I got an email invitation today to a seminar where one of the speakers will be speaking on "hot tubbing" with expert witnesses. I decided immediately that I would need to hire better looking experts in the future if this was going to catch on.

In all seriousness, it turns out that "hot tubbing" of experts had its origin in Australian courts, and it is becoming something of a "hot" subject here in the U.S.  There’s an article in ABA Journal about it, and also an article in the New York Times.

What it means is that all of the experts on a particular subject are sworn in at the same time, and then sit as a panel to be examined jointly by the lawyers for the parties and the Court. The procedure even allows for one expert to question another expert directly. 

Given the way the procedure works, it makes sense that hot tubbing is also known as "concurrent evidence."  If you are interested in exactly how this procedure works, you can keep reading below.

Here is how Peter McClellan, the Chief Judge of the New South Wales Land and Environment Court described his favorable experience with hot tubbing in a presentation:

At the same time as the Court has moved to appoint experts, we have also changed the process by which expert evidence is given in Court. This is now done concurrently and all experts in relation to a particular topic are sworn to give evidence at the same time. What follows is a discussion, which is managed by the judge or commissioner, so that the topics requiring oral examination are ventilated. The process enables experts to answer questions from the Court, the advocates and, most importantly, from their professional colleagues. It allows the experts to express in their own words the view they have on a particular subject. There have been cases where as many as six experts have been sworn to give evidence at the same time.

For hearings in my court, the procedure commonly followed involves the experts being sworn and their written reports tendered together with the document which reflects their pre-trial discussion – matters upon which they agree or disagree. I then identify, with the help of the advocates and in the presence of the witnesses, the topics which require discussion in order to resolve the outstanding issues. Having identified those matters, I invite each witness to briefly speak to their position on the first issue followed by a general discussion of the issue during which they can ask each other questions. I invite the advocates to join in the discussion by asking questions of their own or any other witness. Having completed the discussion on one issue we move on until the discussion of all the issues has been completed.

Experience shows that provided everyone understands the process at the outset, in particular that it is to be a structured discussion designed to inform the judge and not an argument between the experts and the advocates, there is no difficulty in managing the hearing. Although I do not encourage it, very often the experts who will be sitting next to each other, normally in the jury box in the courtroom, end up referring to each other on first name terms. Within a short time of the discussion commencing, you can feel the release of the tension which normally infects the evidence gathering process. Those who might normally be shy or diffident are able to relax and contribute fully to the discussion.

This change in procedure has met with overwhelming support from the experts and their professional organisations. They find that they are better able to communicate their opinions and, because they are not confined to answering the questions of the advocates, are able to more effectively respond to the views of the other expert or experts. They believe that there is less risk that their expertise will be distorted by the advocate’s skill. It is also significantly more efficient. Evidence which may have required a number of days of examination in chief and cross-examination can now be taken in half or as little as 20% of the time which would have been necessary.

As far as the decision-maker is concerned, my experience is that because of the opportunity to observe the experts in conversation with each other about the matter, together with the ability to ask and answer each others questions, the capacity of the judge to decide which expert to accept is greatly enhanced. Rather than have a person’s expertise translated or coloured by the skill of the advocate, and as we know the impact of the advocate is sometimes significant, you actually have the expert’s own views expressed in his or her own words.

I am sometimes asked, particularly by advocates, whether concurrent evidence favours the more loquacious and disadvantages the less articulate witness. In my experience, the opposite is true. Because each expert must answer to their own professional colleague, the opportunity for diversion of attention from the intellectual content of the response because of the manner of its delivery is diminished. Being relieved of the necessity to respond to an advocate, which many experts see as a contest from which they must emerge victorious rather than a forum within which to put forward their reasoned views, the less experienced or perhaps shy witness becomes a far more competent witness in the concurrent evidence process. In my experience, the shy witness is much more likely to be overborne by the skilful advocate in the conventional evidence gathering procedure than by a professional colleague who under the scrutiny of the courtroom must maintain the debate at an appropriate intellectual level. Although I have only rarely found it necessary, the opportunity is, of course, available for the judge to step in and ensure each witness has a proper opportunity to express his or her opinion.