California’s Clean Air Act waiver faces Supreme Court test

By Lesley Clark | 04/21/2025 06:33 AM EDT

The high court this week will hear arguments on whether opponents have standing to challenge the state’s right to set tough pollution rules.

Environmental activists rally in front of the Supreme Court.

Environmental activists rally in front of the Supreme Court on July 6, 2022. Drew Angerer/Getty Images

The outcome of an upcoming Supreme Court case could accelerate efforts to roll back California’s authority to set the nation’s toughest rules on tailpipe emissions — just as the Trump administration seeks to curtail states’ abilities to tackle climate change.

The Supreme Court on Wednesday will hear a challenge to the state’s long-standing Clean Air Act waiver that allows it to establish pollution limits for cars and trucks that are stricter than the federal government.

The arguments in Diamond Alternative Energy v. EPA won’t center on the waiver itself, which oil and biofuel interests had sued over. Instead, the court in December agreed only to take up a procedural issue: whether the petitioners have legal standing to bring a lawsuit that challenges EPA’s authority to grant California such power.

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Standing — or who has the power to bring lawsuits — is a major issue in environmental litigation. If courts take a narrow view of standing, they can effectively shut down environmental lawsuits before they begin.

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