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The cost of switching experts

There are many reasons why a party might wish to change expert witness. For example, the litigation may have dragged on for some time and the expert may wish to be released, a fee (or other) dispute may have arisen and sometimes it becomes apparent that they are simply not up to the job.

The recent TCC decision in Coyne v Morgan and another t/a Hillfield Home Improvement provides a helpful summary of the principles that apply when a party seeks the court’s permission for such a change. Notably, it provides a timely reminder that the cost of that change may well be the disclosure of draft reports and/or other documents prepared by the first expert.

The court’s control of expert evidence

Whether expert evidence can be given at all is subject to the court’s permission, as provided by CPR 35.4(1):

“No party may call an expert or put in evidence an expert’s report without the court’s permission.”

When a party seeks the court’s permission to rely on an expert (usually at the first CMC) and that party has changed experts after embarking on the pre-action protocol procedure, the court will usually only grant permission on condition that documents containing the substance of the first expert’s opinion are disclosed. Such a condition will also usually be imposed when permission is granted to change an expert named in an order granting permission to rely on their evidence (see Beck v Ministry of Defence, Hajigerogiou v Vasiliou and Edwards-Tubb v JD Wetherspoon plc).

The condition of disclosure is imposed for a number of reasons:

  • It provides reassurance to the other side that the change in expert is not really due to the first expert’s report being favourable to it (see Brown LJ  and Lord Phillips MR in Beck v Ministry of Defence).
  • More generally, “expert shopping” is to be discouraged. Requiring disclosure of an abandoned report is a check against possible abuse (see Ward LJ in Beck v Ministry of Defence).

Notably, the condition may well extend beyond documents prepared by the expert. A very strong case of expert shopping might justify a condition that a solicitor’s attendance notes with the first expert are disclosed along with the expert’s report(s) (see Edwards-Stuart J in BMG (Mansfield) Ltd v Galliford Try Construction Ltd).

Until they are disclosed, reports prepared for the purposes of litigation are protected by privilege (Jackson v Marley Davenport Ltd). As Dyson LJ said in Hajigeorgiou v Vasiliou, in requiring disclosure of an earlier or draft report (or similar):

“… the court is not abrogating or emasculating legal professional privilege.”

Instead, requiring a party to waive privilege is, in the words of Hughes LJ (in Edwards-Tubb v JD Wetherspoon):

“… a price which must be paid for the leave of the court to rely on expert B.”

Coyne v Morgan

In Coyne, the defendant instructed an expert structural engineer (expert A) in relation to a claim regarding defective building works to a house in Solihull. Expert A met with the claimant’s proposed expert, inspected the house and produced a draft report. On review of his draft report it became apparent that, contrary to instructions, expert A had:

  • Investigated defects that were not in issue.
  • Relied on wrong information obtained from the claimant and the claimant’s expert.
  • Attempted to conduct settlement negotiations on the defendant’s behalf.

When this was pointed out to expert A, he felt that he could no longer proceed. This appeared to be a combination of expert A:

  • Considering himself to have been misled by the other side.
  • Feeling unable to exclude reference in his report to “without prejudice discussions”.
  • Believing that the defendant lacked confidence in him.

Accordingly, the defendant instructed another expert structural engineer (expert B) and sought permission at the first CMC to rely on B’s evidence.

At the CMC, the claimant contended the court should only grant permission on the condition that expert A’s draft report and other materials produced by him were disclosed. The defendant resisted disclosure on the basis that such a condition should only be imposed where a party had been “expert shopping”, which was unlike the present case.

Relevant principles

After analysing the authorities, Grant J distilled the relevant principles into five helpful paragraphs:

“(1) The court has a wide and general power to exercise its discretion whether to impose terms when granting permission to a party to adduce expert opinion evidence: that is consistent with both the general way in which CPR rule 35.4(1) is expressed and the wide and general nature of the court’s case management powers, in particular those set out in CPR rule 3.1(2)(m).

(2) In exercising that power or discretion, the court may give permission for a party to rely on a second replacement expert, but such power or discretion is usually exercised on condition that the report of the first expert is disclosed…

(3) Once the parties have engaged in a relevant pre-action protocol process, and an expert has prepared a report in the context of such process, that expert then owes a duty to the Court irrespective of his instruction by one of the parties, and accordingly there is no justification for not disclosing such a report…

(4) …the court’s power to exercise its discretion whether to impose terms… arises irrespective of the occurrence of any ‘expert shopping…

(5) The court will require strong evidence of ‘expert shopping’ before imposing a term that a party discloses other forms of document than the report of expert A…”

Accordingly, whether or not the defendant was “expert shopping” was not a prerequisite to the court exercising its power to require disclosure of expert A’s draft report as a condition of granting permission to rely on expert B.

In the circumstances, Grant J held that the court should impose disclosure as a condition of permission because expert A had already produced a draft report, discussed the expert issues in the case and attended a joint inspection with the claimant’s expert. However, this was not a “strong case of ‘expert shopping'”. On the contrary, the defendant’s solicitors had asked expert A to continue. Therefore, the defendant was not required to disclose any attendance notes, memoranda or other documents recording the substance of any conversation between expert A and the defendant’s solicitors.


Coyne v Morgan serves as a helpful and clear reminder of the dangers of changing expert after the pre-action protocol process has begun. I predict that Grant J’s useful distillation of the principles into five short paragraphs will be much cited.

For parties who are aware that the other side has switched experts, asking the court to require disclosure of the first expert’s report and/or other documents containing the substance of the expert’s opinion can be a litigation boon. Under CPR 35.11, once an expert’s report has been disclosed, any other party may use it as evidence at the trial without the need to seek the court’s permission (Gurney Consulting Engineers v Gleeds Health and Safety Ltd and Shepherd Neame Ltd v EDF Energy Networks (SPN) plc). Opinions unfavourable to the party who instructed the expert can therefore be used to full prejudicial advantage.

For those who wish, or need, to switch experts, I can see one possible loophole. Where the court has already made a more general order permitting reliance on an expert in a named field, there is no rule or clear authority that requires a party to seek the court’s permission to change experts. In those circumstances, the question of disclosure of the first expert’s report(s) does not arise at all (see Dyson LJ in Vasiliou and Hughes LJ in Edwards-Tubb). As such, tactically it might be better to wait to switch experts until after the first CMC in the hope that the court might be prepared to make a general order permitting reliance on the evidence of an expert in a named field, but without naming a particular expert. However, how a court might view such a ploy remains to be seen!

Keating Chambers Jennie Wild

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