Truth at any cost?

The admissibility of illegally obtained evidence in international arbitration

Abstract

This article examines the admissibility of illegally obtained evidence in international arbitration, starting from the broad evidentiary discretion afforded to arbitral tribunals and the generally liberal approach of arbitral practice. On the basis of case law and the IBA Rules on the Taking of Evidence in International Arbitration, it identifies a structural rule: illegally obtained evidence is, in principle, admissible unless specific grounds for exclusion are established. The article distinguishes between cases in which the party has participated in the unlawful procurement of the evidence — in which situation the evidence should, as a rule, be excluded — and cases in which the illegality is attributable to third parties, where a balancing of interests is required. It argues that the true foundation of these solutions lies in the protection of the integrity of the arbitral process and proposes a stepwise test that articulates lawfulness, relevance, materiality, reliability and the parties’ conduct.