There can be little doubt that the long-awaited judgment of the Court of Justice in the Achmea case delivered on 6 March (Case C-284/16, Slovak Republik v. Achmea BV) gives the last word on the (even longer) debated issue relating to the (in)compatibility of intra-EU investment bilateral investment treaties (BITs) with the EU legal order. In particular, in sharp contrast with the Opinion of AG Wathelet, the Court does not hesitate to state that an arbitration tribunal established under a BIT between two Member States «call[s] into question not only the principle of mutual trust between Member States but also the preservation of the particular nature of the law established by the Treaties, ensured by the preliminary ruling procedure provided for in article 267 TFEU, and is not therefore compatible with the principle of sincere cooperation» (para. 58). The judgment is certainly to be welcome, it will have important consequences on the future of the intra-EU investment agenda, and may have some impact also on the extra-EU investment agenda (see infra, § 5). It finally clarifies a series of important legal questions which had often been raised in the last decade before investment arbitration tribunals seized under relevant intra-EU BITs or under the Energy Charter Treaty, that probably lacked an adequate EU law perspective.