At a principled level, the decision suggests that a defendant does not have an unqualified right to instruct an expert of its own choosing for the purposes of advancing its defence alone. Relevant context to this is that the touchstone of the expert framework in English proceedings is independence, and the expert's duty to the Tribunal is paramount (and overrides any duty to the party instructing the expert).
In some respects, the decision may be viewed as a welcome development for Claimants as it suggests that the Defendant's approach to the analysis of the economic data may be hamstrung (to some extent) by what the Claimant's expert proposes to do. In the instant case, the Claimants' intention to not distinguish between the activities of the Defendant groups was one of the (key) reasons why the Tribunal ordered the Defendants to instruct a single joint expert. From a defendant's perspective, in practical terms, the decision raises a number of concerns:
- In circumstances where the single joint expert does not share the views of the expert the Defendant had intended to appoint, the defendant may effectively be precluded from advancing the economic analysis its preferred expert had proposed to adduce.
- There may be a "practical" conflict between the Defendants, particularly if the relevant deadlines are tight, as each defendant will want the single joint expert to focus on its part of the case.
The decision also suggests that in seeking their own individual experts, defendants might not want to rely on the fact that a defendant-specific assessment is required in order to account for differences in datasets (for example, certain control variables may be unique to a specific defendant). As the Tribunal noted, whether separate models are required in order to account for the differences in the datasets is a matter for the experts, however this does not mean that each defendant should have its own expert. While, at present, the Tribunal did not consider there to be any relevant conflicts as between the defendants, as and when the time comes to conduct the modelling, it is not difficult to envisage a situation where conflicts do emerge, not least because certain modelling choices applied to any consolidated dataset may have different impacts for different defendants - some modelling choices may benefit some defendants while others may put them at a (relative) disadvantage. It is clear that the Tribunal intends to take things in stages and to keep the issue of potential conflicts under review, including, once the Defendants are in receipt of the Claimants' expert report.
On the issue of proportionality, perhaps surprisingly, the Tribunal were not able to form a view as to the relative costs of employing one single joint expert instead of three separate experts – although there will only be one report, it will still need to be reviewed by three different solicitor and counsel teams. Depending on the point at which the Tribunal orders the use of a single joint expert, it may result in a delay to the trial date as the new jointly instructed expert will need sufficient time in order to familiarise themselves with multiple datasets, most likely with the assistance of the existing expert advisers (adding time and costs). The existing expert advisers may also need to remain involved in the proceedings for the purposes of assisting with any specific disclosure applications, as they are likely to have a better understanding of the relevant data, at least during the period while the single joint expert "gets up to speed".
Overall, the decision reflects the Tribunal's increasing concern about the scale of proceedings in the context of multi-party litigation, in particular, the implications this has for the expert process and how this can best be managed (in light of what the Tribunal has learned from previous cases). It is clear that the Tribunal is keen to avoid a situation where the parties' respective experts are "ships in the night". This is an issue which the Tribunal has been conscious of for many years, and has often taken active steps to avoid.[2] However, it is not clear that appointing a single joint expert is the best tool for managing this risk. For example, it would have been open to the Tribunal to receive submissions from the parties regarding their proposed methodologies for the purposes of considering whether a non-defendant specific analysis reflects the "optimal" approach, and the relative advantages/disadvantages associated with a defendant-specific analysis. This type of exercise has been conducted in other cases, and it is possible that in this case it might have helped flush out, at an early stage, the areas of dispute between the experts insofar as they relate to the crucial building blocks of the expert analysis.[3] Certainly it is an option which defendants will in other cases be considering keenly in light of this judgment.
The existence of three separate experts for each of the Defendant groups would not have necessarily meant that one of those experts would not have (or could not have) considered the evidence in its totality (as each of the Defendant group's experts would have access to the other Defendant groups' data) – to some extent, each of the Defendant group's experts would have needed to consider the totality of the evidence in order to respond to the Claimants' report.
Finally, while the Tribunal intend to keep the issue of conflicts under review, to the extent these are identified later down the line, including following the receipt of the Claimants' expert report (and the instruction of a single joint expert), the need to deal with those conflicts may significantly prejudice any trial timetable, and generate further costs.
We understand that certain of the parties may have sought permission to appeal from the Court of Appeal.