Following on from last week's case report, where the judgement of an expert witness was called into question by the court, we thought we would take a closer look at the role of expert witnesses.

Whether or not a doctor or other professional is in breach of a duty of care and so negligent is a question of law to be decided by the court. Given that the pursuit or defence of an action of clinical or professional negligence almost always requires an expert, why are they instructed and what is their role?

Three recent decisions serve as useful reminders of the role of experts in different circumstances.

Where no expert evidence was lead

The court in Avondale Exhibitions Limited v Arthur G Gallagher Insurance Brokers Limited [2018] WL 02464340 explained that the profession cannot be the ultimate arbiter of the applicable standard. It is for the court to decide as a matter of law what amounts to reasonable competence. It is open to a court to conclude that the standard ordinarily observed by a particular profession falls short of what is reasonably required.

The court was asked to find that insurance brokers had fallen below the standard of reasonably careful and competent insurance brokers. Avondale's insurers avoided its Commercial Combined policy following a fire. Avondale had failed to disclose two criminal convictions of its owner. Avondale argued that the brokers failed to pass on the information and failed to highlight the importance of disclosure.

The court said that the lack of expert evidence significantly limits, but does not altogether exclude, the possibility of a finding that the broker's conduct was in breach of the duty of care. The court accepted that expert evidence was not required in every case before a finding of professional negligence could be made. However as there was no evidence as to the standards within the profession of insurance brokers at the relevant times there was no basis for the court to conclude that they had been breached.

So claimants, beware: without expert evidence the chances of proving a breach of duty are very much reduced.

Where the professional concerned did not give evidence

SSE Generation Limited v Hochtief Solutions AG [2018] CSIH 26 concerned a tunnel with a design life of 75 years which collapsed after six months. In order to mount a successful defence Hochtief had to demonstrate that its engineer had exercised due skill and care. The engineer did not give evidence. In such circumstances the court was entitled to draw an inference adverse to Hochtief.

The court did not need to do so. There was evidence from other sources upon which the court could rely. There was a lack of contemporaneous criticism of the engineer's judgements. Hochtief's experts supported the decisions that had been taken by the engineer during the course of the contract. They answered the criticisms made by the other experts during the course of the trial. The judge's finding that there had been no breach of duty was upheld on appeal.

The expert evidence does not supplant factual evidence. But as breach of duty is a question of law the expert evidence was sufficient for the court to answer the question.

Nature of the expert evidence

An expert must give evidence as to the actions of a reasonably competent member of the profession. It is not enough merely to set out what they would have done. In The Bank of Ireland v Watts Group Plc [2017] T.C.L.R.7 the expert evidence was strongly criticised on a number of bases. One basis was that the expert, instead of saying what a reasonably competent monitoring surveyor would have done, set out what he would have done. This provided no assistance to the court in reaching a decision on whether, as a matter of law, the surveyors were in breach of their duty of care.

Expert evidence is central to the task the court has to carry out and its existence, absence and nature can dictate the outcome of any trial.

These three cases demonstrate that the role of an expert is to give evidence on the standards within the profession and whether or not they were met. Whereas an expert will present their evidence from the standpoint of the party that calls them, they cannot be partial and it is not their role just to tell the court what they would have done.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.