Supreme Court Ruling Does Not Address Merits of California Vehicle Standards, Does Determine that Fuel Industry Has Standing to Challenge Them

(Washington, D.C. – June 20, 2025) The Supreme Court ruled today that fuel industry groups have legal standing to challenge EPA’s preemption waiver for California’s Advanced Clean Car I standards. In doing so, the Court rejected petitioners’ invitation to adopt a broad and categorical standing rule, and instead —consistent with its longstanding practice — based its decision on the specific facts of this case.   

The ruling was in Diamond Alternative Energy LLC v. EPA. Environmental Defense Fund intervened in the lower court in support of California's standards.

The case did not address California’s longstanding Clean Air Act Authority or the merits of the state’s Advanced Clean Car I standards, which are unaltered by the Court’s decision and remain in full force and effect. In fact, the Supreme Court declined review of a question challenging the constitutionality of the Clean Air Act provision authorizing California’s standards, which means the U.S. Court of Appeals for the D.C. Circuit decision rejecting those constitutional challenges stands.

“The state’s affordable clean car standards are vital safeguards for Californians and for people in the 17 other states that have adopted the program – people who are suffering from severe smog and soot and from the deadly fires, heatwaves and storms caused by climate change. The standards have saved hundreds of lives, have provided enormous health benefits, and have saved families money,” said EDF General Counsel Vickie Patton. 

“California’s authority to protect people from vehicle pollution is enshrined in our country’s foundational environmental laws and has been working successfully for more than half a century. The U.S. Court of Appeals for the D.C. Circuit unanimously rejected challenges to this EPA preemption waiver, and the Supreme Court agreed to reconsider only one small part of those challenges – the narrow question of legal standing that it decided today,” said Patton. “While the Supreme Court has now clarified who has grounds to bring a challenge to court, the decision does not affect California’s bedrock legal authority to adopt pollution safeguards, nor does alter the life-saving, affordable, clean cars program itself.”