Democrats didn’t see it coming: Before the passage of the Affordable Care Act in 2010, neither congressional leaders nor the White House anticipated that one specific provision—the mandate requiring individuals to maintain a minimum level of health insurance—would spark such a ferocious political and legal backlash. Yet, nearly two years later, controversy surrounding the mandate dominates the national conversation about health care reform. The constitutionality of the mandate is the central issue in the legal challenge to the Affordable Care Act, which the Supreme Court will take up this March. And overturning the mandate has provided a rallying cry for Republican opposition to President Obama.

The story of the individual mandate is replete with ironies. Obama spent much of the 2008 primary season denouncing the mandate, which Hillary Clinton supported. At the time, Mitt Romney was strongly identified with the idea, which had been central to the reforms he introduced as governor of Massachusetts. Four years later, Romney may be the nominee of a party that abhors the mandate, while Obama now defends it. Yet perhaps the greatest irony has to do with the mandate’s policy merits. Many liberals assume that universal health care requires an individual mandate; but there are arguably better alternatives. In fact, as the law stands, the mandate may simply not work because it lacks adequate means of enforcement.

For Democrats, then, saving the Affordable Care Act—legally, politically, and practically—could very well mean getting rid of the mandate. And it is not too soon to begin thinking through how—if the opportunity arises after next November—they might accomplish this.

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The individual mandate was not always embraced by liberals. Indeed, the idea originated on the right. In 1989, Stuart Butler of the Heritage Foundation proposed an individual mandate as part of a plan for “assuring affordable health care for all Americans”; two years later...