Mr Alexander Nissen QC (Sitting as a Deputy High Court Judge) applying British Airways had to decide whether it was necessary to call expert evidence. There was some dispute as to whether the cases governing the calling of expert evidence in professional negligence cases were to be applied. The judge said that they did not apply. He said,

26 … This is not a solicitors’ negligence case. It is a claim against a firm of quantity surveyors. It is true that the Claimants allege that the Defendant held itself out as at least as competent as lawyers but that allegation is pursued in the alternative and may not be proven on the facts. In those circumstances, it will be necessary to judge the Defendant solely by the standard of a reasonably competent quantity surveyor providing dispute resolution services.

In respect of its defence to the holding out case, the Defendant does not seek to adduce expert evidence to demonstrate what a reasonably competent solicitor would have done in the circumstances. Had it done so, the question would have arisen as to whether it was necessary to adduce expert evidence and whether the contentions were matters of law or matters of practice.

It seems to me that, unlike Bown , they would be largely, if not wholly, matters of practice. However, the Technology and Construction Court is a specialist Court. All its Judges have had considerable experience of dealing with construction disputes and, particularly, arbitrations relating to such disputes. I am quite sure that any Judge trying this case would not need any expert evidence to explain what a lawyer in a construction dispute should do or say. But, for the reasons I have given, that point does not arise.

27 On the facts of this case, I can see that there may be instances where there may be differences between what a legal practitioner would do or say in a given situation and what a quantity surveyor might do or say. It will suffice to give three examples. In doing so, I make clear that I am making no finding that there is in fact a difference. I am merely identifying examples of situations in which I can see that there may be a difference.

The first relates to ATE insurance. The Claimants complain that the Defendant should have alerted them to the existence of ATE insurance or other funding options. It may be that a reasonably competent quantity surveyor engaged in dispute resolution would be less well versed in that type of funding than would be a solicitor.

The second example relates to the allegation that the Defendant should have obtained legal advice. By definition, this is not something which a solicitor would have needed to consider.

The third example relates to the provision of advice on the merits. When advising on the merits of a final account claim, it may be (depending on the facts) that a quantity surveyor is fulfilling a different function from a lawyer. When advising on the merits, a solicitor will rely on the expert evidence which he has obtained from a quantity surveyor. The solicitor must then take into account his own views on the likelihood of that evidence being accepted from a forensic perspective. On the other hand, the quantity surveyor will be focussed on the valuation aspect of the case. As regards the valuation disputes, he will have a greater understanding of the underlying valuation issues than would a solicitor yet he may be less well placed to provide an independent view on the likelihood of that evidence being accepted from a forensic perspective. It all depends on what he is asked to do.

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.

Edited for ease of reading. See the other posts under this tag.