In apparent panic at the tenor of the Supreme Court argument over the constitutionality of the Affordable Care Act (aka ObamaCare), liberal law professors have exploded with anticipatory denunciations of the court's conservative justices—claiming that it would be "hypocritical" and "partisan" of them to invalidate legislation passed by Congress when they generally oppose "judicial activism."

It appears the professors' idea of sound jurisprudence is that their favored justices are free to invalidate statutes that offend their sensibilities whether or not the words of the Constitution have anything to say on the matter, as in the case of same-sex marriage or partial-birth abortion, and even if the Constitution seems to endorse it, as in capital punishment. But if conservative justices have the temerity to enforce actual limits on government power stated in Article I, Section 8—over liberal dissents—then they are acting as shameless partisans.

It seems unlikely this one-sided definition of "activism" will persuade anyone. Judicial review might be aggressive and it might be deferential, but there cannot be one set of rules for liberal justices and another set for conservatives.

If liberal supporters of the health-care law were as confident of the merits of their position as they claim to be, they would offer actual legal arguments, based on text, history, structure and precedent, instead of labeling justices with whom they disagree as hypocrites and partisans.

The health-care case is hard for a reason. As James Madison wrote in The Federalist, No. 37, "marking the proper line of partition between the authority of the general and that of the State governments" is so "arduous" that it will "puzzle the greatest adepts in political science."

As American commerce has grown more national and even global in nature, the line has become only harder to draw. It is not intellectually responsible for defenders of the health-care statute to pretend there is only one clear right answer to the case, and to imply that those who disagree must be blinded by partisanship.

Both sides in the ObamaCare litigation agree, in principle, that a line must be drawn somewhere, and that it must be drawn by the Supreme Court. As the great Chief Justice John Marshall put it, the enumeration of certain powers of Congress "presupposes something not enumerated," and "by this tribunal alone can the decision be made." It is not "judicial activism" for the court to do its duty to draw this line. Unlike some cases that could be named, the court is not thrusting itself into a political controversy where the Constitution has nothing to say.

The states challenging the individual mandate rely on a simple conceptual point: Under its power to regulate "commerce," Congress can regulate only transactions taking place in the economy; it has no power to regulate nonactivity—to regulate persons not engaged in commerce by requiring them to buy products or services they would not otherwise purchase, in this case health insurance.

That may be a correct reading of the Constitution, or not, but it must be taken seriously. There is no precedent either way, because Congress has never passed a law like this before.

The oral arguments made before the Supreme Court in March revealed that the defenders of the health-care mandate are unable to identify any line between what they say Congress can do and what it cannot. The solicitor general offered various reasons why health care is unique, but none of them are grounded in any principle based in constitutional text, history or theory. That does not mean ObamaCare is doomed. But it does mean that, if the court wishes to uphold the statue, the justices will have to come up with their own rationale.

The drafters and defenders of the health-care law have only themselves to blame for this mess. With a filibuster-proof Senate and total domination of the House, they did not trouble to build the consensus necessary for transformative legislation of this scope.

More importantly, they did not take seriously their obligation to legislate within the limits set by the Constitution. Indeed, when a reporter asked in October 2009 what the constitutional basis was for the statute, then-House Speaker Nancy Pelosi dismissively responded, "Are you serious?"

Either the drafters of the legislation should have stayed within the generous bounds of authority established by prior precedent, or the administration's lawyers needed to offer a legal defense for going beyond those precedents that does not do violence to fundamental structural features of our Constitution. They could hardly expect the independent judiciary to write Congress a blank check of plenary regulatory authority, without discernible limit.

Mr. McConnell, a former federal judge, is a professor of law and director of the Constitutional Law Center at Stanford Law School, and a senior fellow at the Hoover Institution.

overlay image