Expert’s impartiality called into question

Mr Justice Mostyn provides an important reminder about the impartiality of experts, referencing Lord Hamblen’s speech at the recent EWI conference.

Simon Berney-Edwards, EWI Chief Executive Officer of the EWI, said “This is once again a salutary lesson for anyone giving expert evidence. At the heart of an expert’s duties is the requirement to deliver an objective, unbiased opinion. I would recommend that anyone intending on instructing an expert witness use our Find an Expert directory where they can guarantee that experts have the necessary training in the core competencies required of an expert witness and have signed up to a code of professional conduct.”

In Gallagher v Gallagher (No.2) (Financial Remedies) [2022] EWFC 53, Mr Justice Mostyn writes the following:

The impartiality of the experts

46. In Vernon v Bosley (No 1) [1996] EWCA Civ 1310, Thorpe LJ memorably wrote:

"The area of expertise in any case may be likened to a broad street with the plaintiff walking on one pavement and the defendant walking on the opposite one. Somehow the expert must be ever mindful of the need to walk straight down the middle of the road and to resist the temptation to join the party from whom his instructions come on the pavement. It seems to me that the expert's difficulty in resisting the temptation and the blandishments is much increased if he attends the trial for days on end as a member of the litigation team. Some sort of seduction into shared attitudes, assumptions and goals seems to me almost inevitable."

47. That was 16 years ago. But the judicial remonstrations have persisted. A report in the Law Society's Gazette on 20 May 2022, entitled "Partisan experts can be fatal, Supreme Court justice warns", recorded Lord Hamblen making the following remarks, in an almost identical vein, at a legal conference:

"A Supreme Court justice today told experts that they must avoid the risk of taking sides and advocating for their instructing party. Lord Hamblen told the Expert Witness Institute that cases where experts were admonished for being partisan by the court had occurred 'far too often' in recent years – each time to the detriment of those they speak for.

[Lord] Hamblen said witnesses should refrain from becoming an advocate themselves and give evidence in such a way that you would not know which side has instructed them. 'There is nothing more fatal to the acceptability of an expert's evidence than the questions of independence and impartiality,' he said. 'It will taint all [and] it is therefore vital to avoid any hint of partiality.

'It is counsel's job to argue a case – that is not the role of an expert. If you give evidence in an argumentative manner that will undermine your independence.'"

48. While I have no concerns at all about the impartiality of Ms Longworth I have to record my clear conclusion that Mr Singleton walked on the pavement hand-in-hand with the husband. I acknowledge that Mr Singleton is a highly proficient, knowledgeable, intelligent, and articulate accountant who has fully immersed himself in the detail of the operation of Galldris. I also acknowledge that for an expert to give his or her oral evidence forthrightly in support of his written opinion is not of itself indicative of partiality. I further acknowledge that some might say that the forceful judicial demands for impartiality are tinged with unworldliness. It seems to me to be not unlikely that subconscious forces may well incline an expert, who is being handsomely paid by one of the parties, to give evidence favourable to that party. Solemn statements have been made for decades about the duty of experts to be impartial, but I have yet to see in a financial remedy case an expert, instructed and paid for by one party, give evidence adverse to that party's interests and strongly in favour of the other party's.

49. Even so, I agree with Mr Southgate QC that Mr Singleton did not deal with Ms Longworth in an open, impartial way but rather in a strategic defensive manner that has all the hallmarks of the mentality of an advocate. I agree that his attendance throughout the two-day private FDR is highly suggestive of de facto membership of the husband's team. He also wrote an email on 26 September 2021 to Mr Kerins about a possible comparable transaction stating "it is a great comparable and we can argue that the contracts it has are longer term and more secure than those within Galldris" (my emphasis). This laid bare his perceived membership of the husband's team. His written evidence put forward figures for A and B which were as low as he could tenably go without falling off the spectrum altogether. They were not impartial figures.

50. The evidence of the experts was hot-tubbed and I allowed them politely to interrupt each other. Mr Singleton's interruptions were forthright, abrasive and adversarial, even degenerating on one occasion to him rebuking the court for allowing Ms Longworth to descend, in his opinion, to excessive detail.

51. I therefore do regard Mr Singleton as parti pris. However, as indicated above, I am satisfied that he has accurately recorded the nature and respective functions of Tier-1 and Tier-2 contractors and has accurately recorded the reasons why Galldris has made the decision to transition to Tier-1. Had he been more impartial I believe that he would have insisted on forecasts for 2023 and subsequent years being produced. However, the absence of those forecasts is not to be laid at his door.

52. Even absent my conclusions about his partiality, I would not have accepted his figures for A and B. But I agree with Lord Hamblen that his partiality deals a fatal blow to his use of those figures.