Constitutional democracies unilaterally enact the laws that regulate immigration to their territories. When are would-be migrants to a constitutional democracy morally justified in breaching such laws? Receiving states also typically enact laws that require their existing citizens to participate in the implementation of immigration restrictions. When are the individual citizens of a constitutional democracy morally justified in breaching such laws? In this article, I take up these questions concerning the justifiability of noncompliance with immigration law, focusing on the case of nonviolent – or mere – noncompliance. Dissenting from Javier Hidalgo’s view, I argue that the injustice of an immigration law is insufficient to make mere noncompliance justified. Instead, I contend that only if an immigration law lacks legitimate authority are individuals justified in breaching it, since the subjects of an institution with legitimate authority are under a content-independent moral duty to comply with its rules. I further argue that a constitutional democracy’s regimes of law regulating immigration and requiring its citizens’ participation in implementing these regulations have legitimate authority. Nevertheless, when a particular immigration law is egregiously unjust, its legitimacy is defeated.