Last year, a federal district judge thought he had come up with a unique way of handling expert witnesses: forcing them all to testify and quarrel with one another at the same time. Under oath, in the courtroom, with the judge getting involved in the action too, the experts battled and refuted one another back and forth.

“[I]t was great fun for me (perhaps because I’m a former trial lawyer) to be engaged directly with the key testimony that I needed to rule on…” wrote U.S. District Judge Jack Zouhary about his atypical approach to the expert witnesses in a complex, antitrust class-action in Ohio. “It was great to have the experts in the courtroom at the same time, nearly face-to-face, with questions they could not duck, and to have the opposing expert comment on what he or she had just heard.”

One day after the trial, a lawyer approached the judge saying he heard the judge had been “hot-tubbing,” a term unknown to Hon. Zouhary.

“Hot tubbing” is slang for having “concurrent expert evidence” being offered simultaneously or sequentially by a “conclave” of experts. Note that not one of these above terms appears in Black’s Law Dictionary, and as was the case with Judge Zouhary, most American lawyers and judges have never heard of the practice.

Hot tubbing, however, is quite common in Australia, which is credited with inventing the method. It is gaining support in other nations as well, with the United Kingdom passing an amendment to its Civil Procedure Rules in 2013 to specifically permit its use.

While U.S. federal law does not specifically address the hot-tubbing concept, it does not prohibit it either. Federal Rule 611 give judges wide latitude with respect to expert witness testimony,  stating that the “court should exercise reasonable control over the mode and order of examining witnesses and presenting evidence so as to (1) make those procedures effective for determining the truth; (2) avoid wasting time; and (3) protect witnesses from harassment or undue embarrassment.”

When American companies are involved in high-stakes or complex litigation like antitrust or patent cases, the second prong above is of particular concern. Litigation can often take years, and legal and expert fees can become exorbitant.

“The conclave (hot tub) procedure has been required by [Australian] judges as a means of saving time and costs,” Australian Senior Counsel Ross McKeand says from his office in New South Wales, outside of Sydney. “Experience shows that experts who are opposed in their views may, surprisingly, agree under pressure when they (two or more) are giving evidence together in court and the judge is questioning them directly.”

Judge Zouhary agrees.

“The Australian courts deserve credit for this approach. Surveys of Australian judges found that 95 percent were satisfied with the procedure, felt it increased objectivity and quality of expert evidence, found it made comparisons easier, and enhanced the judge’s ability to fulfill the court’s role of fact-finding,” he explains.

However, while that may be easy in the case of a Daubert motion or Markman patent hearing before a judge, what if hot tubbing was used at trial before a fact-finding jury? The concern for Americans is a technique that seems to fly in the face of the U.S. adversarial system.

“The American system tolerates, if not encourages, the adversarial use of experts whose allegiance is to the party that retains them and whose opinions may only be cloaked in the rhetoric of objectivity,” according to the article, Room in American Courts for an Australian Hot Tub? published by the U.S-based international law firm Jones Day. “To reform the adversarial system in the United States by employing an evidentiary practice not fitted for its adversarial system could be a serious mistake. … If hot-tubbing has an American future … it should be used in very limited, non-jury contexts where the technical issues are so complex that a ‘discussion’ by the experts is essential for a rudimentary understanding of the dispute…”

However, Judge Zouhary does not see these perceived dangers to be so threatening to the American way of justice. He is eagerly looking for the right case to bring hot-tubbing in front of the jury, particularly if the case involves complicated technical information being espoused by experts.

“While its use in American courts appears to be limited to a bench trial or judicial fact-finding, it may also be helpful in trials where jurors have to make difficult decisions based on complex expert testimony,” Hon. Zouhary states. “Throwing everybody in the ‘hot tub’ at the same time allows the court, counsel, and experts to confront or, ‘splash,’ each other directly, resulting in a better chance of reaching a correct conclusion.”

So long as each party’s attorney is not barred from participation and examination, it’s hard to see why opponents find hot tubbing to be so adversarial to the adversarial system. 

“It normally works with both experts being placed in the witness box and each counsel being permitted to ask questions of both witnesses … with the judge both asking questions and varying the order of questioners throughout the hot tub,” explained Australian barrister Michael Maxwell. “So you may, for example, ask a leading question of your expert and then say, ‘What's wrong with that?’ to the opponent's witness.”

To some extent the hot-tubbing concept actually seems more adversarial than classic direct and cross-examination, allowing the battle to be fought between the experts rather than the lawyers themselves. The judge becomes the referee and the attorneys the bellowing coaches in the corner, so to speak.

Perhaps the only difference in that comparison is that, in the case of the hot tub, the referee and coaches get to jump in.

“In short, everyone gets a swing,” Hon. Zouhary sums up.

What are your thoughts on implementing hot tubbing in America? Under what conditions do you think it would work better than the existing process?