In the last seven years, close to twenty thousand people have died trying to reach Europe by crossing the Mediterranean Sea. Rescue missions by private actors and NGOs have increased because both national measures and measures by the EU’s border control agency, Frontex, are often deemed insufficient. However, such independent rescue missions face increasing persecution from national governments, Italy being one example. This raises the question of how potential migrants and dissenting citizens should act towards the EU border regime. In (...) contrast to the literature, which mainly addresses migration on the basis of justice requirements, this article focuses on the legitimate authority of the EU’s border regime. Focusing on the legitimacy criteria for states’ claims to regulate migration opens a fruitful normative perspective, given the pervasive disagreement over the content of justice in migration. What reasons for compliance and non-interference does legitimacy supply for potential immigrants and dissenting citizens? And what legitimacy standard may be appropriate for the power that individual states claim over potential immigrants? We argue that, even assuming a minimal legitimacy standard for the state-migrant relationship, the structure of the EU’s border regime exhibits unique features, which cause it to stand in tension with such a standard. By coordinating its Member States’ border regimes, especially through Frontex, the EU claims and exercises power over potential immigrants. However, the asymmetrical delegation of state powers to the EU means that the power involved in regulating European borders is, in core respects, unaccountable. This unaccountability, we argue, is significant for the legitimacy of the EU’s border regime. This article sheds new light on the morality of unauthorised rescue missions by assessing the permissibility of resistance to the EU’s border regime. (shrink)