In the case of  BDW Trading Limited v Lantoom Limited [2023] EWHC 183 (TCC), one of the experts was heavily criticised. The criticisms are worded perfectly so that we simply reproduce an excerpt from MRS JUSTICE JEFFORD DBE's judgment - it really highlights the most common pitfalls for experts.

"24.  Firstly, Mr Choat submitted that there were patent breaches of the CPR. That submission was well-founded. The Report did not set out the substance of Mr Hunt’s instructions as it should have done pursuant to CPR Part 35.10(3). He said in cross-examination that he thought he had covered this in the Introduction to his report but, as I read it, the Introduction comprised firstly a brief statement that he had carried out extensive investigations into the issues arising, during which it had become clear to him that BDW’s allegations were misguided, and then an explanation of the structure of his report. The report did not summarise the range of opinion on issues (contrary to paragraph 3.2(5)) of the Practice Direction, even where Mr Hunt’s opinion was a minority one.

That a report is lengthy is not necessarily a criticism but in this case it made it particularly challenging for the claimant and the court to navigate and to digest the substance of Mr Hunt’s opinions and, in the case of BDW’s experts, respond to these. This was unhelpful to say the least but more importantly it made it difficult to relate his opinions to the issues in the case and, on a number of occasions, they ranged outside the pleaded issues.

It emerged at trial that Mr Hunt had taken a particular and unusual approach to his task. As he said in his report, as an expert for the defendant, he saw his role as testing the evidence presented by the claimant “assuming the claimant had undertaken a rigorous investigation in the first instance”. In his view, in this case, the claimant had not and only “minimal tangible evidence” had been presented by the claimant and its experts. Although that approach reflects the burden of proof on BDW, it does not reflect the duty of an expert to the court - the defendant’s expert should not only test the claimant’s evidence but should weigh all of the available evidence. It was perhaps this approach that led to some notable omissions from the Reports. I address below the report prepared by Petrolab and disclosed by Lantoom and the tests carried out for Lantoom by two firms, RSK and ACS. Mr Hunt only referred to the Petrolab report in his Rebuttal Report and did not refer to the tests at all even though they were relied on and discussed in BDW’s expert evidence. Ms Jones sought to explain this omission on the basis that Mr Hunt had focussed on what he considered relevant and that he did not consider these tests important to assessing the cause of failure. Thus is seems that Mr Hunt’s approach to testing the evidence of the claimant was not to refer to it all if he did not think it relevant.

Further, this approach to testing the claimant’s evidence seems to me to have led Mr Hunt into believing that it was sufficient for him to raise numerous possibilities as to causes of the issues experienced on this development without any evidential basis for a positive case. Mr Hunt then claimed that his own investigations had been undertaken in “difficult and restrictive circumstances” and that he had been hampered by the defendant’s limited resources. There was no evidence that Mr Hunt had been acting in difficult and restrictive circumstances. The particular example that he appeared to give was that he had been denied access to or had difficulty accessing the Site. BDW provided as part of a Chronology a list of 10 visits to Site, between October 2018 and August 2019, by either Mr Hunt or Enigma, his then instructing solicitors, who collected samples on Site on his behalf. Apart from one occasion when the visit was at short notice, there was no complaint in any correspondence about any difficulties with access. The defendant’s updated costs budget in April 2021 gave a total of nearly £1.3 million for experts. Neither of Mr Hunt’s excuses was well-founded.

Mr Hunt also expressed himself both in writing and in the witness box in trenchant language. Ms Jones submitted that, where he held strong views, it would have been wrong of him not to express himself firmly and that nothing he had said was offensive or involved accusations that threatened the careers of others. That is not the point. The point, to my mind, was that Mr Hunt repeatedly gave the impression that he knew better than everyone else – even when his position was a minority view or against the weight of the evidence. The lack of reflection and consideration of the weight of contrary evidence gave me no confidence in Mr Hunt however forcefully he expressed himself. When he was challenged on some of these views, his answers in cross-examination were prolix and rambling, bordering on incomprehensible, despite Mr Choat’s best efforts to disentangle the answers. Reinforcing the view I have already expressed about Mr Hunt’s evidence, it seemed to me that his approach was that the issues he was being asked about were so complex that only he understood them properly and that it was too difficult for him to give a simple answer to the court. In consequence he did not give a simple or coherent answer and did nothing to build my confidence in his evidence."