Supreme Court Will Not Consider Constitutional Challenges to California Clean Vehicle

(Washington, D.C. – December 16, 2024) The U.S. Supreme Court today denied a petition asking it to review constitutional challenges to California’s authority to enforce its own pollution limits for new cars and passenger trucks.  

The Court’s order denying a petition submitted by Ohio and other states comes after the Court on Friday declined to consider the merits of oil and gas interests’ separate challenges to the lawfulness of EPA’s decision granting California a waiver of Clean Air Act preemption for its clean vehicle standards. The only issue the Court will consider related to these challenges is a narrow, threshold question concerning whether oil and gas interests had standing to bring their claims; the Court granted review on that issue in its Friday order.   

“California’s clean car standards have successfully helped reduce the dangerous soot, smog, and climate pollution that put all people at risk, while also turbocharging clean technologies and job creation,” said Alice Henderson, Director and Lead Counsel for Transportation and Clean Air Policy for Environmental Defense Fund. “EPA’s decision to grant California this preemption waiver is based on a rock-solid legal foundation and decades of precedent, and it ensures vital clean air protections for millions of people.”

California's emissions standards have played a central role in many life-saving advancements in vehicle emission technology, from catalytic converters to zero-emission vehicles. Congress has long recognized California’s leadership in addressing the harmful pollution from new vehicles and adopted Clean Air Act provisions specifically excluding California’s standards from preemption.  

Since 1967, the Clean Air Act has contained a preemption waiver for California’s emission standards for new motor vehicles, so long as those standards are at least as protective as national standards. In that time EPA has granted California more than 75 waivers. The California clean cars program at issue in this case has been delivering life-saving pollution reductions to communities since 2017 and has been adopted by 17 other states across the country.  

In 2023, the oil and gas industry as well as the attorneys general of Ohio and other states challenged this waiver. The state challengers were not seeking their own right to set standards – they just wanted to disrupt California’s longstanding clean cars program. In April 2024, a  panel of judges on the U.S. Court of Appeals for the D.C. Circuit ruled against the challengers and upheld EPA’s decision to grant the waiver to California, unanimously rejecting the challengers’ constitutional argument. EDF was part of a coalition of environmental and health groups that helped defend the waiver as parties in that case. California, joined by 18 other states and the District of Columbia, and a group of major auto manufacturers including Ford, Honda, Volkswagen, BMW, and Volvo, also intervened to defend EPA's decision. 

The challengers then filed petitions with the Supreme Court asking it to review the D.C. Circuit's decision. Today, the Court denied Ohio’s constitutional challenges to California’s authority, though Justice Thomas did indicate he would have granted review. On Friday, the Court denied oil and gas interests’ separate petition seeking review of the lawfulness of EPA’s decision to grant California the waiver. The Court did grant review limited to a narrow question about fuels companies’ standing to bring their claims. 

“EDF is committed to continuing to help defend California’s Clean Air Act authority and these life-saving clean car standards,” said Henderson. 

You can find all legal briefs in these cases, and other cases challenging clean car and truck standards, on EDF’s website.