California, along with 16 other states and the District of Columbia, have formally launched a long-anticipated lawsuit against EPA over its proposed rollback of emissions rules for 2022 through 2025, according to a new report in the Washington Post.

The suit was filed last month in the D.C federal appeals court in response to EPA Administrator Scott Pruitt's announcement last month that he would rescind the Agency's 2016 decision to maintain standards through those model years, made during the "mid-term review" [PDF] of the standards, which was originally scheduled to happen in 2017. 

The standards were initially supposed to ramp up to 54.9 mpg by 2025, counting all cars and trucks sold in the United States. Following Pruitt's decision last month to reopen the mid-term review with an eye toward lowering the standards, a leaked memo reports that the leading proposal under consideration would cut off future increases at levels set for 2021, at 42 mpg.

EPA administrator Scott Pruitt [photo from 2014]

EPA administrator Scott Pruitt [photo from 2014]

Since the Supreme Court decided in 2007 that carbon dioxide qualifies as a pollutant that the EPA must regulate, emissions standards have also come to govern fuel economy, since there is no way to reduce CO2 without reducing fuel consumption.

Automakers lobbied the EPA and the National Highway Traffic Safety Administration to loosen the rules, saying they were too difficult to meet now that consumers have begun buying such a large preponderance of trucks and SUVs. 

Detractors have argued that the standards would hurt car sales and reduce American jobs. So far, the higher standards through 2017 have had no negative effect on car sales or employment in the auto industry, as some detractors had anticipated.

Mary Nichols, chief, California Air Resources Board

Mary Nichols, chief, California Air Resources Board

Speaking for the states filing suit, California Air Resources Board chairwoman Mary Nichols issued a statement, saying:

"The standards we are fighting to protect were adopted in 2012 and don't take effect until 2022. They were a lifeline thrown to an industry that was in trouble and desperate for stability. they were based on the best judgment of engineers about what technology could achieve. And in fact they are being achieved today, years ahead of the deadlines, because of the good work of the auto industry.

"But now Administrator Pruitt, based on no new information or facts, wants to roll back all that progress in the name of deregulation. The final determination is just the first step, but it is intended to provide the legal basis for a decision that has already been made: to halt the progress that regulators and industry have made toward a new generation of vehicles. It does not withstand scrutiny, and it will not stand."

The draft proposal also suggests that the EPA will try to circumvent the right that California has been afforded for nearly 50 years to set its own emissions standards.

The lawsuit had been anticipated since Pruitt's decision to reverse the findings of the mid-term review was announced.