This paper argues that libertarianism—and only libertarianism—can vindicate immigration's status as a human right whose protection is morally required in nearly all circumstances. Competing political theories such as liberal egalitarianism fail to rule out significant immigration restrictions in a range of realistic conditions. We begin by outlining the core tenets of libertarianism and their implications for immigration policy. Next, we explain why arguments that appeal to alternative principles are unable to provide robust justification for open borders. We conclude by considering (...) whether our argument vindicates libertarianism or undermines open borders. (shrink)