On March 23, 2010, the day that President Obama signed the Affordable Care Act into law, fourteen state attorneys general filed suit against the law’s requirement that most Americans purchase health insurance, on the ground that it was unconstitutional. It was hard to find a law professor in the country who took them seriously. “The argument about constitutionality is, if not frivolous, close to it,” Sanford Levinson, a University of Texas law-school professor, told the McClatchy newspapers. Erwin Chemerinsky, the dean of the law school at the University of California at Irvine, told the Times, “There is no case law, post 1937, that would support an individual’s right not to buy health care if the government wants to mandate it.” Orin Kerr, a George Washington University professor who had clerked for Justice Anthony Kennedy, said, “There is a less than one-per-cent chance that the courts will invalidate the individual mandate.” Today, as the Supreme Court prepares to hand down its decision on the law, Kerr puts the chance that it will overturn the mandate—almost certainly on a party-line vote—at closer to “fifty-fifty.” The Republicans have made the individual mandate the element most likely to undo the President’s health-care law. The irony is that the Democrats adopted it in the first place because they thought that it would help them secure conservative support. It had, after all, been at the heart of Republican health-care reforms for two decades.