Construction disputes can be very complex and expert evidence, for instance on the extent of extensions of time that should be given to the contractor or on the valuation of the work, can often make the difference between success and failure.
The duties of an expert in civil cases were summarised in the well-known case of National Justice Compania Naviera SA -v- Prudential Assurance Company Ltd  2 Lloyd’s Rep 68 (‘The Ikarian Reefer’) (No.1). According to Mr Justice Creswell, the duties of an expert include the following:
- Expert evidence should be the independent product of the expert uninfluenced as to form or content by the exigencies of litigation
- An expert witness should provide independent assistance to the court by providing an objective, unbiased opinion in relation to matters within their expertise
- An expert witness should never assume the role of an advocate
- An expert should not omit to consider material facts which could detract from their concluded opinion
The Civil Procedure Rules (CPR) and associated Practice Directions describe the duties of experts who are giving evidence in proceedings conducted in England and Wales and mirror those set out in The Ikarian Reefer. For instance, according to CPR 35.3, experts owe an overriding duty to the court to help it on matters within their expertise. According to paragraphs 2.2 and 2.3 of Practice Direction 35, experts should assist the court by providing objective, unbiased opinions on matters within their expertise, should not assume the role of an advocate and should consider all material facts, including those which might detract from their original opinions.
Those duties override any obligation that experts may have to the persons instructing them or by whom they are paid to provide evidence.
Although an expert should act independently, the CPR does not require that they should actually be independent of the party tendering their evidence or that they should have had no previous connection with the events relevant to the dispute. The expert can be a present or former employee of the appointing party or someone who has advised it previously. Of course, if the expert is such a person, they may be subject to greater scrutiny. If they are not able to satisfy the court that they have acted independently and objectively, their evidence will be compromised.
If the expert fails to comply with the duties described in CPR 35 they run the risk that less weight will be attached to their evidence or that the evidence of the other expert will be preferred wholesale.
In Great Eastern Hotel Ltd -v- John Laing Construction Ltd  EWHC 181 (TCC), Judge Wilcox concluded that he could attach little weight to the evidence of Laing’s expert because he had failed to consider information that had been provided by the other expert that contradicted Laing’s case. The evidence of the other expert was preferred despite the fact that he was employed by a consultant who had been involved in the project. He had approached his evidence in an independent way and was prepared to make concessions when warranted by an independent view of the evidence.
It can be difficult even for experienced experts to adhere to their duties consistently. The same quantum expert was appointed in the case of Van Oord UK Ltd -v- Allseas UK Ltd  EWHC 3074 (TCC) as in the recent case of Imperial Chemical Industries Ltd -v- Merit Merrell Technology Ltd  EWHC 1577 (TCC). In Van Oord, his evidence was described as ‘independent and clear’ and was preferred to that of his counterpart. In ICI, the situation was reversed. The court found that he had, in effect, acted as an advocate for ICI and had ignored evidence that was not helpful to its case. His evidence, therefore, lacked independence and that of the other expert was preferred.
In Robin Ellis Ltd -v- Malwright Ltd  B.L.R. 81, the court found that the expert quantity surveyor’s duty to the court had been breached because he had been instructed not to sign any agreed statement with his opposite number without the approval of his instructing solicitor.
An expert’s failure to comply with their duties can have other consequences. In Igloo Regeneration (General Partner) Ltd -v- Powell Williams Partnership  EWHC 1718 (TCC), a partial indemnity costs award was made against the claimant because the evidence provided by its expert engineer and quantity surveyor was not independent and lacked transparency. The person instructing the expert or the expert himself might also be sanctioned by their professional body. In the most serious cases, the court might hold the expert in contempt of court.
It is important that those appointing experts instruct someone who is suitably knowledgeable and who understands their duties and responsibilities. However, as the case law demonstrates, an expert’s independence is not something that should only be considered at the start of their appointment. The expert should stick to their duties throughout the process and those instructing them should help them by, for instance, making sure that they are provided with all of the relevant documentation, whether helpful to its case or not. Although it may be tempting to pressure the expert into supporting the case, the chances of success could be significantly reduced if the independence or credibility of their evidence is undermined as a result.
Expert evidence should be kept under constant review to make sure that it complies with the rules described in Part 35 of the CPR. Best practice for complying with the CPR is described in the helpful guidance published by the Civil Justice Council. It would be wise for experts and those instructing them to familiarise themselves with that document.