California is suing the Trump administration over its efforts to overturn the state's vehicle emissions rules.
The lawsuit centers on four Clean Air Act waivers. They allow California to set stricter emissions standards than the federal government, including rules on greenhouse gas emissions from cars and on small engines like leaf blowers and lawn mowers.
For more than 50 years the Environmental Protection Agency has treated these waivers as orders. This month the agency reclassified them as rules, allowing Congress to vote to overturn them.
Attorney General Rob Bonta said undoing the waivers would have wide-reaching effects.
"It would mean more pollution," Bonta added, "poorer air quality, greater health risks for communities already burdened by emissions, and increased uncertainty in the clean vehicle industry."
The EPA says the emissions rules raise costs for consumers.
This is the state's 72nd lawsuit against the Trump administration.