What a Difference a State Makes: California’s Authority to Regulate Motor Vehicle Emissions Under the Clean Air Act and the Future of State Autonomy

Air pollutants from motor vehicles constitute one of the leading sources of local and global air degradation with serious consequences for human health and the overall stability of Earth’s climate. Under the Clean Air Act (“CAA”), for over fifty years, the state of California has served as a national “laboratory” for the testing of technological solutions and regulatory approaches to improve air quality. On September 19, 2019, the Trump Administration revoked California’s authority to set more stringent pollution emission standards. The revocation of California’s authority frustrates ambitious initiatives undertaken in California and in other states to reduce local air pollution and mitigate the effects of climate change from mobile sources. This Article argues that the reasons offered by the Administration to justify its rollback of California’s authority are not persuasive. They do not find support in the history and longstanding interpretation of the CAA, in the Environmental Protection Agency’s implementation practice, or in the regulated industry, and, coupled with halting the rise in federal fuel economy standards, constitute unsound policy at a crucial moment for greenhouse gas emissions mitigation. In addition, this Article advances the idea that instead of aiming to suppress California’s experimentation with zero emissions vehicles, current and future Administrations should embrace new ways to cooperate with California and a growing number of states that have begun thinking creatively about reforming the transportation sector. By building on a flexible and multilevel model of governance, grounded on forms of cooperative federalism that leverage state innovation and regulatory expertise, the federal government together with the states will ensure a more competitive future for America.