As set out in blog post on evidentiary issues in international arbitrations, the treatment of evidence within the field of international arbitration is oftentimes inconsistent and even unpredictable from one arbitral tribunal to another, a divide which becomes even more pronounced when considering the different approaches that may be adopted due to a decisionmaker’s backgrounds in common law versus civil law. Our blog post argued that more uniformity in evidentiary rules—and ultimately in the interpretation of admissible evidence—in international arbitrations would reduce the subjectivity and seeming randomness of evidentiary decisions and in outcomes in different cases, leading to less arbitrariness in the system as a whole.

In this post, we highlight three evidentiary issues—the matters of legal privilege, hearsay, and illegally obtained evidence—on which there is significant divergence between (and even within) the common law and civil law traditions. In light of these variations across jurisdictions, we recommend that arbitral centers devise their own set of optional evidentiary rules bridging the evidentiary differences between civil law and common law traditions and reducing arbitrator discretion. The authors’ expectation is that this would ultimately increase predictability for parties that opt to use such rules.