Case law analysis: The independence of experts

Expert witnesses play an important role in legal proceedings by sharing their expert knowledge of a particular specialist field. In doing so they help the tribunal interpret the factual evidence it has heard and understand all of its implications.

This process of sharing knowledge is achieved by the expert giving evidence of their opinion upon a particular point, based upon their review of the relevant facts. Almost invariably the expert witness will receive payment for the services they provide in giving their opinion.

Witness's duty

All witnesses have a duty to tell the truth, whether they are giving evidence of fact or of opinion. However, because of the particular reliance the tribunal may place upon the opinion of an expert witness, and because of the risk that some experts may favour (consciously or subconsciously) the position adopted by their client, a body of rules and legal principles have developed that regulate the manner in which experts conduct themselves.

The most important principles are found in the Civil Procedure Rules (or CPR), being the rules that apply to the conduct of court proceedings. These very clearly state that it is the duty of the expert to help the court in relation to matters within their expertise and that this duty to the court overrides any obligation to the person from whom they have received instructions or by whom they are paid.

The other well established principles are that:

The evidence should be, and should be seen to be, independent, and not influenced by the pressures of litigation. In other words, the expert should not be concerned by whether their evidence favours the case of one party or the other.

That the role of the expert is to provide independent assistance to the court by way of an objective unbiased opinion, and never assume the role of advocate. In other words, the expert must not take sides, it being for the solicitors and/or counsel to present their opinion in the context of the case.

The facts and assumptions upon which the opinion is based should be identified, and all material facts should be considered, even where they would detract from the opinion. In other words, the expert cannot pick and choose only those facts that support their opinion, but must consider all material facts.

Where a particular issue falls outside the expert's expertise they should say so. In other words, the expert should resist the temptation to be helpful and offer an opinion in an area in which they do not have real expertise.

If there is insufficient factual data such that the opinion is provisional that should be clearly stated. In other words, if the expert does not feel fully comfortable with the opinion reached, they should say so.

If the expert changes their opinion after reports have been exchanged, that should be communicated to the other party as soon as possible. In other words, if an expert realises they are wrong, they should say so.

Where the expert relies upon documents, calculations and the like, these should be provided at the same time as the report. In other words, the expert must be open as to the way in which they have reached their opinion, so that it may be understood and challenged.

These same principles apply whether the tribunal is a court or arbitration.

If the expert does not apply these principles they run the risk of the tribunal either giving their evidence very little weight or, possibly disregarding it altogether.

Reputation at risk

The recent case of London Fire and Emergency Planning Authority (LFEPA) -v- Halcrow Gilbert Associates Ltd and Others illustrates the consequences for experts and their clients when this occurs. The dispute concerned an allegation of professional negligence because of a fire that occurred in a building specifically designed to train fire fighters how to put out fires. Unfortunately, the fire in question was not lit for training purposes but a real fire that was not meant to have happened. LFEPA alleged that the fire was a result of Halcrow's negligence and relied extensively upon four experts. In respect of three of these experts the judge was severely critical, saying the evidence of one was "partial, biased, and on occasions misleading to such an extent that it could not be described as independent", observing that another reached a "conclusion that was wholly unsustainable" and stating that a third gave rise to concern as to his "lack of independence as an expert". The weight attached to what each of these experts had to say was reduced accordingly, and to the extent that LFEPA's case relied upon those experts it was undermined as a consequence.

The reasons for these damning comments were varied, but one point that was specifically commented upon was the involvement of one of the experts in a dual capacity to both devise and implement a scheme of remedial works (for which a fee would have been paid as a normal consultant, rather than as an expert) and then to give independent evidence upon the appropriateness of that remedial scheme. The potential for conflict is apparent.

The message for experts is clear, that if they do not wish to have their professional reputation shot to pieces in court they must always remember that their duty is first and foremost to the court, and they must not allow anything to undermine their independence and professional credibility.