ABSTRACT – The Agreement on the conservation and sustainable use of marine biodiversity in areas beyond national jurisdiction (BBNJ Agreement), which entered into force on January 17, 2026, is the first legally binding instrument for the protection of biodiversity on the high seas. The proposed directive COM (2025) 173, aimed at transposing its obligations, raises two issues of systemic importance regarding the allocation of competences. The first concerns the correct identification of the legal basis for the act: in light of the “center of gravity” criterion developed by the Court of Justice in the AMP Antarctique judgment (joined cases C-626/15 and C-659/16), it is argued that the choice of Article 192(1) TFEU is consistent with the teleology of the Agreement, whose primary purpose is the ecosystem-oriented protection of marine biodiversity. The second issue concerns the division of competences between the Union and the Member States in mixed agreements and the consequent operation of the regulatory pre-emption mechanism. In this regard, the Italian Parliament’s reasoned opinions are critically examined, noting that their excessively restrictive interpretation of the principle of subsidiarity appears difficult to reconcile with the functional logic of the Union’s external action regarding international ocean governance.
