The U.S. Department of Justice (DOJ) filed two lawsuits on August 15, 2025, aiming to block California from enforcing its stringent emissions standards for heavy-duty trucks. The legal action marks a sharp turn in the long-running battle between federal and state authority over climate policy.

At the heart of the lawsuits is the Clean Truck Partnership, a 2023 initiative between the California Air Resources Board (CARB) and major truck manufacturers. The program was designed to reduce emissions while offering manufacturers flexibility. However, the DOJ now argues that California no longer has legal authority to impose such standards after President Donald Trump and Congress formally revoked the Clean Air Act waivers that enabled them.

The lawsuits claim that CARB staff are preventing truck manufacturers from bringing vehicles to market unless they comply with these now-preempted state rules. "This ongoing defiance of federal law must stop," the DOJ stated, signaling a more aggressive posture under the Trump administration.

Filed as motions to intervene in two existing federal cases-one in Sacramento, California, and another in Rockford, Illinois-the lawsuits are supported by major players in the trucking industry, including Daimler, International, Paccar, and Volvo, along with the American Free Enterprise Chamber of Commerce.

Adam Gustafson, acting assistant attorney general for the DOJ's environment and natural resources division, emphasized that the Clean Air Act waivers have been invalidated, stripping CARB of the legal basis for enforcement. "CARB must respect the democratic process," he said.

While California has historically leveraged federal waivers to set stricter-than-national air quality standards-receiving over 100 since 1970-the current administration argues those days are over. Trump's June approval of congressional resolutions invalidated several waivers, including the one underpinning the Clean Truck Partnership.

Governor Gavin Newsom, a Democrat and vocal supporter of climate-focused transport policy, has not commented publicly. CARB also declined to respond to requests for comment.

The litigation has broad implications beyond California. If the DOJ succeeds, it could reshape how states influence emissions policy, particularly regarding the transition to electric and low-emission vehicles.

For professionals in agriculture, logistics, and heavy transport, the stakes are high. The outcome may directly affect truck fleet standards, input costs, and long-term investment in sustainable transport infrastructure across the U.S.