The U.S. Supreme Court is set to hear a challenge from fuel companies against California’s ability to create its own emissions rules, in a case that could set a major precedent for how states handle making their own standards in efforts to lower greenhouse gas emissions through electric vehicle (EV) adoption.

After the Environmental Protection Agency (EPA) granted California an exemption from federal air pollution laws in 2022, effectively letting the state set its own vehicle emissions rules, the U.S. Supreme Court last week agreed to listen to a bid from a Valero Energy subsidiary and other fuel groups to challenge the exemption (via Reuters).

Valero’s Diamond Alternative Energy and other associated fuel business lobby groups argue that the waiver oversteps the power of the EPA under the Clean Air Act, under which the federal rules are set. The groups also argued that such a decision would lower demand for their liquid fuels, ultimately inflicting harm on their bottom line.

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In the appeal, the groups also said that California was overstepping its power, acting as a “junior-varsity EPA” by making regulatory decisions to combat climate change and force the adoption of EVs upon consumers—choices the group says the state does not have the right to make.

The decision also comes after the EPA was backed by the U.S. Court of Appeals for the District of Columbia in April, with the court throwing out a legal challenge against the waiver from a group of 17 Republican-run states. In that appeal, backers also argued that California’s ability to set its own emissions rules gave the state unconstitutional regulatory power, which they said isn’t available to other states.

The waiver has long been a point of contention, originally dating back to a 2013 decision to offer California the waiver. In 2019, the Trump administration rescinded that waiver, before the EPA was given power to reinstate it under the Biden administration in 2022.

California has also been a leader in pushing EV adoption through massive incentives, and an official ruling later in 2022 to ban the sale of new gas cars beginning in 2035. That ruling has since been followed by a handful of other states, including New Jersey, New York, Oregon, and Washington.

Last year, California’s battery-electric vehicle (BEV) sales also made up around one-third of all U.S. BEV sales, as led by Tesla.

Passed by the California Air Resources Board (CARB), the California ban also includes a gradual phase-out of gas vehicles set to begin in 2026, for which the state also required an EPA waiver. California has gained over 75 separate waivers since 1967, through which it has been able to lodge increasingly strict rules surrounding vehicle emissions performance and EV sales.

In February, the EPA actually loosened federal standards requiring automakers to sell a certain ratio of EVs by 2032. Previously, the agency required that automakers make 60 percent of sales come from BEVs and plugin hybrids by 2030, increasing that to 68 percent by 2032. Now, the agency mandates that manufacturers make 50 percent of their overall sales either plugin hybrids or BEVs by 2030.

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