Addicted to Exclusivity in EU External Action: Another Chapter in Constitutionalising the Unity of EU Representation in International Fora. Case C-271/23 [GC], European Commission v Hungary (Reclassification of Cannabis)

The unity of European Union (EU) external action has been repeatedly tested in recent years, with Hungary frequently obstructing common EU positions in international fora. This case note examines the January 2026 Grand Chamber judgment of the Court of Justice of the EU (CJEU) in Commission v Hungary (Reclassification of cannabis) (Case C-271/23), in which the CJEU addressed one such disruption within a multilateral setting – the United Nations (UN) Commission on Narcotic Drugs. Arising from an Article 258 TFEU infringement action, the case turned on whether an EU Member State may ‘break free’ and vote against a common EU position on the ground that it considers that position unlawful. The European Commission contended that Hungary’s departure from Council Decision (EU) 2021/3 – fixing the Union's position on the scheduling of cannabis and related substances under two UN drug-control conventions – infringed both the EU’s exclusive external competence (Article 3(2) TFEU) and the duty of sincere cooperation (Article 4(3) TEU). The CJEU agreed on every count. Through an expansive construction of EU exclusive external competence and a robust, stand-alone application of the constitutional principle of sincere cooperation, the CJEU reinforced the unity of EU external action while sharply curtailing Member States’ room to act unilaterally in international fora – even in those the EU cannot formally join. This Grand Chamber ruling promises greater discipline and consistency in EU external action; yet risks chilling dissent on sensitive matters. Ultimately, it stands as a significant brick in the increasingly constitutional edifice of EU external relations law.