ASSESSING EXPERT EVIDENCE - Chapter 30 - Leading Arbitrators' Guide to International Arbitration - Fourth Edition

Questions of increasing technical, scientific, or forensic complexity abound in international arbitration disputes. Arbitral tribunals, if they are to discharge their duty to render fair, reasoned, and enforceable awards, need the assistance of experts in the fields concerned. Assistance derived from expert testimony presupposes that the arbitral tribunal makes its own critical, informed, and independent assessment of expert evidence. That much is uncontroversial.

Matters start to blur, however, in those instances where the complexity of technical issues requires more than expert assistance, it crosses a threshold and becomes reliance on expert opinion by the arbitral tribunal.

Reliance on expert testimony is an acknowledged phenomenon, described by Judges Al-Khasawneh and Simma of the International Court of Justice as inevitable in certain intricate cases: “reliance on experts is all the more unavoidable in cases concerned with highly complex scientific and technological facts. (…) [T]echnical evolution has brought to surface the tension that inevitably exists between the legal conception of ‘fact’ and of evidence on the one hand, and the conception of facts in the sciences, on the other.” (Emphasis added)

This contribution explores some of the issues at the border between an international arbitration tribunal’s assessment of expert testimony, and its reliance thereon. Whilst significant progress has been made in the procedural presentation of expert evidence—be it by way of party-appointed experts, tribunal-appointed experts, expert witness conferencing (in-person or remotely), or a combination of the three—little has been said, in scholarship or in practice, on the consideration and assessment of expert evidence by the tribunal, and arbitration rules and statutes offer scarce guidance on the topic.