Could California’s entire set of vehicle emission standards, including its zero-emission vehicle program that has helped launch the global electric vehicle market, come under federal assault?  It’s a worst-case scenario that would require congressional action, but it’s amazingly within the realm of possibility.

California has unique authority under the federal Clean Air Act to regulate vehicle emissions.  That authority requires the state to first seek a “waiver” from less-stringent federal standards from the U.S. Environmental Protection Agency.  The EPA always granted those waiver requests until the George W. Bush administration came along.  His administration refused to grant a waiver for the state to regulate greenhouse gas emissions from tailpipes.

California sued, but the Obama Administration took office before the case was resolved and then granted the waiver.  But now new EPA administrator Scott Pruitt is looking not only to refuse to grant future waivers but possibly roll back previously granted ones (Buzzfeed covered the issue on Tuesday with some quotes from yours truly).  It would be an unprecedented step that would be sure to be challenged in court.

But the even deeper concern is that the litigation might prompt Congress to revoke California’s waiver authority altogether.  The Atlantic has a great piece on the situation, including this passage quoting Debbie Sivas at Stanford:

She feared that this fight in the courts would accompany a political fight in Congress, as the administration would seek to amend the Clean Air Act to remove California’s waiver power before they lost the lawsuit.

And—almost in preparation for that battle—she asked Americans to take a step back and examine why regulating greenhouse gases from cars is important.

“It feels like this very technical thing about, ‘blah blah, waivers, blah blah blah,’ but it’s a very important part of the climate policy,” Sivas told me. “People aren’t going to stop driving, really. And transportation’s 40 percent of carbon emissions. The only way to get [those emissions] down is to get [fuel] mileage up. If the feds are going to take their foot off the gas—and to fight the states who are doing it—it could be a huge setback,” said Sivas.

There’s a lot at stake in this fight. Federal fuel economy standards are prompted by California’s authority on the issue, and future standards could definitely be at risk. I have a lot of confidence in California’s legal team to fight this assault, but it would be a major setback for the time being.

But if Congress were to revoke the waiver status, and even retroactively apply it, the future of both cleaner gas-powered cars and the nascent electric vehicle market would be at tremendous risk.