California is toughening its auto emissions standards at a time when nationwide requirements seem likely to be loosened.
The California Air Resources Board requires automakers to make sure 15 percent of their sales are zero-emission vehicles by 2025.
Typically, the federal government decides that level, but thanks to a waiver in the Clean Air Act, California sets its own standard. That's a big deal because 12 other states have set their levels to match California.
Environmentalists hailed the decision as a big win, but it may not last. President Donald Trump promised to cut regulations after carmakers said they were being forced to sell an unreasonable percentage of zero-emission vehicles.
The disagreement could set the stage for a court battle between California and the Trump administration. Gov. Jerry Brown has promised to fight Trump's agenda, hiring former Attorney General Eric Holder to bolster the state's legal defense.