EPA Restores California’s Clean Air Act Waiver, Allowing the State to Set Its Own Motor Vehicle Emissions Standards

On March 9, 2022, the US Environmental Protection Agency (EPA) rescinded a rule promulgated by the Trump Administration and revived California’s Clean Air Act waiver, allowing the state to set its own greenhouse gas emissions for cars and establish a zero-emissions vehicle program.

This move will effectively reinstate California’s Advanced Clean Cars Program, which has been adopted by California and opted into by 16 other states and the District of Columbia. The program regulates both smog-related pollutants and greenhouse gas emissions in new light- and medium-duty vehicles, with increasingly stringent regulations that apply currently through model year 2025 vehicles.


Section 209 of the Clean Air Act prohibits any state from adopting emissions standards more stringent than the federal Clean Air Act’s standards. However, the Section also includes a waiver provision that allows EPA to waive the prohibition so that a state may promulgate its own motor vehicle emissions standards in lieu of the federal standards. Such a waiver was granted for California’s Advanced Clean Car Program in 2013. That waiver was subsequently by the Trump Administration in 2019 through the Safer Affordable Fuel-Efficient Vehicles rule (the “One National Program Rule” or “SAFE-1”), setting off litigation on the issue.

Additionally, Section 177 of the Clean Air Act allows other states to adopt California’s motor vehicle emissions standards when a valid waiver exists and if such standards are identical to California’s. The SAFE-1 also interpreted Section 177 in a way that prevented other states from adopting California emissions standards, even with a valid Section 209 waiver in place.

The March 9, 2022, action by EPA reversed SAFE-1 “by finding that the actions taken under the previous administration as a part of SAFE-1 were decided in error and are now entirely rescinded.” EPA also withdrew the SAFE-1 interpretation of the Clean Air Act that prohibited other states from adopting California’s motor vehicle emissions standards. As a result, other states may choose to adopt and enforce California’s emissions standards in lieu of the federal standards.

Restoring California’s wavier and rescinding the previous interpretation of Section 177 are the Biden Administration’s latest steps to strengthen vehicle emissions standards, in addition to the administration’s recent finalization of a greenhouse gas emissions rule for cars and light trucks and a proposal to strengthen emission standards for heavy-duty vehicles and engines starting in 2027.


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