Introduction

3.01 As a general rule, documentary evidence is often afforded the highest level of credibility within international arbitration.1 The preference for the written word over oral testimony is not something unique to the modern era of international arbitration, but is derived from the practices and procedures of some of the earliest arbitral tribunals and commissions. International tribunals from the nineteenth and early twentieth centuries, including “mixed commissions”, often incorporated into their rules a stated preference for evidence to be submitted primarily in written form and, in one particular instance, actually prohibited the introduction of oral testimony save for exceptional circumstances.2 One of the foremost experts on early arbitral procedure summarised this practice by stating, “probably the most outstanding characteristic of international judicial procedure is the extent to which reliance is placed upon its written word, both in the manner of pleadings, and of evidence, but especially the latter.”3