In 2016, the European Parliament and the Council adopted a legislative act creating and regulating a new European Border and Coast Guard Agency. Its Article 19 states that – should a Member State’s failure to control its own borders jeopardize the collective effort to monitor the external borders of the Schengen Area – the new Agency could take over the management of border control operations in that Member-State. This transfer of power begs a crucial question regarding EU’s conflict of sovereignties. First, this article identifies three paradigmatic conceptions of sovereignty (traditional, post-sovereignist, and post-traditional), and, second, it applies them to our case study to assess which conception provides the best explanatory model. We eventually argue that the post-traditional perspective proves the fittest to capture the current integration of the EU’s external border management, best described as an institutional bricolage (by contrast with a grand architectonic design).