A "hot-tub" is a large tub filled with hot aerated water used for recreation or physical therapy.
“Hot-tubbing”, “concurrent expert evidence” or “witness conferencing” is a method of giving overt testimony, in which both witnesses of opinion (or fact) give evidence simultaneously and the judges of the court, or arbitral tribunal, chairs a discussion between them.
The expert witnesses are ‘sworn-in’ together and sit in front of the tribunal, which puts the same questions to each expert witness in turn, effectively acting as the “chair” of a debate between those experts to get to the truth.
One theory behind its use is that the expert witnesses are more likely to make concessions and reach a greater degree of agreement in the hot-tub than under traditional witness box based cross examinations. In the hot-tub, the expert witnesses are generally more relaxed and can therefore have a more constructive discussion. No alcohol is involved!
When to be used:
When there is a significant disagreement between the expert witnesses.
Where the tribunal needs to be educated about the intricacies of the underlying case.
Pros and Cons
Easy determination of crucial issues due to an open and frank discussion
No more unclear answers. The experts clarify and there is no lack of clarity
Time and cost efficient
More useful as the expert witness is more likely to assist the tribunal to resolve the disputes
Better understanding for the tribunal
Likely to bring forward a settlement as both parties understand more clearly the strengths and weaknesses of their case
A single expert is better able to manipulate a discussion
Less room for advocacy and persuasion.