Rhetoric often claims that the European Union (EU), in issues related to Justice and Home Affairs, has to be united in its diversity. As such, the asylum and judicial systems of the Member States are initially perceived as equally good. By applying the cosmopolitan theory on two fields of interstate cooperation, asylum and judicial cooperation in criminal matters, the article explores how cosmopolitan the EU is in these fields, with a specific focus on material detention conditions. For cosmopolitanism to work, it has to be grounded in commonly shared norms, which enable the EU to regulate its dealings with the otherness of the Member States. The crucial role of the European Court of Human Rights and the Court of Justice of the European Uni...