Despite an increased level of legalization of JHA, academic literature has paid little attention to the role of law in this field. It is the objective of this article to assess the EU's attempt to reconcile its current practices of extraterritorial border control coordinated by Frontex in the Mediterranean with international human rights law, notably the principle of non‐refoulement. By drawing on insights on both rationalist and constructivist accounts, we argue that international human rights principles such as non‐refoulement are usually broad enough for everyone to identify and agree with and to provide state actors sufficient leeway to interpret the rules according to their interest. However, thanks to the activities of numerous inter‐, supra‐, and transnational actors offering various and competing legal interpretations, EU member states feel compelled to react by triggering several rounds of rule‐specification that have the power to clarify pertinent law and strengthen fundamental rights standards.