The United States Justice Department took legal action against the state of California on Thursday, contesting the state's stringent emissions regulations. The lawsuit specifically targets the California Air Resources Board’s (CARB) "Clean Truck Partnership," which aims to transition heavy-duty truck manufacturers to electric vehicles by 2036. The federal challenge comes in two parts: one concerning heavy-duty trucks and the other addressing light-duty vehicle guidelines.
Acting Assistant Attorney General Adam Gustafson, who leads the Justice Department’s Environment and Natural Resources Division, criticized the regulations as an overreach of power. "Agreement, contract, partnership, mandate — whatever California wants to call it, this unlawful action attempts to undermine federal law," Gustafson stated. He referenced the invalidation of Clean Air Act waivers under President Donald Trump and Congress, which served as the foundation for California's emissions policies.
The legal dispute aligns with actions taken by several truck manufacturers, including industry giants Daimler and Volvo. These companies have expressed opposition to the state's emissions rules, arguing that they impose unfair operational restrictions and could lead to significant financial penalties for non-compliance.
California had initially obtained federal approval under the Biden administration to enact its stricter emission standards. However, a shift occurred when President Trump signed congressional resolutions in June 2025, revoking those waivers and preventing the state from implementing rules more stringent than the federal government's.
The Justice Department's lawsuit contends that without the waivers, the Clean Air Act bars CARB from enforcing the preempted emissions standards, yet the state continues to do so through the Clean Truck Partnership. The suit also argues that California’s actions could result in a de facto national ban on internal-combustion engines in heavy-duty trucks by 2036, a decision that should rest with the federal government.
The Justice Department emphasizes that CARB is threatening non-compliant manufacturers with civil sanctions and adverse regulatory treatment. This lawsuit underscores the ongoing conflict between state environmental initiatives and federal authority, particularly under Trump's administration, which advocates for a more business-friendly and less regulatory approach compared to the previous Biden administration.
Officials argue that federal law preempts state efforts that exceed national standards, and by enforcing stricter rules without federal approval, California is allegedly overstepping its legal authority and disrupting the uniform application of environmental policy.
This lawsuit is poised to become a pivotal conflict over state-versus-federal power concerning environmental regulations and electric vehicle mandates. Manufacturers, industry groups, and political stakeholders are closely observing the case, which has the potential to significantly influence the future of emissions policy in the United States.
While CARB has not yet publicly responded to the lawsuit, the Trump administration's move is a clear indication of its intent to assert federal control over emissions rules and prevent states from implementing aggressive climate mandates that extend beyond federal law.
