Last week Damon Root wondered whether there are five votes on the Supreme Court to overturn the Patient Protection and Affordable Care Act's requirement that every American obtain government-approved health insurance. Clarence Thomas and Antonin Scalia are the justices most likely to vote against the mandate, since they have long records of worrying about the ill-defined limits of Congress's power to "regulate commerce...among the several states." Assuming that John Roberts and Samuel Alito are also on board (not necessarily a safe assumption, as Damon noted), Anthony Kennedy could provide the swing vote, as he often does, which makes his concurring opinion in U.S. v. Lopez newly interesting. That is the 1995 decision in which the Supreme Court overturned a federal ban on gun possession in or near schools, concluding that accepting the arguments in favor of the law would require it "pile inference upon inference in a manner that would bid fair to convert congressional authority under the Commerce Clause to a general police power of the sort retained by the States." It was the first time in 60 years that the Supreme Court had overturned a federal law on Commerce Clause grounds.

Kennedy's lukewarm concurrence in Lopez is not exactly encouraging. He wrote a separate opinion (joined by Sandra Day O'Connor) to highlight his reluctance to impose limits on Congress's power:

The history of the judicial struggle to interpret the Commerce Clause during the transition from the economic system the Founders knew to the single, national market still emergent in our own era counsels great restraint before the Court determines that the Clause is insufficient to support an exercise of the national power. That history gives me some pause about today's decision.

Although Kennedy concluded that federalist principles required that states be free to determine their own policies in "an area of traditional state concern," his summary of the Court's jurisprudence clearly favored an expansive reading of the Commerce Clause, treating a narrower (and more historically grounded) understanding focused on the elimination of interstate trade barriers as impractical and economically obsolete. In contrast with the majority opinion's emphatic concern about erasing the "distinction between what is truly national and what is truly local," Kennedy seemed more worried about being insufficiently deferential to Congress, venturing to say only that "our cases do not teach that we have no role at all in determining the meaning of the Commerce Clause."

Kennedy did hint at the dangers posed by the "substantial effects" doctrine, under which Congress may regulate purely intrastate activities based on tenuous or hypothetical connections to interstate commerce. "In a sense," he wrote, "any conduct in this interdependent world of ours has an ultimate commercial origin or consequence, but we have not yet said the commerce power may reach so far." (In his concurring opinion, Clarence Thomas went much further, warning that "our case law has drifted far from the original understanding of the Commerce Clause" and calling for reconsideration of the "substantial effects" doctrine, lest it provide a "blank check" for congressional action.) Despite his reservations about defining the boundaries of the Commerce Clause, Kennedy joined the majority opinion in U.S. v. Morrison, the 2000 case in which the Court overturned a federal civil remedy for victims of gender-motivated violence. This time he did not feel a need to file a separate opinion.

One reason Kennedy might be comfortable voting to overturn the health insurance mandate is that it goes farther than any purported regulation of interstate commerce the Court has ever approved by targeting the passive inactivity of failing to buy something that Congress thinks everyone should have. Since every law that has been upheld under the Commerce Clause has involved some sort of activity (even if it was limited to growing plants for personal use), the Court need not reconsider its precedents to reject the insurance requirement. As I argue in my column tomorrow, that is both the main advantage and the main disadvantage of the activity/inactivity distinction embraced by U.S. District Judge Roger Vinson last week and U.S. District Judge Henry Hudson in December.