The U.S. Environmental Protection Agency rejected Obama-era fuel efficiency standards and set the stage for a battle with California clean air regulators.
In a reference to the special exemption that allows California to set tougher emissions standards than the federal government does, EPA Administrator Scott Pruitt said, "cooperative federalism doesn't mean that one state can dictate standards for the rest of the country."
Twelve other states join California in adopting tougher emissions standards, leading automakers to adopt the more stringent requirements rather than make cars for two different standards.
California Air Resources Board Chair Mary Nichols issued a statement saying, "this decision takes the U.S. auto industry backward."
It looks like the Trump administration and California are speeding towards another court battle, this time over emissions standards.