CIArb Features

Heated Debate: Giving Evidence in the Hot Tub

11 Oct 2018

What is witness conferencing?

Witness conferencing is used to describe the taking of oral evidence from multiple witnesses concurrently. Described by one leading arbitrator as a ‘novel evidentiary process’, it is mostly, but not exclusively, used when expert witnesses give evidence. Witness conferencing is recognised in (among other things) the IBA Rules on the Taking of Evidence in International Arbitration, and the ICC Commission Report on Controlling Time and Costs in Arbitration.

Witness conferencing is not, however, a single defined procedure. For example, some tribunals take the lead in questioning the witnesses with limited involvement of counsel. At other times, the process can involve a mix of traditional cross-examination by counsel and a panel discussion among the witnesses of the issues in dispute. One of the attractions of witness conferencing is its adaptability to suit the nature of the dispute, the types of issues and even the individual witnesses.


Why might parties employ witness conferencing as an evidence-taking process? One of the main perceived advantages is its effectiveness. Evidence given in conference is often presented on an issue-by-issue basis. Rather than each party’s counsel cross examining the opposing party’s witness on a given topic when each party presents their case, the witnesses themselves may respond to their counterpart’s views as they are presented, allowing differences to be articulated and tested on the spot. This side-by-side presentation of evidence makes it easier to compare the witnesses’ different views. It can also lead to a more rigorous inquiry into the evidence, since witnesses can hear each other’s opposing views and challenge those views with direct responses or rebuttals.

Concurrent witness examination may also improve the quality of witness testimony. Some attribute this to the fact that witnesses do not appear alone, which creates a more relaxed environment in which people feel more comfortable giving evidence. In addition, expert witnesses are likely to be more reluctant to make incredulous or technically incorrect statements in the presence of a peer who can provide an immediate rebuttal.

Finally, witness conferencing may lead to improved efficiency of the evidence-taking process. Although this view is not universally shared, many take the view that the process saves on the overall time and costs of a hearing citing the ability to present evidence on issues in a logical and consistent manner by the witnesses, as opposed to issues being addressed multiple times by different witnesses. Others, however, take the view that the time and cost savings may only be in respect of avoiding repetition at the hearing, whereas the witnesses may need to engage in lengthier pre-hearing preparation in anticipation of the conference.


Witness conferencing gives rise to dynamics that do not arise where witnesses are subject to traditional cross examination in the common law style. Arbitrators, parties and experts should be aware of these dynamics where the taking of concurrent evidence has been ordered.

For example, the concurrent attendance at a hearing means that interaction between the witnesses will be unavoidable. Sometimes, unfriendliness or hostility among witnesses may affect their presentation of evidence. In extreme cases, a witness might respond to another’s evidence with an audible laugh, or the witnesses may even exchange insults. A numerical imbalance of witnesses giving evidence on behalf of the parties may also create or appear to create an advantage for the group of witnesses that outnumber the others.

There are also other less obvious ways in which witness interactions may affect the evidence given, such as when a naturally charismatic witness dominates the discussion, whose evidence is not properly substantiated, but which is not rebutted by the less charismatic witness. Another situation that may arise is when one witness exerts an influence over another. This dynamic, often subtle and not always easy to discern, can arise from a variety of relationships, whether due to cultural factors, pre-existing professional relationship between the witnesses, or otherwise. Tribunals and parties need to be aware of how these dynamics can affect the evidence given by the witnesses.

Finally, the concurrent appearance of witnesses can alter the balance of control over the proceedings. Whereas parties’ counsel dictate the direction and pace when testing of evidence in traditional cross examination, the witnesses and the tribunal typically exert a greater degree of control in a witness conference. The presence of multiple witnesses generates a higher degree of unpredictability in that exchanges between witnesses can cause the direction of questioning to unfold in ways that counsel cannot control as readily. The freer flow of competing views in concurrent evidence therefore often requires greater interaction from the tribunal than during cross examination.

The Singapore branch of CIArb has established a sub-committee on witness conferencing in international arbitration looking into the above and other related issues. Timothy Cooke, together with David Isidore Tan and James Church-Morley who assisted in preparing this article, are part of that sub-committee.