5 May, 2012


Legal News & Analysis – Asia Pacific – Singapore – Dispute Resolution




Expert witnesses play an important role in complex technical disputes, where the arbitral tribunal (“Tribunal”) will rely heavily on experts to assist, educate and advise them. Indeed, the outcome of a case may hinge on the ability of an expert to convince the Tribunal of the merits of his position.


Generally, international arbitration rules give Tribunals a broad discretion to determine how they wish to receive expert evidence. Increasingly, Tribunals are opting for expert witnesses to adduce their evidence through a process colloquially known as “hot-tubbing”, a procedure that is perceived to have several advantages over other more traditional methods.


This growing recourse to hot-tubbing adds another dimension to the role of experts in arbitration and informs the parties about the qualities that they should look for when appointing experts to testify on their behalf.


Hot-tubbing played a significant role in a recent Singapore International Arbitration Centre (“SIAC”) arbitration held in Singapore before a 3-member tribunal which involved a dispute arising out of a large infrastructure project (“Arbitration”). Each side required testimony from 3 to 4 engineering experts, with each expert specialising in different engineering disciplines. Cavinder Bull, SC and Chia Voon Jiet were co-counsel for the Claimant while lawyers for the Respondent instructed a Queen’s Counsel from London.




Hot-tubbing has its origins in Australian trade practice cases. As its name suggests, it involves the expert witnesses from both sides testifying simultaneously on the witness stand. This allows the Tribunal the opportunity to observe and assess the experts together in the proverbial “hot-tub”, instead of having to compare the testimony of experts who have taken the stand at different times.


Another distinctive feature of hot-tubbing is that the experts for both parties are expected to pose questions to each other without the intervention of counsel, thereby requiring each expert to identify weaknesses in the positions of the other, as well as defending their respective positions on the various issues in dispute. Depending on the experts, this may be more effective than traditional cross-examination as the questions, coming from the experts themselves instead of the lawyers, is sometimes perceived as being more credible. Experts faced with the prospect of being confronted by their professional peers may also be more candid and less partisan in their responses.


While counsel for the parties are also given the opportunity to ask questions of the experts, this is not done by way of the traditional cross-examination of the opposing side’s expert. Instead, questions will be posed to the experts who are seated together in the witness stand, and even if a question is posed to only one expert, the other may also respond if he or she so wishes. The Tribunal may also direct questions to both experts. This procedure may be more helpful to a Tribunal because the quality of the expert’s evidence is less likely to be influenced by the skills of the lawyer conducting cross-examination.




In the Arbitration, the Tribunal adopted a variation of hot-tubbing, and ordered that expert evidence be presented in the following manner:


(a) Each expert would make a presentation to the Tribunal.

(b) After the presentations, each of the expert(s) may ask questions of the other side’s expert(s) and also react to statements made by them.

(c) This is followed by questions from both counsels.

(d) The Tribunal may pose questions in the course of any of the above.


The adoption of the above procedure meant that the whole process of adducing expert evidence became more dynamic and interactive, more akin to a faculty symposium. Thus, the emphasis here was weighted towards the merits of the experts’ opinions as opposed to the skill of the lawyer in cross-examination.




Hot-tubbing may appear to result in counsel losing some degree of control over the presentation and testing of expert evidence. However, this process significantly enhances and elevates the role of the experts in arbitration proceedings. The expert who can effectively engage the Tribunal can be decisive for the case.


Hence, in any arbitration where hot-tubbing is anticipated, special care must be taken when appointing the experts. An expert’s reputation in his field of study becomes only one of several factors that parties will have to consider.


As the expert is expected to ask questions of the other side’s expert, the expert partially assumes the role of a lawyer during cross-examination, and should be comfortable with preparing and asking difficult questions of his professional counterpart. Ideally, the expert should also be able to think quickly on his feet, and react appropriately to the responses given by the other expert.


Further, where an expert is required to give an oral presentation to the Tribunal, as was the case in the Arbitration, oratorical skills become important. Someone who is articulate, confident and persuasive will have an advantage over another who lacks these qualities. For highly technical issues, the expert’s ability to explain complicated concepts in a way that is easy for the Tribunal to understand becomes crucial. These are factors that have to be borne in mind when selecting an expert witness.


Once the identities of both side’s experts are made known, it is also useful to ascertain beforehand whether the experts are acquainted with each other professionally, as their knowledge about each other can sometimes work to the benefit (or detriment) of one expert. For example, during the Arbitration, one of the experts stated that he “appointed” the other side’s expert on behalf of a mutual client in another project, and that he would

leave the “actual process” to the other expert, thereby conceding that the other expert was more experienced and respected in that field.


Finally, experts with prior experience with hot-tubbing will also enjoy an advantage over those whose experiences are limited to traditional methods of receiving expert evidence, eg cross-examination.




Hot-tubbing is a flexible procedure that is well suited to international arbitration and is increasingly likely to be employed in future, given its perceived advantages and growing popularity with arbitrators. There are a few conclusions to be drawn from this experience.


First, appointing the right experts takes on an even greater importance than ever before, and is a crucial first step that should not be overlooked.


Second, experts must recognise that in a hot-tubbing procedure, they play an even more critical role than under traditional methods, and they must prepare accordingly.


Third, there is value in having counsel work closely with the experts to prepare for the hot-tubbing so that the expert evidence will be consistent with the legal case theory.



For further information, please contact:
Chia Voon Jiet, Director, Drew & Napier


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