Last week, NACS won its U.S. Supreme Court case, giving it the ability to challenge the state of California’s Advanced Clean Cars I rule.

In December 2024, NACS and its coalition partners filed a petition in the Supreme Court in a case challenging the rule. The California rule set standards requiring 22% of new vehicles sold in the state to be “zero emission” in model year 2025. The rule is a precursor to later California rules that over time would require 100% of new vehicles sold in California to be “zero emission.”

The DC Circuit Court of Appeals had previously ruled against NACS on the grounds that automakers would do the same thing regardless of whether the rules were in place. In the court’s view, that left NACS and its partners without any legal complaint because invalidating the rule would not help them, leading the Supreme Court to consider whether that was the correct reading of the law and whether the case can proceed to the ultimate question of the legality of EPA’s waiver for California.

NACS argued that its members were harmed by the rule as written and the entire intent of the rule was to reduce the sale and use of motor fuel.

“We are pleased that the Supreme Court rejected California’s attempt to hide behind a hollow legal technicality,” said Doug Kantor, NACS General Counsel. “Everyone knows that by mandating specific vehicle technologies, the California rule limits the cars that could be bought in California and other states. If the rule had no impact, as California argued, there would be no reason for it to defend the rule in Court. The state’s own actions showed our coalition was right to bring this case.”

For California to set its own rules, it must be granted a waiver to do so by the U.S. Environmental Protection Agency (EPA). Those waivers are supposed to be based upon the specific air quality needs in California. Instead, California asked for a waiver based on its concern about global climate change, not California-specific air quality. NACS, coalition partners in the traditional and renewable fuels industries, and several other states filed challenges to the waiver on the basis that global issues must, under the law, be addressed by national standards.

NACS had concerns and presented evidence that picking one technology over others leads to worse outcomes for the environment and the economy.

NACS now has the chance to try to overturn the California Advanced Clean Cars I rule as the case is sent back to the trial court.