Since Robert Bork, Edwin Meese, Antonin Scalia and their lieutenants founded modern conservative jurisprudence 30 years ago, its core watchword has remained invariant: abhorrence for "activist" judges who "legislate from the bench." To showcase their hostility to activism on the right as well as the left, court-focused conservatives have repeatedly denounced the 1905 U.S. Supreme Court decision Lochner v. New York. Lochner launched and has come to symbolize the notoriously anti-regulatory activism of the first third of the 20th century; the case held that maximum-hours regulation violated employers’ and employees’ "freedom of contract," a "right" that the five-justice majority divined in the Fifth and 14th amendments’ ban on deprivation of liberty without due process of law. Bork called the ruling an "abomination." Meese agreed that the "activist Court of the Lochner era was as illegitimate as the Warren Court." More recently, Chief Justice John Roberts Jr., at his 2005 confirmation hearing, said, "Reading that opinion, it’s quite clear that they’re not interpreting the law, they’re making the law."

That was then. But maybe not now. Within the next year or two, we’ll find out. By then, the Supreme Court should have decided one or more of the pending challenges to the "minimum coverage provision" or "individual mandate" in the new health reform law, which requires most Americans who can afford it to carry health insurance. Roberts and his four fellow Republican appointees cannot strike down the mandate without exhuming Lochner and the doctrinal apparatus deployed a century ago to abort the modern American regulatory state.

Some health reform challengers openly seek such a radical denouement. Virginia Attorney General Kenneth Cuccinelli, a Tea Party favorite who filed his complaint the moment President Obama signed the new law, touts the lawsuits as aimed at shrinking government across the board. The judge handling the case, Henry E. Hudson of the Eastern District of Virginia in Richmond, evinces no reservations about embracing this rollback agenda. When, on Dec. 13, he granted Cuccinelli’s motion to declare the individual mandate invalid, Hudson relied in part on a 1922 ruling, universally considered defunct for three-quarters of a century, that Congress lacked power to ban or discourage the use of child labor in manufacturing.

More judicious conservatives, while baring animus for the health reform law itself, eschew any such broad-scale counterrevolutionary design. These more circumspect legal conservatives appear to be searching for a way to overturn the mandate via surgical reasoning that, in the words of Georgetown University libertarian professor Randy Barnett, leaves intact "existing doctrine by which the Supreme Court construes the Commerce and Necessary and Proper Clauses."

Federal District Judge Roger Vinson, a Reagan appointee who is handling the challenge filed in the Northern District of Florida by 20 Republican state attorneys general and governors, appears to be in this camp. In a preliminary decision on Oct. 14, Vinson fervently endorsed the opponents’ legal theory that mandatory insurance amounts to regulating "inactivity," which, they allege, is ­categorically beyond the reach of the commerce clause.

But he shunned Lochner-era precedents or doctrines. In particular, he dismissed Republican officials’ claim that the mandate violates individuals’ Fifth Amendment due process rights. He brushed aside, as "long since discarded," Lochner and kindred decisions that interpreted "the Due Process Clause…to reach economic rights and liberties." Since the New Deal, he noted, due process-based claims cannot stand against economic laws that are "rationally related to a legitimate end." Here, he stated: "Congress made factual findings…that the individual mandate was ‘essential’ to the insurance market reforms contained in the statute." There would appear to be a stark contradiction here, unnoticed by Vinson. In endorsing the legal theory behind the Republican officials’ commerce clause attack, he neglected to mention, much less reconcile, his flat statement one page earlier when assessing their due process claim, that Congress had established a "rational basis justifying the individual mandate" as a matter of law.

This is not a quibble. The right asserted by the state officials challenging the mandate is, as Vinson noted in his Oct. 14 opinion, a "liberty interest." In oral argument on summary judgment on Dec. 16, he continued in the same vein, suggesting that "[t]here’s lots of ways to provide health insurance without imposing on individual liberties and freedom of choice." Substantive due process is the established venue for gauging whether a claimed liberty interest is "fundamental" enough to trump rational legislation implementing an enumerated power. And for good reason. When the state officials’ objection to the health reform mandate is subjected to the rigorous scrutiny prescribed by post-New Deal precedent, its sheen as a liberty interest vanishes. To be sure, the Supreme Court has held that an individual’s right to refuse medical treatment is "fundamental," and can prevail over an otherwise valid federal requirement. But that does not exempt individuals from paying Medicare taxes, thereby contributing to the Medicare insurance pool. If the right to avoid payment for treatment were constitutionally "fundamental," then Medicare taxation would be vulnerable to due process attack, as would state mandatory insurance requirements like those enacted by Massachusetts in 2006.

Indeed, refusing to carry health insurance may not constitute a genuine liberty interest at all. Treating uninsured patients, as most hospitals are required by federal statute to do, shifts more than $40 billion in costs annually to providers and insured consumers, to the tune of more than $1,000 per family in increased premiums. As former Massachusetts Gov. Mitt Romney noted when signing the Massachusetts individual mandate: "A free ride on the government is not libertarian."

Opponents’ challenge to the federal provision stands or falls by the same logic, whether cast as a "fundamental" incident of due process or as an implicit carve-out from Congress’ authority to regulate interstate commerce. Slipping the inquiry from one constitutional shell to another should fool no one. If conservative jurists invalidate this linchpin of the most important domestic legislation in perhaps half a century, they will restore Lochner — letter, spirit, the whole nine yards.

Simon Lazarus is public policy counsel at the National Senior Citizens Law Center in Washington.