The Supreme Court’s decision upholding Obamacare revealed a vast difference of opinion over the nature and meaning of the Constitution. Not between the left and the right—those disagreements are nothing new and utterly familiar—but among conservatives themselves.

A large majority of conservatives deplored the ruling, arguing that the president’s dreaded health care law remained an unconstitutional usurpation of power. Chief Justice John Roberts was denounced as a traitor to conservatism and the Constitution. But Roberts was not without conservative defenders.

A significant minority on the right, disproportionately including the legal conservatives from whose ranks George W. Bush plucked Roberts in the first place, critiqued the critics. Without exactly agreeing with the ruling, Matthew J. Franck of National Review’s Bench Memos blog asserted, “I am more convinced than ever that Roberts has a fully plausible case that can be defended on principled grounds.” The libertarian lawyer Doug Mataconis went a step further, arguing, “those on the right attacking [Roberts] now are revealing quite clearly that the are motivated not by an honest criticism of the legal reason the Chief Justice used in his opinion, but because all along it’s only been the result, not the law, that matters to them.”

The political journalist Jay Cost opined in the Weekly Standard that Roberts’ limitations on the commerce clause and the Medicaid expansion were “two enormous triumphs in the century-long war over the principle that the Constitution forbids unlimited federal power.” Veteran conservative columnists George Will and Charles Krauthammer concurred. These voices got a major endorsement when Randy Barnett—the libertarian law professor who helped frame legal arguments against Obamacare that wouldn’t have required junking decades of commerce clause precedent—took to the pages of theWashington Post to proclaim the decision a loss on health care but a win for the Constitution.

It’s a debate that goes beyond any particular legal strategy or even the merits of the Affordable Care Act case. Conservatives have long had their own vocabulary to describe their devotion to the Constitution. They purport to be “textualists,” “originalists,” or “strict constructionists” seeking to discover “original intent.” They dislike judges who “legislate from the bench” rather than strictly interpret the law, and their presidential candidates promise to appoint jurists in the mold of Rehnquist, Scalia, Thomas, Alito, and (until recently) Roberts to replace them.

Liberals frequently argue that all these words don’t really mean anything. That isn’t exactly true, but their meaning is less precise than conservatives often suppose—and conservatives themselves disagree about the actual content of these concepts. Consider the concepts of judicial activism and judicial restraint.

Forerunners of the modern American conservative movement had no qualms about using the Supreme Court to invalidate much of FDR’s New Deal economic agenda, much like the legal campaign against Obamacare. But contemporary conservatives cut their teeth on arguments that undemocratic judges were tossing aside duly enacted laws in favor of their own policy preferences. The right wanted to impeach Earl Warren because his Court was overturning state laws and social customs, not because it had made constitutional peace with the New Deal. By the Reagan administration, attorneys committed to this view began to secure judgeships and employment in the Justice Department, articulating a legal case for judicial restraint.

Steven Teles, author of The Rise of the Conservative Legal Movement, described Roberts as “a Reagan Justice Department-era conservative.” In a post at the Washington Monthly, Teles argued:

That era of conservatives were pissed off at the activist judiciary that brought us school busing and other forms of what they took to be social engineering … and an inversion of American federalism. But that generation of conservatives were basically followers of Justice Frankfurter, and they tended to argue that it was 1960s/70s judicial liberalism that they were against, which they claimed was a kind of Lochnerism of the left. That kind of judicial conservatism—which was really Robert Bork’s style of conservatism, and the origin of his version of originalism—is in very stark contrast to legal libertarianism that inspired the case against the ACA.

In contrast with many other strict constitutionalists on the right, Bork—one of the leading lights of the conservative legal movement whose failed Supreme Court nomination was one of the great lost causes of the Reagan era—actually believed the Tenth Amendment was unenforceable. “If he was right,” wrote the columnist Joe Sobran, “then the whole Constitution was in vain from the start.”

Sobran eventually abandoned his constitutionalism and died a “reluctant” philosophical anarchist. But his basic view has been held by many on the right who invoke the Constitution, from Barry Goldwater’s Conscience of a Conservative to the Tea Party today: the founding document created a federal government with a few defined enumerated powers, delegated by the states and the people through the ratification process.

Constitutional conservatives of one stripe might be hesitant to strike down an act of the legislature, searching Roberts-like for some way to read the statue that might comport with the Constitution. But the variety more concerned about restraining the federal government than judicial restraint would look at Article I, Section 8 in conjunction with the Ninth and Tenth Amendments, concluding that something like the Affordable Care Act couldn’t possibly be constitutional whether the individual mandate is a tax or a banana.

Four out of five Republican appointees to the Supreme Court came closer to the latter view than Roberts’ alleged judicial restraint, so perhaps this disconnect is fading. But not all strict constructionists are created equal.

W. James Antle III is associate editor of The American Spectator and a contributing editor of The American Conservative. Follow him on Twitter.