Admissibility of Evidence in International Arbitration

One of the many benefits of arbitration in international disputes is that parties are generally free to submit any evidence required to establish their respective cases.

The purpose of presenting evidence to an arbitrator, much like adducing evidence before the courts during litigation, is to assist the arbitrator in determining the truth regarding disputed issues of fact.

International arbitration hearings have rules of procedure, but they can also follow rules which might have been agreed upon by the parties. For example, an arbitration tribunal could decide whether to include or exclude a particular type of evidence on a basis that is only relevant to a specific case.

This post looks at the IBA Rules on evidence, what types of evidence can be admitted (and any guidelines on this), as well as summarises the importance of evidence in international arbitration.

When is evidence admitted?

In principle, evidence is admitted to an arbitral hearing if it is relevant and material.

Article 3.11 of the IBA Rules requires the party to, at least, “believe” in the relevancy and materiality of the evidence in question. The weight of the evidence, however, still depends on its credibility (i.e. its reliability and authenticity).

In order to satisfy its burden of proof, a party has to offer sufficient evidence, take into consideration the case as a whole, and ultimately prove its allegations.

Intentional gaps in any piece of evidence are left to be filled, ultimately, by the arbitrator.

IBA Rules on evidence in arbitration

The IBA Rules (the “Rules") on the Taking of Evidence in International Arbitration were written, “in order to provide an efficient, economical and fair process for the taking of evidence in international arbitration”.

The Rules were designed to supplement existing legal provisions, which is particularly key in international disputes, where parties may come from differing legal traditions.

In addition to guidelines on how to apply the rules to a particular case, consulting on evidentiary issues and what to do should conflict between rules arise (in Articles 1 and 2), the Rules provide a framework for the following types of evidence, which are summarised below:

Article 3: Documents

Often, the type of evidence that carries the most weight for the respective parties are the documents they rely on.

The IBA Rules specify the types of documents both parties are in a position to provide, as well as how those documents could be requested by a party who or which reasonably believes them to be in the other party’s possession, together with any relevant objection to those requests.

The article also informs one what to do in the event a particular document is in the possession of a third party or organisation, not party to the arbitration proceedings, and the steps towards taking any legal action required.

Article 4: Witnesses of Fact

Witnesses of fact can be identified by either party where they need to rely on oral evidence . Parties should identify witnesses and the subject matter of their evidence, and arbitrators will often specify a timeframe in which this should be done.

Parties, including their counsel, can interview their witnesses (or potential witnesses) to discuss their prospective evidence with them in advance of identifying a witness.

Article 5: Party-Appointed Experts

Parties can choose an expert to review specific aspects of the dispute. They must take into account factors such as the expert’s qualifications and whether they are independent of the party to be able to provide reliable conclusions.

They must also be able to provide reasons as to how and the bases on which the expert arrived at his/her conclusion(s). The Rules also stipulate what information or details should be included in the expert’s final report.

The arbitrator also has the power to request each party’s expert(s) to consult and to provide reasons for their agreement or disagreement on specific points in each other's report.

Article 6: Tribunal-Appointed Experts

Similarly, an arbitrator may appoint his own expert to report to him or her on specific issues.

Parties may object to a particular expert and provide reasons for doing so. Parties will also receive any information the expert provides in respect of the case, including the final report, as well as have the right to attend any inspections of evidence by the expert.

Article 7: Inspection

One of the experts above (whether tribunal or party-appointed) may inspect any site, property, machinery or any other goods, samples, systems, processes or Documents, as the tribunal deems appropriate.

Article 8: Evidentiary hearings

The 2020 revision of the Rules provided substantial clarification to ensure that any remote evidentiary hearing would be as fair as possible.

Essentially, witnesses giving oral evidence must not be improperly influenced or distracted, and the arbitrator can exclude any question to, answer by or appearance of a witness as he or she deems appropriate.

Article 9: Admissibility and assessment of evidence

The arbitrator ultimately decides the admissibility, relevance, materiality and weight of the evidence.

Evidence may be excluded by the arbitrator due to its irrelevance to the case, legal impediment, privileged nature or it placing an unreasonable burden on someone, to produce.

An arbitrator may also form conclusions based on the best available information he or she has. For example should a party not be able to provide a good reason for not producing a requested piece of evidence, the arbitrator may determine that the missing evidence is adverse to that party’s interest.

Summary

National courts often follow elaborate rules that govern the evidence admitted into court proceedings. However, the procedures for obtaining and submitting evidence – and the weight any piece (or a particular type) of evidence should be given – arguably play an even more important role in international arbitration.

This is largely because a case can rely heavily on documents that may not ordinarily be admissible in court. Arbitrators can also include or exclude evidence with particularly high-level, political or top-secret information, which may be against either party’s best interest to enter the public domain.

When developing a strategy for presenting a case in international arbitration, expert advice from experienced arbitrators and legal counsel should be sought in advance of any proceedings.

For further information and trusted legal advice regarding matters of international arbitration, get in touch with the team at Carlsons Solicitors.