Major portions of the Civil Rights Act pushed up against what then seemed to be the outer limits of federal power to legislate under the Commerce Clause, and regulated matters traditionally left to the states. The same is true of many other federal statutes that protect the rights of minority groups. Such statutes might have once been thought to be beyond Congress' power. By the 1960s, however, the court's Commerce Clause jurisprudence had evolved to the point where what might once have been unconstitutional became merely controversial, and now is often accepted without question.

Today we take it for granted, for instance, that Congress can pass a statute prohibiting landlords from discriminating against tenants based on race, religion and many other categories. These are precisely the kinds of innovative extensions of Congress' interstate-commerce power that at least four justices suggested were of questionable validity in the ACA opinions.

To be sure, Roberts was careful in his opinion to cite, with approval, the court's nearly 50-year-old decisions that upheld the constitutionality of the 1964 law. But it does not stretch the imagination to envision five members of the court ruling -- in the not-too-distant future -- that a further extension of federal civil rights protections is invalid as an exercise of Commerce Clause power.

Of more immediate concern is the aspect of Roberts' opinion that has been celebrated: his judicial craft. The chief justice avoided a ruling that would have placed the Supreme Court at the center of a political firestorm in an election year. If the ruling had been different, it would have handed President Obama's re-election campaign a potent issue with which to rally its core supporters.

This action surprised many observers, because the Roberts court has not shied away from controversy. As has been well-documented, the court's conservative majority has reached to decide issues not presented for decision, revised well-settled precedents (pdf) and otherwise discarded the norms of judicial restraint (pdf) in service of the results it wants to reach.

More controversial cases await in the near future. Sitting on the court's present docket is a case challenging the University of Texas' use of race in its admissions process, giving the court an opportunity to overturn or modify its own relatively recent precedent upholding race-conscious university admissions.

In addition, the justices have sent clear signals that they may rule, in the near future, that a core provision of the Voting Rights Act is unconstitutional. Justice Thomas, never reticent about such things, is already on record with his opinion (pdf) that it is. Roberts' deft avoidance of political controversy in his Affordable Care Act decision makes it even more likely that he may feel freer to enter into controversial territory in revising apparently settled areas of civil rights law.

But those same considerations of politics give those who favor traditional civil rights approaches a strategy of their own. Recent work by both legal scholars and political scientists has established something that racial minorities have known for a long time: that the Supreme Court is influenced by the larger court of public opinion.

If one interpretation of the ACA decision is that the court hesitated before inserting itself into a national political dispute, then one response to the prospect that the justices may alter settled civil rights law is to organize politically, to make it clear that such change will once again place the court in the middle of a firestorm. The four justices who signed the conservative dissent may be unmoved by such considerations, but a statesmanlike chief justice just might be.

Kenneth W. Mack is a professor of law at Harvard Law School and the author of Representing the Race: The Creation of the Civil Rights Lawyer.

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