Despite the critical importance of applicable law in international arbitration, the concept remains misunderstood and often ignored. In the field of international investment law, whether the arbitration proceedings arise from an investment treaty or from a contract, the cornerstone principle of party autonomy applies when it comes to the choice of applicable law, as provided, for example, in article 42 of the ICSID Convention. Even that principle, however, is subject to debate, for example with respect to whether initiating arbitration proceedings under an investment treaty amounts to an implicit choice of applicable law. In an attempt to clarify the notion of applicable law, this contribution first distinguishes the rules of decision, i.e. the law applicable to the specific claims submitted by an investor against a state, from incidentally applicable law, i.e. the other laws which may be relevant for the resolution of the dispute but that do not form a basis for the decision on the merits. In a second part, this contribution analyses several questions arising from the application of choice-of-law provisions in practice, with an emphasis on article 42 of the ICSID Convention. Finally, the consequences of erring in the application of the correct applicable law are examined.

The multi-faceted role of arbitrators is complex and protean. While there is consensus on the fact that the nature of the international arbitrator’s role entails according the arbitrator wide-ranging powers and that the arbitrator also undertakes a panoply of obligations, the scope of these powers and duties is not always well defined.Views about the nature and scope of these powers and duties might diverge depending on whether arbitrators are seen as service providers, justice purveyors, or both. Following a brief overview of this core question, the contribution proceeds to identify the sources of an arbitrator’s powers. Next, the most important duties of international arbitrators, including those pertaining to ethical obligations, the need to ensure due process, the necessity to apply the proper law, the duty to provide a reasoned award, and several others are explored. This contribution also highlights the most important rights of international arbitrators, such as the right to receive good faith cooperation from the parties, as well as the rights to remuneration and immunity, amongst others. Finally, we make some observations on ways in which the rights and duties entailed by the complex mandate of arbitrators can be reconciled in the event of conflict.

This chapter addresses the vital issue of which law which should apply to substantive proceedings between parties to derivatives contracts. The discussion presumes that the jurisdiction of the English courts has been chosen or otherwise settled, as discussed in the Chapter 8. Accordingly, the impact that a contractual choice of law may have on disputes about jurisdiction is not addressed here.