Expert Witnesses ' Court Of Appeal Calls For Culture Change

Published date10 November 2022
Subject MatterLitigation, Mediation & Arbitration, Trials & Appeals & Compensation
AuthorMr Donal Twomey and Sharon Burke


The recent Court of Appeal decision in Patrick Duffy -v- Brendan McGee1 has again highlighted the duties and responsibilities of expert witnesses. The judgment of Collins J noted that, far too often, expert witnesses appear to fundamentally misunderstand their role and wrongly regard themselves as advocates for the cause of the party by whom they have been retained. Such a culture is unacceptable and needs to change. To that end, the judgment emphasised the need for the courts to be forceful in policing the rules and in taking appropriate measures where those rules are not complied with.

It outlined that where a significant departure from the essential requirements of objectivity, impartiality and independence occurs, it must be taken very seriously. The Court concluded that where an expert fails to discharge their duty, it will go to the admissibility of expert evidence, rather than merely to the weight to be given to such evidence.

In this case, the Court found that an expert witness called by the defendant in the field of toxicology had "seriously abused his position as expert witness", and "demonstrated a total lack of understanding of, or respect for, the duties of an expert witness in this jurisdiction". The Court made a number of observations about the toxicologist's written report, noting that it contained numerous "red-flags" indicating the approach he was likely to take in his oral evidence such as:

  1. Expressed views on legal doctrines;
  2. Categorical statements about disputed issues of fact about which he had no independent knowledge;
  3. Accusations against the Plaintiffs of "misrepresentations";
  4. Identification of alleged contradictions in the Plaintiffs' accounts;
  5. Suggestions that the Plaintiffs' treating doctor had been misled by the information provided to him into making "false exposure assumptions";
  6. Commenting on views set out in psychiatric reports;
  7. Expressing his views on medical reports prepared by the Plaintiffs' family doctor.

Remarking on the oral evidence that the toxicologist had given in the High Court case, the Court found that the toxicologist had seriously abused his position as expert witness to repeatedly accuse the Plaintiffs of outright dishonesty and deception, in circumstances where he had no independent knowledge of the facts and no role whatever in resolving any conflicts of fact between the parties. It noted that his evidence clearly indicated that he "was acting as partisan advocate, clinging at all costs to an...

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