Documents outlining the EPA's plan to roll back vehicle emission standards reference California by name 27 times.

California and environmental groups fiercely criticized the EPA's plans to undo the endangerment finding that enables greenhouse gas regulation.

That assessment followed a 2007 U.S. Supreme Court decision in its landmark Massachusetts v. EPA case that said the EPA has the authority under the Clean Air Act to regulate greenhouse gas emissions and required the agency to make a scientific finding on whether those emissions endanger public health.

Stringent tailpipe emissions and mileage rules were part of the Biden administration's pledge to clean up the nation’s vehicles and reduce use of fossil fuels by incentivizing growth in EVs. EVs do not use gasoline or emit greenhouse gases.

The Trump administration has effectively eliminated two rules designed to promote cleaner cars. Now, as the EPA suggests not considering carbon dioxide to be pollution, the last is poised to fall.