The California Air Resources Board (CARB) adopted emergency regulations aimed at restoring the state’s vehicle emissions standards following federal actions earlier this year that sought to block key elements of California’s clean vehicle program.
The emergency rule, approved and filed with the Secretary of State on October 2, 2025, is intended to preserve the existing regulatory framework pending ongoing litigation over Congress’s repeal of federal Clean Air Act (CAA) waivers supporting California’s Advanced Clean Cars II (ACC II) and Heavy-Duty Omnibus regulations.
Federal-State Conflict Over Clean Air Act Authority
The dispute centers on California’s longstanding authority under the Clean Air Act to set stricter vehicle emissions standards than federal requirements. That authority was challenged on May 22, 2025, when Congress adopted three resolutions disapproving of EPA waivers underlying California’s clean vehicle regulations.
Separately, the U.S. Department of Justice (DOJ) filed two complaints in August 2025 alleging that California’s emissions rules for light-duty and heavy-duty vehicles are preempted by federal law.
Emergency Rulemaking to Preserve Current Requirements
On September 13, 2025, CARB issued a Notice of Proposed Action for the emergency regulations 2025, allowing it to bypass standard rulemaking procedures. The emergency process allows the agency to avoid typical public notice and comment requirements if it determines that immediate action is needed to prevent harm to public health or welfare. CARB cited risks associated with increased air pollution as justification for expedited action.
The rule is designed to preserve emissions requirements that were in effect—or scheduled to take effect—prior to Congress’s disapproval of the waivers. CARB stated that federal actions and ongoing litigation have created uncertainty over which regulatory standards apply.
Industry Uncertainty and Compliance Risk
The overlapping federal and state actions have complicated compliance for automakers, fleet operators, and logistics companies operating in California and in states that have adopted California’s standards.
Because other states may elect to follow California’s emissions framework under the Clean Air Act, the outcome of the litigation could have nationwide implications for vehicle emissions policy and compliance obligations.
CARB’s emergency rule may stabilize near-term regulatory expectations within California, but it also raises the likelihood of further legal challenges from federal authorities and industry stakeholders.