Forms of evidence

As seen above, documents in support of a party’s case are normally served with that party’s written pleadings/submissions. Each party may then make requests for production of any additional documents that it considers should be disclosed. A detailed discussion of such disclosure/discovery will be found, below, in this module. It should be noted, though, for present purposes, that an arbitral tribunal often deals with how and when any requests for documents should be made in its procedural directions.

The four principal forms of written evidence in an international arbitration are:

1. factual witness statements
2. contemporaneous documents
3. expert report(s) (appointed by the parties or the arbitration tribunal), and
4. site visit or subject matter inspection.

However, some will subdivide as follows (mirroring the range of evidence and material that will be seen in litigation):

1. oral testimony of witnesses of fact
2. written testimony of witnesses of fact
3. oral opinion evidence of expert witnesses
4. written evidence (typically in the form of a report) by expert witnesses
5. contemporaneous documents
6. real evidence (including objects and items and the inspection thereof), and
7. inspection visits to a physical location.

Factual witness statements

Witness testimony is the principal form of fact finding. Subject to any particular procedures agreed by the parties, the tribunal will have control over the procedure in relation to witnesses giving oral evidence ensuring, as a fundamental duty and principle, the equal treatment of the parties. It should be noted that, in an international arbitration, any person (including the parties and their legal representative) is generally permitted to testify as a witness.

Expert evidence

Where expert evidence is required, the parties may agree there should be a single tribunal appointed expert or, on the other hand, each party may instruct its own. Where each party has instructed its own, the expert’s statement or report will be in writing and will be exchanged as between the parties according to a timescale agreed at the preliminary meeting. The tribunal itself will, of course, receive a copy of the report or reports.

The usual process is the report will be taken as the expert’s examination sheet and, therefore, oral testimony will be confined to cross-examination or, sometimes, limited additional questions in chief or matters that could not be addressed in court. There will then, ordinarily, be an opportunity for the party to calling the expert to re-examine on any matter that has arisen in cross-examination. There may be circumstances where the parties do not intend to call their own expert, but the tribunal is of a view that expert evidence is required. In such circumstances, subject to the specific arbitration law of the seat, the Model Law approach, as set out in art 26(1)(a), provides that “unless otherwise agreed by the parties, the arbitral tribunal may appoint one or more experts to report to it on specific issues to be determined by the arbitral tribunal”. It is not unknown, however, in circumstances where a tribunal has appointed an expert, that having seen that expert’s report, they then each instruct their own expert.

Where a single tribunal expert is to be used, an arbitral tribunal will normally determine issues as to the obtaining/service/admission of expert evidence in agreement with the parties in a procedural order addressing evidentiary matters.

Generally, where there are two (or more) experts, in order for any issues between them to be narrowed as much as possible, it is usually the case that the experts will meet before an arbitration hearing in order to discuss the matter and, in practice, to seek to agree on some common ground. In addition, as a useful case management tool, an arbitral tribunal, in consultation with the parties, will often provide a note to the experts that sets out the issues that remain live between the parties and require address by expert evidence.

To assist parties and tribunals, the Chartered Institute of Arbitrators has issued it Guideline 7: Party Appointed and Tribunal Appointed Expert Witnesses (2016).

Site or subject matter inspection

An arbitral tribunal has discretion to order a site or subject matter inspection, unless the parties have excluded such power. Article 7 of the International Bar Association Rules on the Taking of Evidence (2010) (IBA Rules) provides for on-site inspection “the Arbitral Tribunal may, at the request of a Party or on it on its own motion, inspect or require the inspection by a Tribunal-Appointed Expert or a Party-Appointed Expert of any site, property, machinery or any other goods, samples, systems, processes, or Documents, as it deems appropriate”.