The Supreme Court is expected to announce this week whether or not it will hear the latest challenge to the Affordable Care Act—the King versus Burwell case. That case asks whether the Affordable Care Act should be taken literally. UPDATE: The court decided against hearing the challenge.

The ACA specifically grants insurance subsidies for policies bought on state exchanges. Now the question is: “Can the Internal Revenue Service say, ‘All right, even for people who’ve purchased insurance through the federal exchange, they can also get the tax credit,’” says Miller Baker, a partner at McDermott, Will and Emery.

Another big ACA case involves something called the Origination Clause, which requires all tax bills have to start in the House of Representatives. This case could face long odds.

“I believe that there has only been one successful Origination Clause case in history, and that was over a century ago,” says Timothy Jost, a professor at Washington and Lee University Law School. Jost says opponents of the healthcare law will have to prove it’s a tax bill. And he says it did originate in the House, but was overhauled in the Senate. 

There are other lawsuits that challenge specific aspects of the healthcare law—from contraception to the delay of the mandate for employers to insure their workers—but these aren’t likely to overturn it, experts say.