Abstract The ECOWAS case – Case C–91/05, Commission v. Council (''ECOWAS'' or ''Small Arms and Light Weapons''), Grand Chamber Judgment of 20 May 2008 – provided the first opportunity for the Court of Justice to speak out on a legal base conflict between the first (EC) and second (CFSP) pillars, and to shed some light on the distribution of competence between the EC and the EU. Although the Court at first sight opted for a clear preservation of the acquis communautaire, the judgment has implications for the distribution of external competences, both between the pillars and in relation to the Member States. In that, the ECOWAS pronouncement is a milestone in the Court of Justice's jurisprudence on the EU external competence and legal basis, on the functioning of the EU system of external relations and, more generally, on the present and future constitutional architecture of the Union.