Used appropriately, reliance on science distinguishes public health from policymaking driven more by theory and opinion and enhances trust in public health interventions. Evidence-based vaccine policymaking aims to control communicable disease by urging decision makers to base policies on the best available evidence rather than politics or personal views. The results of this approach, such as smallpox eradication, have been dramatic. Historically, mandatory childhood vaccination has been perhaps the most successful evidence-based tool in combating many epidemics. Philosophically, vaccination mandates correspond (...) to the legal system’s dual role in codifying what society deems undesirable behavior and declaring beneficial social norms and values consistent with understandings of the social contract. Despite their effectiveness and philosophical grounding, vaccination mandates present serious legal and ethical questions. Public health policymakers have a continuing responsibility to rely on evidence not only as a basis for generating policy, but also for evaluating and improving elements of its legal design. (shrink)