Note: This piece has been revised to reflect that the Affordable Care Act’s religious exemption is narrowly worded to apply only to a religion that “is conscientiously opposed to acceptance of the benefits of any private or public insurance which makes payments in the event of death, disability, old-age, or retirement or…medical care.”

The oral arguments on the health insurance mandate did not go especially well for the government, in part because it mistakenly chose to accept the opponents’ erroneous framing that it would be unprecedented for Congress to require individuals to purchase something. But even though it needlessly gave itself an uphill burden by accepting this mistaken framing, the comments of Chief Justice John Roberts Jr. and Justice Elena Kagan suggested a compromise that might still save the health insurance mandate.

Rather than forthrightly arguing that in fact a lot of precedent indicated Congress could require individuals to purchase something, the government chose to rely solely on the alternative argument that the uninsured were as a class active in the health care market. The government had some strong evidence that most of the uninsured received health care within a year and almost all did within five years, and that when they did, two-thirds of the cost were borne by others when the uninsured were unable to pay for it. Thus, the government argued, those choosing to be uninsured were nonetheless, as a class, predictively active in health care markets in ways that cost the rest of us money.

The four liberal justices clearly seemed to buy this argument. Chief Justice Roberts and Justice Anthony Kennedy seemed somewhat sympathetic as well, notwithstanding their general skepticism about whether Congress could impose a duty to engage in commerce. The challengers to the mandate responded that each year many of the uninsured did not end up getting health care and an even smaller percentage ended up being unable to pay for it. Chief Justice Robert’s response was “Yet we don’t know who they are.”

Here is where Justice Elena Kagan’s comments suggested an intriguing possible compromise. She followed up Chief Justice Robert’s remarks by noting that the case “might be different if you were…presenting a class of people whom you could say clearly would not be in the health care market.” (For example, she had earlier observed that the case would be different if the opponents were representing a “a class of Christian Scientists” who were religiously opposed to accepting medical treatment and thus could convincingly show that they would not be active in the health care market.) The problem here, as she put it, was that “you’re raising a facial challenge and we can’t really know which, which of the many, many, people that this law addresses in fact will not participate in the health care market and in fact will not impose costs on all the rest of us.”

This suggests a possible compromise that a majority of the Court might unite around. Namely, the Court could hold that: (1) this facial challenge to the application of the mandate to everyone fails because the challengers could not show which of the uninsured would not be active in health care markets, but (2) the mandate might be unconstitutional as applied to a more narrow class of persons who could prove they would never purchase health care.

This compromise could provide Justice Kagan’s hypothetical class of Christian Scientists with a constitutional exemption from the mandate that they would otherwise lack.  (Although the statute has a religious exemption, it is limited to religions that oppose any form of social insurance, including retirement benefits, and thus does not cover religions that solely object to medical treatment.)  More broadly, this compromise could give the Court a way of sustaining the mandate while still finding a constitutional limit that could apply to any other group that could definitely prove they would not buy health care.  This might include, for example, a group of libertarians willing to sign a “dying will” that commits to waive the right to be treated even in the case of emergency.

This sort of compromise could give both sides what they want most. It would give one side the practical right to require insurance for the vast bulk of people who cannot assure they will not end up getting health care. But it would give the other side affirmation that Congress cannot obligate persons to enter into a market that they can show they would otherwise avoid.

Einer Elhauge is Petrie Professor of Law at Harvard Law School and the founding director of the Petrie-Flom Center in Health Law Policy. He joined an amicus brief arguing that the mandate is constitutional, and his investment portfolio includes some health care investments that might be affected financially by a ruling on the mandate.