Despite predictions that King v. Burwell, the Obamacare challenge, was a done deal, a reading of the tea leaves in today’s oral arguments at the Supreme Court suggests the opposite: that Obamacare will survive.

The reason? A canon of constitutional interpretation well known to lawyers, but little known to everyone else.

Let’s go to the (nonexistent) tape.

Based on the oral arguments today there are clearly four votes for the government. All four of the more left-leaning justices—Breyer, Ginsburg, Sotomayor, and Kagan—strongly suggested that the four words at issue in the case, “established by the state,” should be read in the context of the overall law. That is the government’s position. They also heavily criticized Michael Carvin, the lawyer for the challengers (and their patron, the Competitive Enterprise Institute—among other star clients, Carvin previously represented George W. Bush in the Florida election dispute). Justice Ginsburg also asked about whether the petitioners even had standing to sue.

Assuming (and it seems a safe assumption, especially with Justice Scalia’s acerbic comments to the solicitor general) that Justices Scalia, Thomas, and Alito will again rule for Anything-But-Obamacare, that leaves Chief Justice Roberts and Justice Kennedy.

Justice Kennedy made three distinct points that suggest he is leaning in the direction of the government.

First, he joined the liberal justices in expressing concern that the Affordable Care Act, as a whole, could not survive if the phrase in question were read the way petitioners were suggesting. Given that, how could Congress have possibly intended it? Laws are meant to work, not to self-destruct.

Second, Justice Kennedy expressed concern that the insurance system in states without state-established exchanges could be destroyed in the court ruled for the challengers. This, too, has long been a position of Obamacare’s defenders.

Third, Justice Kennedy also posed a novel (and to many observers, unexpected) constitutional question: If federal tax credits were only available to people living in states that did established their own insurance exchanges, Kennedy said, the federal government would effectively be coercing states to do so, in violation of the Tenth Amendment. In other words, if the challengers are right, the ACA itself could be unconstitutional.

Here’s where things get interesting—and not (yet) picked up by most bloggers covering the oral argument. One of the classical canons of judicial interpretation is called the Canon of Constitutional Avoidance. It holds that if a statute is susceptible to more than one reasonable construction, courts should choose an interpretation that avoids raising constitutional problems.

So Justice Kennedy saying that the challengers’ interpretation would render the ACA unconstitutional is another way of saying their interpretation is wrong.

Those three lines of questioning—but especially the third—suggest that Justice Kennedy would be vote number five in favor of reading the phrase “established by the state” in the context of the overall ACA, thus preserving Obamacare.

Now, insert all the relevant disclaimers here. Often, justices make arguments in oral arguments just to try them out—not because they believe them. Sometimes, they want the lawyers to do the best they can to refute them, precisely because the justice wants to refute them in a subsequent opinion. It is foolhardy to infer what a justice thinks from how he or she behaves at oral argument. Which, arguably, is what I’ve just done here.

We know much less about Chief Justice Roberts’ perspective on the case, and his tea leaves are even less legible. On the one hand, he came under withering fire from conservatives for upholding Obamacare in 2012, and pressure to atone for his sins. On the other hand, many legal observers have opined that the challengers’ case is so weak, ruling for them could undermine the court’s legitimacy.

At oral argument, the Chief was quieter than Justice Kennedy. He barely questioned Michael Carvin (a point for challengers?), and dismissed concerns about standing. Theoretically, he might side with an ostensibly literalist reading of “established by the state,” and to more general conservative views on the size and scope of government.

On the other hand, if Justice Kennedy is vote number five, Chief Justice Roberts could easily be vote number six. He could take advantage of the 6-3 split to again write the opinion of the court himself, as is the prerogative of the chief justice, since his would not be the deciding vote. In many ways, Justice Kennedy voting with the government would be a gift to the Chief Justice.

And let’s remember that this particular legal theory is a weak one, hatched in conservative think-tanks. As Justice Breyer pointed out at oral argument, it would “put an elephant in a mousehole”—deciding the validity of an 828-page bill based on four words in a single provision of it. If Chief Justice Roberts is as concerned with the Court’s legitimacy as he appears to be, hanging a politically explosive action on such a slender reed is not a good way to preserve it.

In sum, based on the Chief Justice’s relative silence at oral argument, predicting his view is still a matter of guesswork. But Justice Kennedy, who before oral argument had been seen as a clear “no” vote, now seems to be more sympathetic to Obamacare—and more antagonistic to its challengers.

Stay tuned.