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My Expert – Should I allow him to go “Hot Tubbing”?


One of the central planks of the report by Lord Woolf, “Access to Justice”, which preceded the introduction of the new Civil Procedure Rules about 12 years ago, was His Lordship’s concern about the misuse of experts in the conduct of litigation. Quite rightly, he criticised the extent to which, at that time, experts were mere “hired guns” called to do all they could to support and advance their client’s case, not called on the basis that they would share their expertise in a neutral way with the court at trial. As a result, experts were subject to aggressive cross-examination in an attempt to shoot down what they had to say. In consequence, in a highly charged atmosphere, the judge was left with the unenviable task of trying to decide which of two experts he found more persuasive in circumstances where the subject matter of their expertise was very probably something about which he knew little or nothing. Unsurprisingly, Lord Woolf regarded this situation as entirely unsatisfactory.

The Civil Procedure Rules on Experts

Experts who give evidence to the court have to comply with Part 35 of the Civil Procedure Rules. These require the expert to certify that he recognises his primary duty as expert is to the court and that it is the duty of the experts to assist the court (not the party instructing them and paying them). Nevertheless, even though there have been substantial changes in the obligations that expert witnesses have to bear, the ordeal of examination and cross-examination remains central to the courts’ task of deciding which of competing experts’ evidence is to be preferred.

Apart from this, an unhappy trend now being seen is for the court to allow the parties to call several experts, each with a particular area of expertise, notwithstanding the court’s powers under CPR 35.4 to restrict expert evidence. Inevitably, the use of several experts increases the costs dramatically and one does wonder whether this practice increases the probability that the judge will get the decision “right”.

Hot Tubbing

In an attempt to remove, or at least lessen, the Punch and Judy approach to litigation – “Oh yes it is”, “Oh no it isn’t!” – the Australian courts have led the way in an alternative way of taking expert evidence at trial. This is the so-called “concurrent evidence” approach which has acquired the nickname of “hot tubbing”.

The procedure is that the experts (let us assume two) go into the witness box at the same time. The judge puts the questions to the experts, at the same time, and the parties must put questions to them through the judge.

Immediately, this changes the dynamic of this part of the court process. The judge may encourage the experts to ask each other questions and, in an echo of mediation procedures, it is to be anticipated that the experts by this process will find areas of common ground. In this way, it is probable that the parties, will much more quickly identify the true issues for determination in the case. It is well known that nearly all cases boil down to at most two or three central issues to be decided.

Lord Justice Jackson

In his recent magnum opus, “Review of Civil Litigation Costs: Final Report”, Lord Justice Jackson has recommended that hot tubbing be piloted in cases where all the parties and the judge agree to it. It remains to be seen whether the process will find such favour that judges will be given the power to order that there be hot tubbing, even in cases where the parties disagree as to whether this is appropriate.


Savings of time and costs. In the present economic climate, anything that saves time and costs in connection with litigation (or arbitration) is to be welcomed. Because of the hot tubbing concept, experts are more free to answer questions in a way which the court will find useful and less likely to be confined to the “script” imposed by their witness statements, these having often had substantial input from others apart from the experts themselves.


In circumstances where the Government seems intent on driving most of the population from the courts by abolishing legal aid, and where the courts are fast becoming the playgrounds of only the wealthy, anything that can be done to make the handling of disputes more efficient must be done. The experience from Australia is that the hot tubbing procedure is a success. In all probability, we will be seeing much more of this both in the courts and in arbitrations in the coming years.


This briefing is for guidance purposes only. RadcliffesLeBrasseur LLP accepts no responsibility or liability whatsoever for any action taken or not taken in relation to this note and recommends that appropriate legal advice be taken having regard to a client's own particular circumstances.