Procedural Posture and Purpose

This document sets forth the Concurring Separate Opinion of Professor Raúl Emilio Vinuesa regarding the Tribunal’s Decision on Jurisdiction and Costs. While Professor Vinuesa concurs with the Tribunal’s ultimate conclusion that the intra-EU jurisdictional objection (the Achmea principle) is inapplicable and agrees with the dispositive findings upholding jurisdiction, he writes separately to articulate a divergent legal reasoning concerning the interpretation of successive treaties under Article 30 of the Vienna Convention on the Law of Treaties (VCLT).

Legal Issues and Analytical Reasoning

The principal legal issue addressed is the interplay between the applicable Bilateral Investment Treaty (BIT) and European Union (EU) law, specifically whether they relate to the "same subject matter" under VCLT Article 30. Professor Vinuesa rejects the Majority’s reliance on the International Law Commission’s concept of "different treaty regimes" to circumvent the application of Article 30. He asserts that such an approach lacks grounding in the authentic interpretation process mandated by VCLT Articles 31 and 32, and criticizes the Majority's reliance on arbitral precedents that failed to properly apply these interpretive rules.

Instead, the Opinion advances the position that the BIT’s investor-State dispute settlement mechanism operates as lex specialis. Professor Vinuesa reasons that this specific procedural right constitutes a deliberate departure from general dispute resolution rules and thus prevails over subsequent general international rules, including EU law, absent express derogation. Furthermore, he concludes that the Claimant’s acceptance of the Respondent’s offer to arbitrate crystallized an "acquired right" under international law, which cannot be retroactively vitiated by the subsequent Termination Agreement between the State parties.