U.S. Sues California Over EV Mandates, Escalating Battle Over Vehicle Emissions Rules

The Trump administration has filed a lawsuit against California, challenging the state’s ambitious zero-emission vehicle (ZEV) mandates and greenhouse gas limits for cars and trucks, in the latest escalation of a long-running federal-state clash over climate policy.

The legal action, brought by the U.S. Department of Transportation against the California Air Resources Board (CARB), argues that California’s rules are preempted by federal law and therefore unlawful. The case was filed in federal court and seeks a ruling declaring the state’s zero-emission vehicle mandates unenforceable.

At the center of the dispute are California’s vehicle standards requiring automakers to steadily increase sales of electric vehicles and comply with stricter tailpipe emissions limits. The state’s long-term plan aims to phase out the sale of new gasoline-powered cars by 2035 under its Advanced Clean Cars II framework.

Federal officials argue the state’s policies create conflicting regulatory regimes for automakers. Jonathan Morrison, head of the National Highway Traffic Safety Administration, said the lawsuit would help manufacturers design vehicles under a single nationwide fuel economy standard.

California officials, however, dismissed the lawsuit as meritless. A spokesperson for Governor Gavin Newsom said the state would continue pursuing policies that promote cleaner vehicles and reduce dependence on volatile global oil markets.

California has historically been granted special authority to set stricter vehicle emissions standards due to its severe air pollution challenges. In 2022, the U.S. Environmental Protection Agency approved the state’s earlier rules known as Advanced Clean Cars I, which California maintains are still in force.

The lawsuit follows other federal actions targeting California’s climate policies. The administration previously challenged the state’s stricter emissions standards for heavy-duty trucks and supported congressional efforts to revoke California’s authority to ban gasoline-powered vehicle sales after 2035.

The dispute reflects a broader policy divide over the future of U.S. transportation. While California argues that stronger EV mandates will lower long-term fuel costs and cut emissions, the federal government has moved to weaken national fuel economy and tailpipe rules, setting up a potentially prolonged legal battle over the direction of American climate and automotive policy.

Federal litigation against California EV mandates escalates the state-versus-federal conflict that shapes US auto-industry planning, and it directly affects how OEMs and suppliers should structure fleet-electrification bets. Our energy-transition and market-intelligence teams help clients build multi-scenario planning that stays robust across federal-state divergence.