The Supreme Court’s decision in National Federation of Independent Business v. Sebelius (NFIB) shocked the legal world. Many observers predicted the decision’s central holding: that Congress in the Patient Protection and Affordable Care Act (PPACA) had proper constitutional authority to impose the Act’s “individual mandate,” which requires that all Americans purchase health insurance if they can afford it. Almost everyone expected the Court’s four more liberal Justices to vote to uphold the Act and at least three of the Court’s conservatives to vote to strike most or all of it down. Chief Justice Roberts’s lead opinion, however, produced a cascade of surprises. The conservative Chief Justice joined the Court’s liberals in upholding the individual mandate; he reached that conclusion based on Congress’s taxing power, rather than its powers under the Commerce Clause or the Necessary and Proper Clause; he nonetheless declaimed at length about how those other powers did not support the mandate; and he struck down a key element in the Act’s expansion of Medicaid. Meanwhile, the Court’s four other conservative Justices filed a jointly authored dissent that conspicuously failed to endorse even those aspects of the Chief Justice’s opinion on which all five conservatives agreed, while two of the Court’s liberals—Justices Breyer and Kagan—joined the Chief Justice, without comment, in weakening the Medicaid expansion.