Republicans are screaming that Obamacare’s mandates are a “stunning assault on liberty,” as one put it. That’s ironic, since Richard Nixon, Bob Dole, and Bill Frist all embraced the idea.

The new mandate requiring Americans to buy health insurance is “the most egregious, unconstitutional legislation that we can remember,” said South Carolina Republican Attorney General Henry McMaster. He is among more than a dozen state attorneys general who have filed a lawsuit asking the courts to declare the mandate unconstitutional because it is “an unprecedented encroachment” on the rights of both individuals and the states by the federal government. The political scrum that’s erupted over the mandate plan is deeply ironic—given that the idea has been warmly embraced by elements of the right since at least the early 1970s.

Far from the “stunning assault on liberty” decried by Arizona Sen. Jon Kyl, the individual mandate is partially traceable to conservative embrace of an anti-Medicare, pro-free-market health-reform agenda. President Nixon’s Office of Management and Budget Director Caspar Weinberger believed that providing insurance to all Americans was a worthy goal, for instance. At the same time, he opposed reforms that would expand a government-run health-care system. So, as Daily Beast contributor Adam Clymer recounts in his fine biography of Sen. Ted Kennedy, Weinberger proposed a “solution” that would put the burden on employers “by requiring them to insure their workers.” This was an “employer mandate,” and it appealed to Weinberger among others because it ensured that health care in America would remain in the hands of the private sector, not fall under control of Washington.

The bombastic rhetoric characterizing mandates as the end of liberty and the lawsuit filed by the attorneys general have a hypocritical, hyperbolic cast about them.

While Nixon-era efforts to enact universal coverage ultimately faltered, the mandate concept didn't die. Instead, the idea that individuals should be required to buy insurance in the private marketplace gained intellectual momentum and attracted its share of political defenders during debates over Bill Clinton's proposals in the early 1990s.

Conservatives were drawn to individual mandates for two related reasons. First, they would strengthen rather than undermine the private insurance marketplace. Second, they would provide a constructive laissez-faire alternative to the liberal single-payer approach to achieving the goal of national health insurance.

It was conservative because it was a responsible idea friendly to the health-care marketplace—and embraced personal responsibility as a virtue. Author David Frum pointed out in his 1996 essay collection What’s Right: The New Conservative Majority and the Remaking of America that the individual mandate was among three major conservative reform ideas circulating at the time.

• Mark McKinnon: Can This Man Save the GOP?Endorsed by Stuart Butler of the conservative Heritage Foundation and conservative economists such as Milton Friedman and Wharton’s Mark Pauly, individual mandates as an idea were at least partially generated by pro-free-enterprise intellectuals. “Heritage figured that since everyone in the country was getting some form of health coverage anyway, everyone ought to buy it,” explained Frum. “But unlike most liberal schemes, the Heritage plan imposed the obligation to buy insurance, but on individuals rather than employers.”

During the early '90s debate, the individual mandate and Heritage plan generally even came to “[look] like a daring free-market reform.” More than just a dust-gathering think tank idea, the individual mandate won plaudits from some prominent Republican elected leaders. In late 1993, Senate Leader Bob Dole cosponsored legislation with John Chafee that would have required individuals to buy health insurance. More recently, former Massachusetts Gov. Mitt Romney and former Sen. Majority Leader Bill Frist praised individual mandates as conservative and welcome steps toward health reform.

Not all conservatives have been enamored of the idea, of course. Libertarians “disliked ordering people to buy insurance,” said Frum; even Butler walked away from his plan in the end. (Republicans, like Democrats, have had their own disputes over the smartest, most principled approach to reforming health care and achieving universal coverage.)

Still, the bombastic rhetoric characterizing mandates as the end of liberty and the lawsuit filed by the attorneys general have a hypocritical, hyperbolic cast about them. Individual mandates have historically been regarded, at times, as a conservative agenda—one that would deliver on the promise of universal coverage while strengthening the private health-insurance system. It’s no small irony that instead of celebrating the triumph of their market-based approach to reforming health care, some conservatives in 2010 are denouncing the plan as the end of America as we know it.

Matthew Dallek teaches history and politics at the University of California’s Washington Center. He is the author of The Right Moment: Ronald Reagan's First Victory and the Decisive Turning Point in American Politics.