What has changed?

Since 1 April 2013 parties seeking permission for expert evidence must:

  • identify the issues the evidence will address; and
  • provide an estimate of the costs of that evidence.

The order granting permission may specify the issues which the expert evidence should address.

The technique of concurrent expert evidence (which developed in Australia and is known colloquially as “hot-tubbing”) has also been introduced as an optional procedure to be adopted at the direction of the judge, ie whether or not the parties agree. The technique involves hearing evidence concurrently from the experts in a particular discipline, rather than having each expert give evidence and be cross-examined separately. At trial, the experts are sworn in at the same time and the judge chairs a discussion between the experts. Counsel join in the discussion and can put questions to the experts, as and when permitted by the judge, and the experts can put questions to each other.

How was the change implemented?

The change was implemented via amendments to Civil Procedure Rule 35 and the accompanying practice direction.

Why was the change introduced?

The requirement to identify the issues was aimed at encouraging a greater focus in expert evidence. Previously the requirement was just to identify the field in which expert evidence was required. This amendment makes it clearer what issues the experts need to address, and makes it less likely that time / costs will be wasted dealing with peripheral or unnecessary issues.

Regarding the costs estimate, the aim was to make it easier for the court to exercise its pre-existing power to limit the amount recovered from an opponent in respect of experts’ fees and expenses. This ties in with the introduction of procedures for judicial costs management (see “Costs management”) and the court’s greater focus on managing costs in advance rather than just retrospectively.

With regard to concurrent expert evidence, or hot-tubbing, an interim report on the Manchester pilot of the technique expressed the view that there are time and quality benefits to be gained from the use of the technique, particularly due to the efficiency of the process and the ease with which the evidence can be given and differences of view examined and assessed. It did however note that counsel generally considered the process less rigorous than traditional cross-examination.

What are the implications for commercial parties?

In seeking permission to adduce expert evidence, parties need to consider and identify the issues that evidence will address, rather than just identifying the field of expertise. This means that parties need to be clear from an early stage what issues need to be addressed by expert evidence, and that their chosen expert(s) are able to support the party’s case on the relevant issues. It also reduces the risk of wasting time and costs with experts addressing peripheral or unnecessary issues.

With regard to hot-tubbing, this gives parties an additional technique at their disposal where it is felt that this will assist in presenting and testing the evidence. There is however a perception that hot-tubbing has not been widely used since its introduction in the Practice Direction to Part 35.

In August 2016 the Civil Justice Council published a report on Concurrent Expert Evidence & ‘Hot-Tubbing’ in English Litigation since the ‘Jackson Reforms’. The report was produced by a working group chaired by Professor Rachael Mulheron of Queen Mary University of London, with Maura McIntosh of Herbert Smith Freehills as deputy chair. It made various recommendations aimed at enhancing familiarity with techniques for concurrent expert evidence, including hot-tubbing, and encouraging its use in appropriate cases.

A number of the recommendations from the report were implemented in July 2017 by way of amendments to Practice Direction 35.11. The amended PD reserves the term “concurrent expert evidence” solely for hot-tubbing, in contrast to the CJC report which had used it as an umbrella term to encompass a number of other methods of giving oral expert evidence, including evidence on an issue-by-issue basis (where all parties’ experts give their evidence in relation to a particular issue, before moving on to the next issue). The PD does however expressly recognise these other methods; it provides that, to the extent evidence is not given concurrently, the court may direct it to be given in any appropriate manner, including on an issue-by-issue basis.

Note: Content up to date as at 10 June 2022

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