The CJEU’s decision in the Antarctic Marine Protected Areas (MPAs) case offered an opportunity to explore the area where EU Law and the Antarctic Treaty System overlap: in the forum of the CAMLR Commission. From the point of view of EU Law, CCAMLR is a so-called ‘mixed agreement’, meaning that its scope includes areas where both the European Union and its Member States are competent. This article explains how the Court resolved the question of the joint representation of a common standpoint in a forum where the Union has no autonomous position, and then goes on to explore the significance that the decision could have for the Antarctic Treaty System.