the rule and has further clarified it will not enforce the 100% zero-emission sales mandate for model year 2036, until and unless CARB obtains a waiver from U.S. EPA. This agreement and change does not impact CARB’s authority or enforcement of ACF’s State and Local Government Fleets requirements, which remain in effect.
The regulation has faced significant opposition from trucking industry stakeholders. In October 2023, the California Trucking Association filed a lawsuit against the state, arguing that the ACF rule would impose undue burdens on the trucking industry. Subsequently, in May 2024, Nebraska Attorney General Mike Hilgers led a coalition of 17 states in a lawsuit challenging the regulation, asserting that it would disrupt interstate commerce and strain supply chains.
The plaintiffs contended that the ACF regulation, by leveraging California’s significant market size and access to international ports, effectively imposed its standards nationwide, thereby violating the Commerce Clause and overstepping federal authority under the Clean Air Act.
As part of a legal settlement, CARB agreed to initiate the process of repealing the High-Priority Fleet and Drayage Fleet requirements of the regulation. The agency is expected to propose the formal repeal by October 31, 2025, with final action required by August 31, 2026. Until then, California is barred from enforcing any part of those aspects of the rule.
Nebraska Attorney General Mike Hilgers hailed the settlement as a victory for the state’s logistics industry and consumers.
“This settlement is a huge win for everyone in Nebraska, from our outstanding logistics industry that is critical to the Nebraska economy, for consumers who would have faced higher prices, and for the rule of law,” he said.
