The role of the expert witness in arbitration proceedings is in many ways the same as that of the expert in civil litigation proceedings.
Whether appointed by the parties or by the tribunal, an expert is required to give their independent opinion on the issue(s) referred to them. They would base this opinion on the facts presented to them, applying their expertise and experience.
The parties and the tribunal may question or challenge the expert, and the tribunal might decide which expert’s evidence it prefers or, in the case of a single expert, whether to accept their evidence.
While an arbitrator may have been selected for their relevant experience or expertise, typically this is to ensure the arbitrator has an understanding of the issues in the dispute. It is not intended to put the arbitrator in the role of an expert giving and relying on their own opinion in making their award.
The appointment of experts in arbitration can be a way to further educate the tribunal on a specific issue, as well as to offer a professional opinion.
An essential aspect of the UNCITRAL arbitration process concerns the powers of the tribunal. The UNCITRAL Rules provide the arbitral tribunal with wide-ranging powers concerning the conduct and timing of the proceedings, evidence, the issuance of awards, interim measures and more. Article 26 provides for an expert to be appointed by the tribunal itself.
Article 26 was significantly influenced and inspired by the corresponding article of the 1976 UNCITRAL Arbitration Rules (article 27) and indeed the wording of both articles is very similar.
The first drafts of article 26 hewed even more closely to article 27 of the UNCITRAL Arbitration Rules, with only minor differences between them.
Article 26 started to take its own form by introducing the principle that the ability of the tribunal to appoint an expert was subject to the contrary agreement of the parties.
This reflected the prevailing view arising from early discussions that parties should be able to preclude the tribunal from calling an expert at any time. This issue was to be distinguished from the question of whether a party could present the evidence of an expert witness in arbitration.
It was agreed that the arbitral tribunal should hear such expert witnesses as provided for in the UNCITRAL Arbitration Rules.
For further information, read the comprehensive commentary on the UNCITRAL Model Law on International Arbitration. Tomas Vail has contributed a chapter on tribunal-appointed experts to the book: