In December 2018, the Global Compact for Migration was first adopted at the Marrakesh intergovernmental conference to be later endorsed as an UN General Assembly Resolution in New York. From an EU perspective, what started out as a common project to manage migration globally, not to say externally, became a fiasco for the unity of EU representation on the international scene. Unlike the negotiations of international agreements which are framed by the procedure set out in Article 218 TFEU, the negotiations of international soft law do not benefit from a clear legal framework. The Court of Justice has given some indications on the procedural and institutional aspects relevant for the negotiations of international soft law instruments in the Council v. Commission (C-660/13) case but many uncertainties remain. The purpose of this article is to draw lessons from the negotiation process of the Global Compact for the unity of EU representation.