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  • Writer's pictureBrain Booster Articles


Author: Khuloos Aziz Chawla, pursuing LL.M. in ADR from Jindal Global Law School, O.P. Jindal Global University, Sonepat

The method of Concurrent Expert Witness or Hot-Tubbing originated in Australia and was initially practiced in Australian Competition Tribunal. From its application in Australian Trade Practices to officially being introduced in Federal Courts of Australia it became one of the most important rules throughout the world. This concept seeking much attention in the various court systems, is now also gaining a room in Alternative Dispute Mechanism.

Hot-Tubbing is a process of gaining the expert advice and the experts are sworn to give the competent opinion within their expertise capacity so that the same can be relied upon without any delay. It can also be called as “Concurrent Expert Witness” Tandem Expert” and “Dueling Experts”; these individuals that are stated as experts must be of the competent capacity in their respective field.It is a method where experts give their advice, and the arbitrator discusses it. When the written statements along with evidence are done then only experts are called upon to give their statements regarding the concerned issue. The experts can be called from both the sides, they present their facts and figures, and later arbitrator or leading counsels may ask questions relating to the subject matter. Also, the judge can ask questions in between but the rules of examining the expert witness may differ from each country.

How it is Different from Traditional Method of Evidencing?

Hot-Tubbing method in arbitration is very different from the traditional method of evidencing in litigation. The experts are made to testify from both proposing and opposing sides, they are brought together and are supposed to prepare their side of written reports. These reports are then exchanged, and they are directed to make joint statements together. This process eliminates the grounds of disagreement between the two and only present the summary of issues on which both the experts agree. Before the trial starts, both the parties produce an agreed agenda for taking concurrent evidence based on the joint statement. When the hearings start at the trial court, experts are sworn and placed in front of each other at the witness table. The issues on which there is a disagreement between the experts, those questions are directed to the arbitrator beforehand. The experts are encouraged to answer the questions addressed by their expert on the opposite side and the counsels. The cross-examination, re-examination or clarifying sessions can be done from these experts’ witnesses. However, the counsels’ participation is only restricted to raising objections and no questions on any other or new issues shall be asked.

Hot-Tubbing; Double-Edged Sword

Hot-Tubbing of experts is a double-edged sword as it has its own pros and cons. This process is rapidly growing in the field of arbitration as this method is more in tune of a dialogue rather than a verbal battle between the witness and the counsels. Arbitration itself is a speedy process and having expert’s opinion makes it easier for the tribunal to reach to the roots of the cause more constructively by investing less time and efforts. The tribunal dons the hat of the leader of the discussion as it supports impartiality, eliminates biasness, increases responsiveness and it is precise to only knowledgeable area by expert advice. Furthermore, the involvement of such competent persons ensures better assessment of the matter and highlights the discrete issues that needs coherence. On the other hand, the downside of Hot-Tubbing includes that it should only have the fully prepared experts, they should possess full knowledge of the subject matter and have skepticalanalyzing skills otherwise the whole meaning of expert advice will go in vain. Experts should be well trained with the court etiquettes to maintain the decorum of the court room as their demeanor plays a pivotal role and if it isn’t adhered to, then proceedings will not serve the true purpose. Experts ought to be formal and respective towards the arbitrator. Lastly, Hot-Tubbing makes the process of arbitration more costly as experts that are engaged also have their charges that are added and due to lack of formal examination during the whole process, the arbitrator might miss the key evidence.

International Recognition

Hot-Tubbing of experts is internationally gaining popularity and many arbitration tribunals worldwide have laid down their own rules for smooth application and promoting the expert advice. However, it is not mandatory under the process of any International Arbitration institution but a preferred act as it enhances the clear approach in the matter.

Hot-Tubbing has gained the legislative meaning as International Bar Association (IBA) in its Rules of Evidence in International Arbitration 20201recognizes the terms such as “Expert Report”, “Party-Appointed Expert” and “Tribunal Appointed Expert”. Also, Article 5(3A) of IBAstates that “the Arbitral Tribunal in its discretion may order that any Party-Appointed Experts who have submitted Expert Reports on the same or related issues meet and confer on such issues. The Article 8(4)(f) of IBA has directly mentioned the Hot-Tubbing by stating that “the Arbitral Tribunal, upon request of a Party or on its own motion, may vary this order of proceeding, including the arrangement of testimony by particular issues or in such a manner that witnesses be questioned at the same time and in confrontation with each other (witness conferencing)”.The rules also provide the various methods for the testimony of the experts at the evidence stage.

Chartered Institute of Arbitrators (CIArb) has published the Guidelines for Witness Conferencing in International Arbitration2. The rules aim to provide a non-exhaustive checklist of the factors that are to be considered in establishing a procedure that will govern the efficient and effective taking of evidence from experts. These are basically the procedural orders that can be used as the criteria for appropriate administrative directions for witness conferencing.

Apart from Australia where this practice was originated, the Canadian Evidence Act3 and Canadian International Trade Tribunal4 (CTT) Rules recognise the concept of expert witness. The CTT Rules give the discretion to the tribunal to testify the experts and promote the open discussion and question relating to the facts in issue. There are proper rules laid down to establish the method of Hot-Tubbing of expert witnesses.

Indian Perspective

The concept of Hot-Tubbing is a well-known method in Indian. The Section 45 of Indian Evidence Act 18725 acknowledges the expert’s opinion. The law stipulates the grounds as to when the experts can be referred for the advice, such as the issues relating to science, handwriting, foreign law, art or any other. Accordingly, experts shall be the skilled personnel whose opinion are valued but are not conclusive. Similarly, the opinion as well as the expert itself can be cross-examined.

Hot-Tubbing is also permitted in the commercial dispute as according to the amended Delhi High Court (Original Side) Rules, 20186, Section 6 under Chapter XI. These rules empower the court on its own or by the application of parties to permit the testimony of experts by the way of witnesses. The mechanism to regulate the process is mentioned under Annexure G of the rules and court may in its discretion mould the process according to the need of the dispute.

The landmark case in which Hot-Tubbing was addressed by the Delhi High Court was Micromax Informatics Limited vs Telefonaktiebolget L M Ericsson7. In this case courtemphasized on nature and scope of Hot-Tubbing as the dispute was related to Patent Law wherein parties had the wish to adopt the method of Hot-Tubbing. The court stated that “With respect to the procedure that can be used to arrive at a swifter resolution of disputes (such as in patent cases, involving technology and scientific experts‟ testimony and evidence), this court is of the opinion that patent disputes and those that involve examination of expert evidence should adopt the hot-tubbing procedure.”


Hot-Tubbing is the process that is still emerging and is in the middle of the road to the way of development in International Arbitration. There is an immediate need to make the procedures more stringent to take experts advice ‘mandatory’ in the matters needing professional opinion. The International Arbitration Institutions should adopt rules relating to application of the expert advice if it is the requirement of the case. Being a growing scenario, it will surely create an ease for the courts and tribunals.

With the rapid growth of this concept in India, Arbitration and Conciliation Act 1996 needs to have the concrete provision relating to Hot-Tubbing. However,Section 19 of Arbitration and Conciliation Act 19968mentions that the tribunal is not bound by the procedural or evidentiary law of the country and the parties are free to agree on the procedure to be followed by the arbitral tribunal. This section indirectly creates the advantage of taking the expert advice in any of the given scenario. In the nutshell, India is making its way in adapting the concept of Hot-Tubbing as it is evident from the rules of the Delhi High Court, but Indian legal regime needs more restrictive paradigm shift to make it a combative model in future for the world.



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