Having undergone an extensive process of political discussion and debate, the ACA (properly the Patient Protection and Affordable Care Act) is now under intensive legal challenge with over 20 different cases from both states and organizations and individuals having been initiated. The challengers argue that the Act lacks a constitutional basis and/or infringes on their constitutional rights. These cases involve a fascinating intersection of legal, political and policy issues and, regardless of the outcome, will have important implications for the future direction of US health care policy. There have now been four decisions of the courts of appeal on the substantive issues involved with the courts involved coming to different conclusions as to the constitutionality of the legislation. This article discusses the issues involved, in particular whether the individual mandate is constitutional under the Commerce Clause of the US Constitution and analyzes how the courts of appeal have addressed this issue in the cases to date. It considers how the case may be addressed by the US Supreme Court.