Substance and procedure in international arbitration
Abstract The distinction between substance and procedure in private international law has been subject to extensive debates among national courts and scholarly writings. The basic theme that procedural issues are governed by the lex fori, and substantive issues are subject to the lex causae, is widely accepted, although the boundaries between substance and procedure are not always clear. This article examines the application of the distinction between substance and procedure in the area of international arbitration, as regards both commercial cases and investment treaty disputes. It is argued that the distinction between substance and procedure has significant ramifications in international arbitration. The central (though not the only) aim of this distinction refers to the determination of the rules to be applied to borderline issues, such as evidentiary matters, interest, and limitation rules. Arbitral tribunals should have a considerable level of discretion in drawing the distinction. Specified points of guidance are suggested for common grayzone questions. Although the general principles concerning the substance/procedure distinction are similar in investment treaty arbitration and international commercial arbitration, material points of difference, such as the key role of public international law, may somewhat narrow the investment treaty tribunals’ discretion in respect of drawing the distinction.