Arbitration — Applicable law — Investment arbitration — Proceedings instituted by investor incorporated in one European Union State against another European Union State — Bilateral investment treaty between two European Union States — Whether compatible with European Union law — Whether European Union law forming part of the law to be applied by the tribunal — Seat of arbitration in a third European Union State — Jurisdiction of the arbitration tribunal

Expropriation — Investment — Bilateral investment treaty — Protection against expropriation — Provisions on fair and equitable treatment and full protection and security — Compatibility with European Union law

Relationship of international law and municipal law — European Union law — Relationship between rights accorded to investor under bilateral investment treaty and principles of European Union law

Treaties — Validity — Application — Successive treaties dealing with the same subject matter — Compatibility of legal regimes established by successive treaties — Vienna Convention on the Law of Treaties, 1969, Articles 59, 65 and 30 — Bilateral investment treaty and European Union treaties