Can the European Union Serve Two Masters? Revisiting the Conflict Between EU Treaties and Investment Agreements Under the Law of Treaties

The present research makes the case for a revisitation of the intra-EU saga under the law of treaties. To do so, it briefly retraces the main chronological stages of this never-ending story, choosing to focus on the interaction between EU treaties and the Energy Charter Treaty (ECT). Afterwards, it shows that investment tribunals failed to identify and resolve the normative conflict between these two treaties because they unsatisfactorily approached the problem as a ‘clash of constitutions’. Second, it is argued that also the recent Green Power v. Spain award — in which the intra-EU objection was upheld for the first time — offered a rather unconvincing solution. However, it is submitted that the European Union itself has long hindered the settlement of the issue, constrained as it is by its strategy of ‘selective engagement’ with international investment law. The definitive end of the intra-EU saga necessarily involves abandoning this strategy.