Combustion bans: USA takes California to court
Are California's combustion bans legally effective? Daimler, Paccar, Volvo and VW are fighting it in court. Now the US government is getting involved.
Electric is certainly also possible. But does it have to?
(Image: Daniel AJ Sokolov)
The US government is involved in several court proceedings with the aim of having the emissions standards and combustion bans imposed by the US state of California declared invalid. In doing so, it is invoking federal law. California, in turn, considers a parliamentary resolution to be invalid and is also relying on a document signed by truck manufacturers in 2023.
As the current reason for the intervention, the US Department of Justice states that California is refusing to register new truck models until the manufacturer undertakes to comply with the Californian requirements – apparently regardless of whether the requirements have the force of law or not. The dispute over combustion bans itself is not new.
The starting point
The USA has federal emissions regulations. California wants to impose stricter requirements. This is permissible if the federal Environmental Protection Agency (EPA) grants California a corresponding permit. This has happened under previous US presidents. California repeatedly issued stricter regulations. These rules were then adopted by a number of other US states, which is generally permissible.
More recently, California has issued several regulations which, in addition to strict emission standards, also stipulate minimum quotas for the sale of locally emission-free new vehicles in the state. The conditions are gradually becoming stricter. From 2035, no internal combustion vehicles may be sold in California at all, and one year later no heavy vehicles (from around 3.6 tons) with an internal combustion drive.
The Clean Truck Partnership
Manufacturers of heavy-duty vehicles considered certain Californian requirements to be impractical. In 2023, California offered truck manufacturers some flexibility if the manufacturers contractually agreed to comply with California's requirements and waive any legal recourse. Even if courts were to declare the standards invalid, manufacturers would still have to comply with them. California did not back away from the 2036 truck combustion ban. The majority of the relevant heavy vehicle manufacturers signed the document called the Clean Truck Partnership.
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Three Californian regulations are at issue in the heavy vehicle sector. The EPA granted an exemption for one in 2023 and for the second only at the beginning of 2025, a few days before Donald Trump's second inauguration as US President. California applied for an exemption for the third regulation, but withdrew this application. The permit was therefore never granted.
Permission withdrawn
Trump and his party supporters are expressly opposed to combustion engine bans. Accordingly, this year the US legislature declared all exemptions for Californian emissions and sales restrictions null and void. This possibility is expressly provided for in the case of official acts that took place shortly before a change of government. If such a decision is made, the authority may not issue a new, similar act.
California considers the federal law to be inadmissible and is taking legal action against it. Meanwhile, the most populous US state is sticking to its regulations.
Industry associations and vehicle manufacturers filed lawsuits against California while Joe Biden was still in office. Two cases concerning cars and other light vehicles are currently pending before the US Court of Appeals for the Ninth Circuit. There, the US government is now requesting that the proceedings be discontinued. Their argument is that the statutory repeal of the exemptions renders the Californian emissions standards and combustion bans invalid, so there is no need for further litigation.
With regard to heavy-duty vehicles, a lawsuit by truck manufacturers Daimler, Paccar and Volvo as well as VW subsidiary International Motors is pending in the US Federal District Court for Eastern California. A second lawsuit by a chamber of commerce is pending in the US Federal District Court for Northern Illinois. The US government is now also intervening in both proceedings.
The US government's arguments
It argues that the "Clean Truck Partnership" document signed by truck manufacturers in 2023 is not in fact a reciprocal agreement, but merely regulation in disguise. The document itself speaks of regulation and lacks the usual contractual components. And the three truck regulations attached to the document as an annex are invalid.
For one of the three regulations, there had never been a waiver from the EPA; for the other two, they had been withdrawn by legislative decree. Moreover, federal law provides for a four-year lead time for new emission standards, regardless of any waivers, as well as a three-year standstill obligation on the part of the standard setter. The purpose of these provisions is to ensure that vehicle manufacturers do not have to reschedule every year; after all, they are preparing vehicle models and production facilities for the long term. California ignored these deadlines and only gave manufacturers two years' warning.
The Department of Justice, representing the USA in court, is requesting that both the Californian regulations and the document signed by the truck manufacturers be declared invalid. In addition, California is to be prohibited from issuing new emissions standards.
The case in the US Federal District Court for Eastern California is Daimler Truck North America et al v California Air Resources Board et al, Case No. 2:25-cv-02255.
The case in the U.S. District Court for Northern Illinois is American Free Enterprise Chamber of Commerce v Engine Manufacturers Association et al, Case No. 3:24-cv-50504.
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