When contemplating dispute resolution for complex construction projects, the role of the expert is an essential consideration. One expert-centered approach to expert presentation that has gained significant notoriety internationally is what is most commonly referred to as concurrent expert testimony or “hot tubbing” expert witnesses. This paper explains the hot-tub process and then explores how lessons learned from the hot tub’s emphasis on expert participation in determining a dispute’s outcome can be adapted to alternative ADR methods to make them more effective in quickly and efficiently resolving matters.


The Potential Benefits And Disadvantages Of Hot Tubbing


Experts play a critical role in litigation and ADR proceedings, particularly where complex technical issues are in dispute. Experts are retained to explain the technical or scientific elements of a case that exist outside of the judge’s and attorneys’ purview.  Also, unlike lay witnesses, expert witnesses may rely upon specialized knowledge when testifying.  Yet, the way experts are employed in typical American litigation may fail to make the best use of their knowledge and expertise.

Under traditional American trial and ADR proceedings, each party in a lawsuit selects its own expert witnesses.  One party then presents all of its evidence on all relevant issues before the opposing party has an opportunity to provide its opposing opinions and evidence.  Thus, the testimony of the opposing experts may be separated by days, weeks, or even months.  This approach may make it difficult for the fact-finder to compare the opposing expert opinions or to identify any issues on which the parties agree.

Inherent in the adversarial American system of dispute resolution, where experts are chosen by the opposing parties, is the perception of bias in the opinions reached by the expert witnesses.  This perception is further exacerbated when the experts on opposing sides come to polar-opposite conclusions, leaving the trier of fact to weigh sharply conflicting opinions on highly technical and complex issues.  Consequently, a fact-finder that is unable to fully understand or reconcile opposing opinions may decide to reject both opinions and decide the matter on more arbitrary grounds, such as which expert is more qualified or which expert was able to state his or her opinion more simply and concisely.

Indeed, fact-finders are often resigned to the fact that each party will present the expert witness most favorable to his or her client’s position regardless of whether it is useful or not.  Ultimately, this common expert-based approach in adversarial proceedings leaves the fact-finder with an ineffective mechanism for assessing the merits of expert opinions.  Also, the expert witness is often forced to struggle between his or her role as the expert or the party advocate.

One way to resolve this issue is to permit experts to testify concurrently from the witness stand.  In other words, instead of proceeding sequentially during a party’s case, both sides’ experts sit together and discuss the relevant issues with each other and the fact-finder under oath. This process is known as “hot tubbing,” and it is currently used by courts in Australia and New Zealand and increasingly in international arbitration.

This hot tubbing process is unique in that it allows each side to still have a say in the process of selecting an expert witness.  However, it also cuts down on the potential for bias by the experts and allows the trier of fact to more effectively hear and understand the expert testimony being presented in the dispute.

Origins Of Hot Tubbing


Hot tubbing has its roots in the Australian Competition Tribunal and is sometimes considered the “Australian approach” to expert testimony.  It became popular among Australian judges because of its design to remove partisan advocacy from expert testimony.  Moreover, many judges, attorneys, and commentators note its potential to remove tension during testimony and allow experts to better respond to their colleagues, rather than simply answering the opposing lawyers’ questions.  Consequently, hot tubbing has become more popular throughout Australia and has officially been introduced into the Rules of the Federal Court of Australia, the Uniform Civil Procedure Rules for the Supreme Court of New South Wales, and the Court Rules of the Victorian Supreme Court.

Hot tubbing has expanded beyond just Australia. Canada, for example, has introduced expert hot tubbing into its Competition Tribunal Rules for use in contested antitrust proceedings.  In the United States, courts have even occasionally used hot tubbing in the trial setting for an assortment of different cases, including those involving breach of contract, products liability, and patent infringement.  The use of hot tubbing outside Australia, however, remains somewhat infrequent.  Regardless, hot tubbing provides practitioners a potential method to simplify and expedite expert testimony in litigation, especially in the context of ADR.


How Hot Tubbing Works


While there are different variants of hot tubbing, there are several key elements of the process that tend to appear in each version. Typically, hot tubbing begins with the preparation of written expert reports, which are then exchanged between the parties prior to the experts’ testimony. Often, the experts then “meet and confer” in order to prepare a joint report about the topics on which they agree or disagree. This process is intended to reduce the issues remaining in dispute and subject to expert testimony.  Lawyers generally are not present at these “meet and confer” sessions.

Experts that do end up testifying at a hearing generally conduct their testimony after both parties’ cases-in-chief have been heard and all the lay witness testimony has been offered.  They also typically testify together or directly after one another.  Generally, the plaintiff’s expert will start with a brief discussion and then will be questioned by the defendant’s experts without the intervention of counsel.  The process is then reversed to address the defendant’s experts.  Finally, at the end of this stage, each expert is afforded the opportunity to present a brief summary of their positions.

Once this initial step is complete, the attorneys are usually provided the opportunity to cross-examine experts.  Even in this cross-examination stage, experts are allowed to continue questioning one another and adding to other expert testimony.  This stage of the hot tubbing process allows attorneys and experts to discuss and distinguish conflicting expert testimony, hear from each side simultaneously, and have the opportunity to defend and further explain their own evidence.

Notably, the actual hot tubbing itself tends to be an informal process.  The arbitrator or mediator may ask an expert to comment or ask questions about an issue in the case or to address a point raised by another expert.  Only one expert speaks at a time during this process, which promotes a respectful and constructive dialogue among the experts.  Also, the lawyers and experts are able to pose questions to different experts during the discussion phase.  Fundamentally, the idea behind hot tubbing is to foster a collective dialogue that simplifies the fact-finder’s role in assessing the contentions of either party. In many ways, this process represents a significant departure from the typical adversarial type of expert testimony that is so prevalent in courtrooms and ADR proceedings today.

Is Hot Tubbing Permissible?


Before hot tubbing can be introduced into courtrooms and ADR throughout the United States, it is important to understand whether such concurrent testimony is even permissible under applicable rules of procedure. The Federal Rules of Evidence provide a framework that allows the practice of hot tubbing by providing the court the power to manage the presentation of testimony and to question witnesses.  Indeed, there is no prohibition in the Federal Rules of Evidence that prevents the use of hot tubbing in the courtroom.

Similarly, there is no existing rule of arbitration that prohibits the use of alternative procedures for handling expert witnesses.  There are, however, international rules and protocol applicable to arbitrations that contemplate the possibility of hot tubbing.  Under the International Bar Association Rules, for example, there are numerous provisions designed to foster cooperation among experts in the pre-hearing stages of the arbitration.  One such rule states that “[t]he 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.”  Another Rule also provides the tribunal “complete control” of the presentation of testimony during the course of the evidentiary hearing.

Most notably, Article 8(2) of the International Bar Association Rules considers the use of concurrent expert witness testimony during the hearing.  In pertinent part, the rule holds 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 presented by different Parties be questioned at the same time and in confrontation with each other.”  Accordingly, this rule permits all expert witnesses to be subjected to questioning at the same time as is done in the hot tubbing process.  As such, Articles 5 and 8 of the International Bar Association Rules envisage the use of hot tubbing to streamline and simplify expert testimonies.

Additionally, although the Chartered Institute of Arbitrators Protocol does not specifically mention whether expert witness conferencing may take place during the hearing, it does implicitly adopt the rules promulgated by the International Bar Association.  Further, the Chartered Institute of Arbitrators Protocol, akin to the International Bar Association, also permits conferencing at pre-hearing stages so that “before any hearing the greatest possible degree of agreement between the experts” is established.  Accordingly, the Protocol seeks to foster expert consensus by promoting the exchange of draft outline opinions and facilitating meet and confer sessions prior to the hearing.  Even during the hearing itself, the Protocol explains that “[t]he Arbitral Tribunal may at any time, up to and during the hearing, direct the experts to confer further and to provide further written reports to the Arbitral Tribunal either jointly or separately.”  While the Chartered Institute of Arbitrators Protocol may not be as straightforward as the Internal Bar Association Rules, it would seem the Protocol at least permits the use of hot tubbing should the arbitrator deem it appropriate.

Lastly, while arbitration through the American Arbitration Association (“AAA”) or in connection with a dispute before the Armed Services Board of Contract Appeals (“ASBCA”) or the Civilian Board of Contract Appeals (“CBCA”) may not expressly reference the use of hot tubbing, the arbitrators are granted broad authority to alter the proceedings to expedite the resolution of the dispute. Specifically, Rule 32 of the AAA Commercial Arbitration Rules and Mediation Procedures explains that an arbitrator has the authority to vary the procedure by which witnesses are examined “provided that the parties are treated with equality and that each party has the right to be heard and is given a fair opportunity to present its case.”  As for the various boards of contract appeals, the applicable forum rules and federal laws grant wide latitude for the arbitrator to conduct the arbitration in an informal manner that will yield expeditious resolution of the matter.

Given the broad discretion provided by the different methods of arbitration under international and domestic tribunals, hot tubbing certainly is a potential method of quickly and efficiently conducting expert testimony in both the courtroom and ADR.

Hot Tubbing in Practice

Although hot tubbing has tremendous potential, its use in practice is often limited by those implementing it. Attorneys may resist the use of hot tubbing because they do not want to relinquish their control over the adversarial process.  Also, given that the success of hot tubbing often rests on the arbitrator’s or mediator’s ability to structure and control the process, attorneys may be unwilling to abandon their conventional approach for this seemingly riskier method of expert testimony.  Indeed, hot tubbing may result in the fact-finder being persuaded simply by the more articulate or more authoritative personality, or may result in the expert inadvertently delivering a message that harms the client’s interests.  Thus, independent, neutral expert testimony usually only occurs in the United States where it is either imposed by the court, strongly recommended by the arbitrators, or agreed to because both parties believe the neutral testimony will be harmless or mutually beneficial.

Nevertheless, parties should be mindful of the distinct advantages and disadvantages concurrent expert testimony offers in trial and ADR settings. While an attorney may be hesitant to give up his or her control over the process, hot tubbing can certainly offer a more unique approach to expert testimony that may be more beneficial to his or her client in the long run. That said, hot tubbing also has several drawbacks that should also be weighed in light of the circumstances surrounding the trial or ADR.



Reprinted with the permission of AACE International, 1265 Suncrest Towne Centre Dr., Morgantown, WV 26505 USA. Phone 304-296-8444.



Copyright © 2017 by AACE International; all rights reserved.