Stay in your lane! How expert witnesses can stray away from their duty to the Court
The judgment in 125 OBS Nominees (1) and anr v Lend Lease Construction (Europe) and anr  provided useful judicial clarification as to when expert evidence from certain disciplines will and will not be appropriate and how experts can walk a fine line between advocating their client's case and providing independent evidence.
In an earlier blog we discussed how this case reiterated the Court's reluctance to go behind commercial settlement agreements when a party seeks to recover them from a paying party. The Defendants' quantum expert spent time addressing the settlements in his evidence but, as the Judge noted, he also "did not propose or put forward figures that would have been a reasonable range for any of the settlements. This was at least in part because he was not qualified to give expert evidence on the reasonableness or otherwise of any of the settlements." The Defendants' quantum expert also sought to criticise the cost of legal advice obtained to settle claims. He considered that the "Claimants should not have paid more than £5,000 in lawyers’ fees per settlement." The Judge held that the quantum expert was "not qualified to express that opinion" and reached his own view on the matter, without expert input.
Similarly, when it came to the evidence of the liability experts the Judge gave greater credence to the views of the Claimants' expert, who had extensive first-hand experience in the field. Conversely, the technical expert called on behalf of the Defendants notably lacked experience in areas on which he sought to opine and relied on extracts from various published papers to attempt to make out his arguments. Crucially, the Defendants' expert had also failed to impartially assess the implications of fabricated documents that had been provided by his client's supply chain. The Judge commented: "I do not understand how the Defendants could maintain to trial the assertion that the documentation from the supply chain proved that the glass… had been heat-soaked when they should have appreciated that it showed no such thing".
The Judge remarked that it was quite unclear how the Defendants' expert "could, consistently with his duties to the Court, have failed to make plain his clear understanding that some of the documentation was fabricated and that, whatever else it showed, the documentation as a whole (on which he commented extensively) did not support his client's case". The judgement records that by 9 November 2016 at the latest, the Defendants' expert had been told by the lawyers that the documents were false. The Judge considered that the fact that the supply chain had provided fabricated documents was sufficient to at least "raise doubts" over other unverified documents. In such circumstances it was impossible to assume, based on the lack of clear and reliable evidence that the supplier had heat soaked the glass properly. Yet the Defendants' expert "clung to the assumption" and the Judge found that "it was neither expert nor rational for him to do so".
In another recent decision in which RPC acted for the Defendant (The Governors and Company of Bank of Ireland and ors v Watts Group PLC ) the bank's expert's independence was questioned in even closer terms. The expert for Claimant was found to have "lacked realism", have been unreasonably intransigent and had attempted to mislead the court by the selective quotation from RICS guidance. The Judge in that case commented that he had never before "seen a Joint Statement between experts that contained no agreement at all", for which the judge held the Bank's expert responsible.These recent cases highlight the importance of expert witnesses remaining within the confines of their expertise and providing independent views to the Court. Experts owe their duties to the Court rather than those paying their bills and the Court will not be assisted by experts advocating their client's case, particularly where the arguments are patently deficient.