By Cherri Gregg

PHILADELPHIA (CBS) - The US Supreme Court could rule as early as today on whether all or part of President Obama’s healthcare law passes constitutional muster.

The Affordable Care Act gives nearly 1.3 million Pennsylvanians access to health insurance, says Antoinette Krause, Project Director at Pennsylvania Health Access Network. She says the law benefits small businesses, seniors, and individuals, including one often uninsured population– young adults.

“They graduate from college, they’re looking for a job, they get kicked off their parents plan because they are no longer in school. Or they get an entry-level job that doesn’t offer insurance,” says Antoinette Krause, Project Director at Pennsylvania Health Access Network.

The law allows young adults to stay on their parent’s plans through age 26.

“If the Supreme Court overturns the law, 64,000 young adults would be in danger of losing their health insurance.”

But University of Pennsylvania Law Professor Ted Ruger says no matter what the Supreme Court rules, undocumented or in some cases, legally present immigrants, still won’t get coverage.

“Despite all of what the statute does to expand access, there is still a gap in coverage. So in some sense, those folks are out of luck in the short-term, whatever happens with this statute.”

The Pew Hispanic Center estimates there are 160,000 illegal immigrants in Pennsylvania.