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Supreme Court Ruling Allows Challenge of California’s Clean Air Act Waivers

Could a Supreme Court decision regarding a challenge to California's Clean Car standards eventually have implications for CARB's Clean Truck standards?

Deborah Lockridge
Deborah LockridgeEditor and Associate Publisher
Read Deborah's Posts
June 20, 2025
Supreme Court Ruling Allows Challenge of California’s Clean Air Act Waivers

Could the oil and gas industry sue California over electric truck mandates?

Image: HDT Graphic

2 min to read


The Supreme Court ruled on June 20 that fuel industry groups have legal standing to challenge the Environmental Protection Agency’s waiver that allowed California to implement its Advanced Clean Car I standards. Although this particular case involved the Clean Car standards rather than the Clean Truck standards, it’s another instance of challenges to California’s ability to set separate pollution standards.

The ruling comes just days after President Trump signed Congressional orders revoking EPA waivers issued during the Biden Administration for the Advanced Clean Cars II regulation, Advanced Clean Trucks regulation, and the Heavy-Duty Low-NOx Omnibus rule.

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The legality of Congress doing this under the Congressional Review Act is being questioned, and California and 10 other states immediately filed a lawsuit challenging what it said are "illegal resolutions targeting California’s clean vehicles program."

What Did the Supreme Court Decide?

This case was in regards to California's previous electric-car mandate, Advanced Clean Cars I. 

In Diamond Alternative Energy LLC v. EPA, Valero's Diamond Alternative Energy and other industry groups said the EPA's waiver approving the rules exceeded the EPA's power under the Clean Air Act and hurt the companies’ businesses by lowering demand for liquid fuels.

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In a 7-2 ruling, SCOTUS overturned a lower court's decision to throw out a lawsuit from fuel producers. The lower court had said the plaintiffs did not have the required legal standing to make the challenge. The Supreme Court disagreed, said the fuel producers do have standing, and sent the case back to the lower court to reconsider.

"The government generally may not target a business or industry through stringent and allegedly unlawful regulation, and then evade the resulting lawsuits by claiming that the targets of its regulation should be locked out of court as unaffected bystanders," conservative Justice Brett Kavanaugh wrote for the majority.

Liberal Justices Ketanji Brown Jackson and Sonia Sotomayor dissented. Jackson criticized the court for taking on the case when the Clean Car I rules are already ending in a few months.

Narrow Ruling Did Not Address Legality of CARB Rules

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, noted the Environmental Defense Fund in a statement.

“In fact, the Supreme Court declined review of a question challenging the constitutionality of the Clean Air Act provision authorizing California’s standards.”

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