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| 4 minutes read

The role of expert advisors and the perils of expert shopping

A recent case before the Technology and Construction Court serves as a useful reminder of the powers of the court and potential consequences when a party swaps experts to a litigation.

In this case, the condition imposed by the court in allowing the Defendant to change its expert was the disclosure of an attendance note in which the Defendant’s previous expert had expressed his views on causation. This condition was imposed even though the Defendant claimed that the initial expert was engaged in an advisory capacity and the engagement had preceded significantly the commencement of the pre-action protocol process.


Matthew Rogerson (t/a Cottesmore Hotel, Golf and Country Club) v Eco Top Heat & Power Ltd concerned a fire at a hotel and country club. The owner of the hotel (the Claimant) claimed that the fire was caused by a firm of building contractors (the Defendant) that had been carrying out window installation works at the hotel at the time of the fire. Expert evidence was required on the potential cause of the fire, which the Claimant said was down to a cigarette discarded by one of the Defendant’s employees.

Following the fire, the Defendant appointed an expert who had attended site visits, met with the Claimant’s expert and been involved in the interviewing of witnesses. 16 months later, the Claimant issued a letter before action in relation to the dispute. The Defendant’s response did not identify that it had instructed any expert. Subsequently proceedings were issued and at the CMC it became clear that the Defendant intended to call a different expert to the one that had originally been involved.


Expert shopping is the practice where a party to litigation seeks to replace its expert with somebody else to provide an opinion on the same matters or areas of expertise. Although there are some legitimate reasons for changing an expert (such as illness or availability) the general presumption with expert shopping is that this is done when the first expert gives an opinion that is contrary or incompatible with the party’s case. The courts therefore strongly discourage the practice of expert shopping. This is done through the procedure of CPR 35.4, which requires the court’s permission for any party to call an expert and to which conditions can be attached.  Where courts believe that expert shopping has taken place, these conditions can include requiring the disclosure of the previous expert’s report. In some cases, the court’s powers can extend to requiring earlier versions or drafts of reports to be disclosed, as well as waiving privilege in certain expert communications.

However, these conditions are normally only imposed when the swapped-out expert was instructed in the context of live or prospective litigation (including experts involved during the pre-action protocol stage). The practice of expert shopping (and the court's response to this) does not apply to privately engaged expert advisors that are instructed to provide an early assessment of the merits of a party's position to guide its strategy.

The questions before the court in this case included how far back in time the court’s jurisdiction to require disclosure of earlier expert materials went, given that the initial expert’s involvement in this case appeared to have ended some time before the formal pre-action process had commenced.

Defendant’s arguments

The Defendant argued against any disclosures being made in relation to its initial expert. The Defendant’s arguments included:

  • There was a clear distinction between an expert instructed in the immediate aftermath of an event, such as a fire, for the purposes of taking private pre-protocol advice and one instructed once litigation is in prospect and the potential issues are known about. 
  • The initial expert had not produced any written report to the Defendant and had only provided a view on causation in a privileged discussion with solicitors, recorded in an attendance note.


The Court found that despite the initial expert’s early involvement in the case, the scope of the expert’s instructions went well beyond that of an expert advisor employed to provide a private assessment of the case.

  • The level of engagement and work that the initial expert had undertaken was considerable, including joint inspections with the Claimant’s expert, discussions with the Claimant’s expert on causation and meetings with witnesses.
  • By the time of the initial expert’s involvement, it was already clear that litigation would occur and that the parties had locked horns over the issue of the cause of the fire, to which the expert evidence related.
  • Although no written report had been produced, this could have been because there had been careful “curation” of evidence to ensure that the expert views were only expressed in privileged conversations.
  • The Defendant had not disclosed the engagement terms for the initial expert, even though this evidence would have been easy to provide. If the Defendant wanted any distinction to be drawn in relation to the purpose the expert had been engaged for, it was for the Defendant to disclose the retainer to evidence this.

The court drew the inference that expert shopping had taken place. In the absence of any report, the court therefore imposed the condition that privilege was waived in the attendance note where the initial expert’s views on causation had been expressed.

Learning points

This case highlights the importance of clearly scoping, drafting and then actively managing the instructions of any expert advisor used pre-action when proceedings are anticipated, particularly in cases where there is a chance that this same expert will not be used as the CPR 35 expert for the litigation.

For parties that do decide to use a different expert for the litigation than any expert advisor instructed previously, the written instructions to the expert will serve as important evidential material to counter any inferences that expert shopping has taken place.

If, as the Defendant now seeks to suggest, I should draw a real distinction between an expert merely instructed for an initial inspection and report on the one hand and an expert instructed for the purposes of prospective litigation on the other, it behoves it to disclose the retainer to show it was the former and not the latter.