Bills have been introduced in the House of Representatives and Senate to repeal the authority of the Environmental Protection Agency (EPA) to grant waivers to California allowing the state to impose more stringent emissions requirements than under federal law.

The Clean Air Act generally preempts states from adopting or enforcing emission control standards for new motor vehicles or new motor vehicle engines. However, the Clean Air Act authorizes EPA to grant a waiver of preemption to California, and only California, to "meet compelling and extraordinary conditions." The waiver allows California to enforce more stringent standards than the federal requirements. In addition, another section of the Act allows other states to adopt the California regulations instead of following the federal EPA regulations applicable to emission control standards.

These are the provisions under which the EPA has granted waivers to the California Air Resources Board to adopt its Advanced Clean Trucks rule in 2023 and its Omnibus NOx rule in late 2024. An additional ten states have adopted CARB’s ACT rule as their state’s law. These are also the provisions under which CARB applied for, and later withdrew, a request for a waiver to adopt its Advanced Clean Fleets rule.

Senator Mike Lee (R-UT) has introduced the "Preserving Choice in Vehicle Purchases Act of 2025." The legislation prevents EPA from issuing a waiver to California if the waiver would directly or indirectly limit the sale or use of new motor vehicles with internal combustion engines. In addition, the bill would require EPA to revoke any waivers granted under the Clean Air Act since January 1, 2022.

On the House side, Rep. John Joyce (R-PA) has introduced H.R. 346, which has language and intent identical to the Senate counterpart bill.