When Obamacare first passed, then-House Speaker Nancy Pelosi incredulously responded to a query about whether the law was constitutional with: "Are you serious?" After Tuesday's oral argument, she might want to revise and extend her remarks; a 5-4 vote seems almost certain based on the tone of the individual justices' questions.

The law's proponents had hoped that Justice Antonin Scalia, author of the Raich opinion upholding a federal marijuana prosecution in the face of a state ballot initiative to the contrary, might provide a 6th vote for them. But Justices Scalia, John G. Roberts Jr., and Samuel Alito were highly dubious of the government's position.

It is assumed that Justice Clarence Thomas, who almost never asks questions during oral argument and has historically voted to limit government power, will vote the individual mandate is improper. The "liberal" justices, Elena Kagan, Sonia Sotomayor, Stephen G. Breyer and Ruth Bader Ginsburg all seemed to be in favor of the law.

Not surprisingly, that leaves Justice Anthony M. Kennedy as the swing vote. He asked some interesting questions. He asked the Solicitor General: "Assume for the moment that this is unprecedented, this is a step beyond what our cases have allowed, the affirmative duty to act to go into commerce. If that is so, do you not have a heavy burden of justification? I understand that we must presume laws are constitutional, but, even so, when you are changing the relation of the individual to the government in this, what we can stipulate is, I think, a unique way, do you not have a heavy burden of justification to show authorization under the Constitution?"

He also recognized that this case is breaking ground in that Congress is trying to do something new — make people enter into a contract: "But the reason, the reason this is concerning, is because it requires the individual to do an affirmative act. In the law of torts our tradition, our law, has been that you don't have the duty to rescue someone if that person is in danger. The blind man is walking in front of a car and you do not have a duty to stop him absent some relation between you. And there is some severe moral criticisms of that rule, but that's generally the rule. And here the government is saying that the Federal Government has a duty to tell the individual citizen that it must act, and that is different from what we have in previous cases and that changes the relationship of the Federal Government to the individual in the very fundamental way."

On the other hand, he seemed sympathetic when discussing the government's contention that the health care market or perhaps the health insurance market is unique: "But I think it is true that if most questions in life are matters of degree, in the insurance and health care world, both markets — stipulate two markets — the young person who is uninsured is uniquely proximately very close to affecting the rates of insurance and the costs of providing medical care in a way that is not true in other industries. That's my concern in the case."

And when Paul Clement, a former Solicitor General who was appearing for the 26 states challenging the law, attempted to claim that the uninsured were not market participants and therefore not engaged in "commerce," which is a requirement before Congress can legislate, Justice Kennedy asked: "But they [meaning those who choose not to buy insurance] are in the market in the sense that they are creating a risk that the market must account for."

The manner in which Justice Kennedy resolves his questions will likely tell us whether the law is constitutional or not.

Patrick Wright is senior legal analyst at the Mackinac Center for Public Policy, where he directs the Mackinac Center Legal Foundation