5 March 2019

"Hot tubbing" in the English Courts – soaking up the Australian experience

In his 2009 Review of Civil Litigation Costs: Preliminary Report, Sir Rupert Jackson raised the possibility of introducing the Australian "hot tub" to the English Courts:

"One other matter which merits consideration is whether the Australian procedure, whereby opposing experts give evidence concurrently, might be included in the CPR as an option…I am told by the Federal Judges in New South Wales that this procedure works well in practice and leads to a saving of costs."

After multiple iterations, hot tubbing or, as the Civil Procedure Rules refer to it, "concurrent expert evidence", is now provided for in paragraph 11 of CPR Practice Direction 35.

A decade after hot tubbing was first proposed, Bryan Shacklady and Fred Bowman of Forsters' Dispute Resolution team reflect on its use in the English Courts and evaluate the merits of concurrent expert evidence.

What is hot tubbing?

Instead of following the traditional approach to hearing expert evidence (where experts take it in turns to go into the witness box to be cross examined), the Court can now order that the evidence of experts from like disciplines be given concurrently. If hot tubbing is ordered, the relevant experts enter the witness box to be questioned by all parties' advocates and the Judge at the same time. While in the hot tub the experts are also able to ask each other questions and get into discussions about the issues arising in the case. The Court may intervene as it thinks fit.

How does it work in the English Courts?

Practice Direction 35 gives a high degree of flexibility to the Court when adopting hot tubbing. It can be decided on:

  • at any stage
  • for some or all of the issues at stake
  • for some or all of the experts instructed in the case.

While the usual procedure is set out at paragraph 11.4, the Judge retains complete discretion to modify the process.

It is open to the Court to combine the hot tub with traditional expert evidence. In Unwired Planet International Ltd V Huawei Technologies Co Ltd and Ors [2017] EWHC 2988 (Pat), the Court used hot tubbing to address certain general questions prior to each expert being individually cross-examined in order to bring greater clarity to key issues.

Assuming the usual hot tubbing procedure is adopted, the relevant experts will head into the witness box at the same time to be sworn in/affirm together – this can be quite a squeeze in a case involving multiple parties! The Judge will then discuss each item on a prepared agenda with the experts and/or invite the experts to comment on, or ask further questions about, each other's evidence on any given issue. It is only at this point that the parties' advocates get their chance to join in by way of a condensed form of cross examination. Practice Direction 35 provides that the advocates' questioning should be directed only towards testing the correctness or seeking clarification of an expert's view and/or eliciting evidence on any issue (or on any aspect of an issue) that has been omitted from consideration during the Judge-led questioning.

What are the challenges and opportunities?

Hot tubbing brings a completely new dynamic to the conduct of court hearings - and some potential challenges. In cases involving multiple parties, there is scope for one expert to be "ganged up" on by the others. Instead of simply having to face cross-examination by each advocate in turn, he or she can also be subjected to questions and comments from the other experts, while at the same time having to respond directly to the Judge.

All of this makes the choice of expert even more important. For the inexperienced expert, being outnumbered and having to react under fire from multiple directions can feel daunting. Any lack of preparation or inattention to the detail will be more easily exposed by the expert's fellow professionals. The personality of the expert is also worth considering, because the hot tub can provide an opportunity for a particularly vocal expert to try to dominate the process.

On the other hand, experts feeling under pressure may appreciate having additional time to compose themselves while the other experts are speaking – a luxury they would not have during traditional cross-examination.

A time saver or a costly alternative?

The objective of hot tubbing is to reduce court time and thereby costs. While many of the members of the judiciary see its benefits, in Streetmap.Eu Limited v Google Inc [2016] EWHC 253 (Ch), Mr Justice Roth also highlighted that the "process involves considerable preparation by the court and effectively requires a transcript since the Judge is unable to keep a proper note while leading the questioning".

As such, while it might save "live" Court time, it can add to costs and will unquestionably place an additional burden on the Judge as he or she hears the case, although it may also mean that, having been more involved in directing the discussion, the Judge will be in a better position to weigh the expert evidence than would be the case with traditional cross examination. In a case where there is substantial disagreement between the experts, it must also be arguable that more Court time will be taken up while they argue with each other.

Concurrent expert evidence will not be appropriate in every case but, ten years after Sir Rupert Jackson proposed it, it is clear that the hot tub is here to stay.

Bryan Shacklady, Senior Solicitor, and Fred Bowman, Associate, work in our Dispute Resolution team.

"Dynamic, totally focused and punchy, the Forsters Dispute Resolution practice extends from complex private client disputes to multi-million pound international commercial claims. The firm is a real alternative to the Magic Circle."  
QC, Maitland Chambers
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