The aim of an expert witness is to put forward facts which can bear the scrutiny of cross-examination in court. The admissibility of evidence is not, in theory, something which he should be concerned with. However, it must be remembered that it is primarily from the evidence provided that an expert is able to form an opinion.
After receiving instructions from a solicitor, the expert is provided with documents including pleadings, statements, affidavits, counsel's opinion and other evidence.
The expert then interviews the client and discovers further evidence, both verbal and documentary, which is not included in exchanged pleadings or statements. This evidence may be significant but it should not be used by the expert until it is pleaded or exchanged.
An expert who refers to the new evidence using statements such as, “I am instructed that…”, or “Mr X advises me that…”, runs the risk of:
making all his instructions discoverable by the other side;
introducing evidence which calls into question the integrity of the client for not disclosing all relevant information earlier;
not being able to provide evidence supporting comments, opinions or figures in his report.
Of course, it is up to the court to decide how much weight to attach to such unpleaded – effectively hearsay – evidence which the expert introduces via a report and during testimony in court. Nevertheless, counsel for the other side will concentrate on statements of opinion, or figures in the expert's report, which are unsupported by evidence in the court, or are based on inadmissible evidence.
For example, in a recent county court personal injury case, this firm's instructing solicitor, who was acting for the plaintiff, had provided the firm with pleadings in respect of the case. In the pleadings, the plaintiff set out a claim for gratuitous care but did not quantify the number of hours of care per week given by the plaintiff's wife since the accident.
Prior to issue of our report, we contacted the provider of the care and orally ascertained the number of hours of care provided by the wife. We incorporated this into our report without expressing an opinion.
The difficulty with the case was that both the plaintiff and the provider of care were killed in another car accident before further statements could be taken. So the only evidence was hearsay and could not be incorporated into the court's pre-trial bundle of papers.
To avoid this problem, the expert should be involved in the case sooner so any discovery can be included in the pleadings. Further evidence should also be exchanged by way of supplemental statements or an exchange of documents.
Effective communication is required between the solicitor and the expert. This is particularly important when the new evidence forms a crucial part of the expert's case. The aim is to avoid a situation in which the quantum of a plaintiff's claim is reduced as a result of insufficient preparation or unavoidable events outside the control of the solicitors.