California Governor Jerry Brown, a Democrat, signed a bill Friday that would allow as many as 390,000 undocumented adult residents to purchase their own insurance plans through Covered California, the state’s individual insurance marketplace under the Affordable Care Act.

But the Obama administration must approve a waiver for the first-of-its-kind law, which also bars the immigrants from receiving federal tax credits that would lower their premiums, before it can take effect, since Obamacare explicitly locks undocumented people out of the system.

Click here to subscribe to our new Brainstorm Health Daily newsletter.

“Today, we ask the federal government to remove barriers to health insurance access that discriminates against some of our residents on the basis of their documentation status,” said state Senator Ricardo Lara, the bill’s author, in a statement. “The current policy disallowing immigrants from purchasing care with their own money is both discriminatory and outdated.”

There are approximately 2.4 million undocumented immigrants living in California. And the state has been ramping up its efforts to offer them access to social insurance programs. For instance, California passed another first-in-the-nation bill last year allowing children to enroll in its Medicaid program irrespective of immigration status.

Supporters of the new law point out that it’s simply opening up an insurance market to undocumented immigrants who would be paying for their own coverage without government assistance. That could potentially take some pressure off the costly emergency rooms where many undocumented people are forced to receive medical care and boost California’s Obamacare market, since undocumented immigrants tend to be younger (and likely healthier) than the broader population.

Critics counter that the law encourages bad behavior and will put further financial strain on the Golden State’s medical sector.