The lawsuit, filed in the U.S. District Court for the District of Columbia Circuit, marks the latest round of an escalating battle between the White House and California officials about how quickly the nation's car fleet must increase its fuel efficiency. Already, the feud has led to several legal meetings, a shared car industry and uncertainty in the country's car market.
In mid-September, the Trump administration acted to revoke California's decades-old ability to set air pollution standards for cars, pickups and SUVs that go beyond what is required by the federal government. California's authority to set such standards goes back to the Clean Air Act of 1
The administration's move was a high-profile example in a broad campaign to undermine the Obama-era policy of cutting greenhouse gas emissions that provide fuel for climate change.  When asked about the lawsuit on Friday, EPA spokeswoman Molly Block said the agency was not commenting pending litigation. But she said the administration had the right to go ahead with the revised mileage standards and make "clear that federal law prevents state and local emissions standards for greenhouse gases" as well as zero-emission vehicles.
"This action will help to ensure that there will be one, and only one, set of national standards for fuel economy and greenhouse gas emissions for vehicles," Block added.
Within a few days, California and 22 other states, along with several cities, brought a federal lawsuit against the National Highway Traffic Safety Administration. That case argued that efforts to prevent California from setting more ambitious emissions standards "exceed NHTSA's authority, contravene Congressional intent and are arbitrary and capricious, and because NHTSA has failed to perform the analysis required by national environmental law. "  The recent filing in the DC Circuit also includes a petition asking the court to review NHTSA's attempt to prevent California's right to set emission standards for pipes. The Attorneys Generals of Colorado, Connecticut, Delaware, Hawaii, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, Nevada, New Jersey, New Mexico, New York, North Carolina, Oregon, Pennsylvania, Rhode Island, Vermont, Virginia, Washington State of Wisconsin and the District of Columbia joined California in filing lawsuits, along with the cities of Los Angeles and New York.
The current standoff began last year when the NHTSA and EPA jointly submitted to the Trump administration's proposal last year to repeal California's "waiver" as part of a rule that would freeze mileage standards for these vehicles to about 37 miles per gallon from 2020 to 2026. The Obama-era standards had required these fleets to average almost 51 mpg by the year 2025.
July, California forged a deal after months of secret negotiations with four companies – Ford, Honda, Volkswagen and BMW in North America – where they committed to produce fleets on average nearly 50 mpg after model year 2026. The Department of Justice has opened an investigation into whether it passed violations of the antitrust law.
The episode has exposed a rare political rift in the automotive industry – one that can throw powerful car manufacturers' industrial giants against each other in a protracted legal battle.
Emissions from the transportation sector, including cars and trucks, now rank as the largest single source of greenhouse gases in the United States.
And while some of the biggest car manufacturers have now backed the Trump administration in its legal battle with California, Americans seem to support stricter mileage goals. A Washington Post-Kaiser Family Foundation released in September found that 66 percent of Americans oppose Trump's plan to freeze fuel efficiency standards instead of enforcing the Obama administration's 2025 goal.
An almost identical 67 percent majority said they supports state governments that set stricter fuel efficiency goals than the federal government. Among Californians, the poll found that 68 percent oppose Trump's easing of mileage standards, while 61 percent support California's stricter standards.
Currently, 13 states and the District of Columbia have promised to comply with California standards if they deviate from the federal government. The move could plague car manufacturers for a long period of uncertainty and create turmoil in the country's car market.