The fate of Obamacare could reside in the hands of one of these 2 people

The fate of the Affordable Care Act is in the hands of the Supreme Court once again - and whether it lives as is or crumbles might depend on a justice who believes the heart of the law to be unconstitutional.

Justice Anthony Kennedy is the traditional swing vote, and his views on the latest death threat to the law colloquially known as Obamacare will likely predict how the court rules.

The fate of the decision could also rest with conservative Chief Justice John Roberts, who previously sided with the liberals to uphold the law.

This latest challenge puts Kennedy in a particularly vexing position.

Just three years ago, he voted against the government and opined that the heart of the Affordable Care Act - its individual mandate requiring individuals to purchase some form of health insurance or pay a penalty - was unconstitutional. Kennedy read his dissent from the bench with a palpable display of emotion after Roberts joined the liberals to save the law.

"It amounts to a vast judicial overreaching," Kennedy said of the 5-4 decision that upheld the mandate's penalty as a tax.

Now Kennedy might be the one to save a key provision of the law. This challenge, King v. Burwell, has the potential to cripple the law and throw its future into highly uncertain territory in the 36 states where the federal government provides subsidies for low-income people to buy health insurance.

The high court's decision could be handed down as soon as Monday and is expected to be delivered sometime before the end of the month. And again, Kennedy and Roberts are the justices to watch.

"They're going to be the swing votes," said Jonathan Adler, a professor at Case Western University School of Law and one of the lawyers instrumental in forming the challenge.

"And I expect them to vote together, whichever way they vote."

The challengers in King v. Burwell are focusing on four words in the statute that supposedly suggest the federal government can't subsidize health insurance in the 36 states that refused to set up their own exchanges. Those four words are in Section 1311 of the law, which establishes insurance exchanges. That section states that subsidies should be issued to plans purchased "through an Exchange established by the State under Section 1311" of the Affordable Care Act.

Kennedy was the justice targeted by both the challengers and the Obama administration during oral arguments in March. And each side saw points in which they thought he was leaning their way. In one exchange, he seemed to worry about the coercing effects a decision against the healthcare law would have on states to set up their own insurance marketplaces.

During another, he said the challengers "may prevail" on the "plain words of the statute," even though he acknowledged a "serious constitutional problem if we adopt your argument."

Chris Walker, an assistant professor at the Michael E. Moritz College of Law who clerked for Kennedy, told Business Insider that Kennedy could go either way.

"A lot of the questions he was asking were about federalism, and federalism is something he cares deeply about," Walker said.

On the flip side, near the end of the oral argument, Kennedy asked Solicitor General Donald Verrilli - who represents the Obama administration - about how much authority the IRS should have in interpreting a law passed by Congress, as Slate's Dahlia Lithwick noted. It was the IRS that interpreted the law to allow subsidies in states with exchanges set up by the federal government.

Kennedy questioned whether Congress really meant for the IRS rather than the states to make a decision with potentially billions of dollars at stake.

"[I]t seems to me a drastic step for us to say that the Department of Internal Revenue Service and its director can make this call one way or the other when there are, what, billions of dollars of subsidies involved here? Hundreds of millions?" Kennedy said during the oral arguments.

"So you've got these bookends," Walker told Business Insider. "At the beginning, he seems very concerned about the federalism argument. And at the end of the argument, he seems to be concerned about executive power and congressional interpretation. So it's difficult to figure out where he stands."

Roberts is much harder to figure out, and Supreme Court observers say they're entirely uncertain which way he'll lean. On one hand, he upheld the law last time. On the other hand, he's viewed as generally pro-business in his decisions, and multiple businesses and organizations have issued briefs on the side of the administration in this case.

Complicating things is the fact that Roberts spoke just two meaningful times during the oral arguments. That was as often as the number of times he opened his mouth to crack a joke at one of the lawyers involved in the case.

Kennedy has been more of a talker. In fact, just three weeks after the arguments, he appeared before Congress and said something that some observers viewed as possibly tipping his hand. He said, in a general sense and without mentioning the Affordable Care Act, that the judiciary should decide cases without worrying about external factors like congressional gridlock.

That comment spurred speculation that he might not have any qualms about dismantling Obamacare even though lawmakers might not ever come together to fix the law.

But even Adler, one of the legal minds behind the King challenge, said those comments didn't raise his hopes.

"Those comments in Congress were normal," Adler said. "I don't think anyone thinks the court's decision will be affected by Congress."