Not in this town: The days of the “hired gun” are over

The Irish Court of Appeal has voiced strong criticism of the “hired gun” expert who takes on the role of advocate, and has signalled much tighter control and greater enforcement of the rules relating to expert evidence (Duffy v McGee Insulation Services). The Court also warned that lawyers who call experts who do not comply with their duties to the Court may face adverse consequences in respect of legal costs.

The role of the expert

The role of the expert is to assist the Court as to matters within their own field of expertise. Crucially, the expert’s duty is to the Court, not to the party who retained them. Expert evidence must be objective, impartial and independent. This requires experts to remain open to alternative possibilities and, if necessary, show a willingness to change their mind when confronted with new information.

In Ireland, experts are required to acknowledge this duty in any report prepared by them. They are also obliged to disclose any financial or economic interest in any business or economic activity of the party retaining them.

However, the Irish Court of Appeal this week expressed serious concern that many experts do not understand their duties or take them seriously. In his judgment, Judge Maurice Collins (then on the Court of Appeal, but since appointed to Ireland’s highest court, the Supreme Court) noted that some experts wrongly regard themselves as advocates for the cause of the party who instructed them. This, he said, is “unacceptable” and needs to change.

Judge Noonan, who delivered the main judgment of the Court, noted that while the courts have strived to avoid “the hired gun syndrome”, more may need to be done by way of augmented rules of court.

“Advocate” expert evidence not admissible

The Court of Appeal stated that an expert who assumes the role of an advocate, and does not give objective, impartial and independent evidence, is not qualified to be an expert and their evidence should be excluded.

With regard to the appeal before the Court, Judge Noonan found that the expert whose evidence was at issue had “impermissibly donned the mantle of a partisan advocate in his efforts to discredit the claim of the plaintiffs.” The Court identified a number of aspects of his evidence that gave rise to serious concern, including that the expert had purported to give an opinion on the legal principle of res ipsa loquitor and also purported to give a medical opinion on the plaintiff’s psychiatric and skin complaints, both areas being entirely beyond his competence. In so finding, the Court upheld the trial judge’s decision to exclude the expert’s evidence in its entirety, stating that there was an “abject failure” to comply with the most basic obligation of an expert, namely, to be objective and impartial.

Words of warning for lawyers instructing experts

Judge Collins emphasised the responsibilities of the lawyers instructing experts, noting that they must ensure that:

  • the evidence is relevant and likely to assist the Court;
  • the expert has the necessary expertise to give the evidence;
  • the expert confines their evidence to issues properly within their area of expertise; and
  • critically, the expert fully understands these requirements and is in a position to comply with the duties of an expert witness.

Judge Collins warned that lawyers who fail to adhere to these requirements run the risk of adverse cost orders.


This is a further reminder, building on the decision in McKillen v Tynan, of the Irish judiciary’s much greater enforcement and policing of the rules regarding the quality and reliability of expert evidence. 

Parties instructing experts should ensure that the experts fully understand their role and that their overriding duty is to the Court. Failure to do this may mean that the expert evidence will not be admitted and that there may be adverse cost orders, including potentially against the lawyers themselves in the form of wasted cost orders.

The decision is a reminder that the appointment of an expert and whether their evidence should be relied up requires very careful consideration.