Mr Alexander Nissen QC (Sitting as a Deputy High Court Judge), applying British Airways, said,

28. In all the circumstances, I conclude that expert evidence is necessary. This is a case of professional negligence where evidence from someone in the same professional field is required. But, in any event, there are issues in respect of which the evidence would be of assistance and it is reasonable to require expert evidence to be given in the context of the proceedings as a whole.

29. Nonetheless, I agree with the Claimants’ submission that this evidence should be confined to that which is strictly required.

30. I have therefore come to the clear conclusion that the appropriate course is to allow expert evidence on condition that it is subject to close control. I am mindful of the Court’s significant experience of dispute resolution in the construction sphere and in respect of which it will not require any assistance. I am also concerned that, if unrestrained, there is a real risk that experts will provide swathes of commentary on each communication passing between the parties, giving their own slant or interpretation of what happened and what ought or ought not to have been advised…That must not happen in this case. If evidence of that sort is provided, the Court will be able to make adverse orders for costs, even on an indemnity basis, against the party seeking to rely on such evidence.

31. The course I have decided to adopt is to require the Defendant to provide a list of issues by reference to the pleadings which identifies the specific points on which it intends to provide expert evidence and what the relevant question for the expert should be. The focus should obviously be on those points where the standard or duty is said to be different to that which would be applicable to a lawyer engaged in the business of construction disputes since the latter is a matter about which the Court will be familiar. The Claimants will have an opportunity to respond to the list. Thereafter, the parties should endeavour to agree a list. If there remains a disagreement about the scope of expert evidence to be obtained in light of these exchanges then the matter can be referred to the Court for determination on paper. Once the list has been finalised, it will provide an agenda on which the experts can report.

32. Mr McNae suggested that a list of issues of the type described would serve as the basis for instruction of a single joint expert. In my view, this is not an appropriate case for a single joint expert. This is a claim of significant value and is one in which both parties should have an opportunity to call their own evidence. Whilst both parties accepted that expert evidence would be secondary to the findings of fact, that feature does not mean it will be wholly peripheral. In respect of a given issue it is possible that the evidence could be determinative.

British Airways is cited separately under this tag. Highlighting added for ease of reading.