Since Opinion 2/13, the ECJ has gradually clarified that its role in the field of CFSP is less limited than a cursory reading of the Treaties may suggest. This article aims to take stock of this evolving case law and discuss the remaining uncertainties and criticisms regarding the Court’s approach. After a brief introduction to the ambiguous position of the CFSP in the EU legal order, specific attention is devoted to the “gap-filling” role of the ECJ’s case law in relation to CFSP matters. It is argued that the Court has developed a consistent line of case law, based on the horizontal application of general constitutional principles and mechanisms. The question remains how much further this “gap-filling role” can be stretched in light of the principles of institutional balance and conferral. The article discusses to what extent the specific features of EU law as regards judicial review in CFSP matters may still be regarded as an obstacle for EU accession to the ECHR.