As the COVID-19 pandemic continues to evolve, taking its toll on people’s lives around the world, vaccine passports remain a contentious topic of debate in most liberal democracies. While a small literature on vaccine passports has sprung up over the past few years that considers their ethical pros and cons, in this paper we focus on the question of when vaccine passports are politically legitimate. Specifically, we put forward a ‘public reason ethics framework’ for resolving ethical disputes and use the (...) case of vaccine passports to demonstrate how it works. The framework walks users through a structured analysis of a vaccine passport proposal to determine whether the proposal can be publicly justified and is therefore legitimate. Use of this framework may also help policymakers to design more effective vaccine passports, by incorporating structured input from the public, and thereby better taking the public’s interests and values into account. In short, a public reason ethics framework is meant to encourage better, more legitimate decision-making, resulting in policies that are ethically justifiable, legitimate and effective. (shrink)