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‘Hired gun syndrome’ a risk with expert witnesses, judges warn

New law and rules may be needed to combat ‘unacceptable’ litigation culture which can benefit wealthy, says Court of Appeal

The Court of Appeal (COA) has warned expert witnesses and lawyers there needs to be a “significant change” in an “unacceptable” litigation culture concerning the use of expert evidence.

The three-judge COA voiced particular concern that it is “commonplace” for experts to see themselves as advocates for the party who retains them and about the “excessive and expensive” use of expert evidence potentially benefitting wealthier litigants at the expense of the less well-off.

Mr Justice Seamus Noonan said some of the most high-profile miscarriage of justice cases arose from “serious failures” of experts and it is therefore right, as set out in many judgments and rules of court, the law expects and demands the “highest standards” of them.

The expert’s duty is “to assist” the court, to provide an objective opinion and ascertain all relevant facts, whether they support the client’s case or not. The court is not obliged to accept the evidence of any particular expert, even when uncontradicted.


It is “unfortunately commonplace for experts to succumb to the natural tendency to put the interest of their own clients first, consciously or otherwise”, he said. The “hired gun syndrome” is “unfortunately one with which all lawyers are familiar” and perhaps an inevitable byproduct of adversarial litigation which the courts have strived to avoid by developing principles to be applied when considering the duties of experts.

“Perhaps more needs to be done by augmenting the rules of court,” he said.

There is nothing to prevent litigants “with deep pockets” consulting any number of experts until one is found who will support the case being made with no obligation to disclose such information to an opponent, he noted.

Mr Justice Maurice Collins said it was “unfortunate” that recommendations of the Law Reform Commission in 2017 for legislation on the treatment of expert evidence have not been implemented.

There appears to be “no reason” why many of the recommendations, which address duties of experts, could not be implemented by amending existing court rules or issuing practice directions, he said.

The most significant concern about expert evidence relates to issues of objectivity, impartiality (lack of bias) and independence, he said.

Lawyers acting for parties adducing expert evidence have a “critical” duty to ensure the expert witness fully understands their duty and can comply with it.

Courts need to be “forceful” in policing the rules and taking appropriate measures where those rules are not complied with, including excluding the expert evidence, he said.

Novel scientific evidence

Assessing the reliability of expert evidence presents “significant” challenges, he said, with a “real risk”, particularly in the area of complex expert evidence based on novel scientific theories or methodologies, the court may inadvertently admit and rely on unreliable evidence.

The Irish courts have not set a test requiring expert evidence to achieve a specific threshold of reliability before it can be admitted but have sometimes refused to admit novel scientific evidence because its reliability had not been sufficiently established and, in some cases, referred to a requirement for expert peer approval.

Mr Justice Donald Binchy agreed with both judgments, delivered this week when the COA dismissed an appeal against a judgment in favour of a couple, Patrick and Anita Duffy. They were awarded some €2 million damages after the High Court found they suffered injuries as a result of exposure to toxic chemicals present in their home at Annagry, Co Donegal, during and after the installation of spray foam installation on February 18th, 2016. The damages were awarded against the insulation installer, Brendan McGee, trading as McGee Insulation Services, Largenreach, Downings, Co Donegal.

The COA upheld as “perfectly correct” the High Court decision to exclude all of the evidence presented by a US-based expert called by the defence.

Mr Justice Noonan said the witness had “impermissibly donned the mantle of a partisan advocate” in his efforts to discredit the claims of the plaintiffs and failed to comply with the most basic obligation of an expert, to be objective and impartial.

“This is a disturbing case and it is certainly to be hoped that its like will not be seen again,” said Mr Justice Collins.

Mary Carolan

Mary Carolan

Mary Carolan is the Legal Affairs Correspondent of the Irish Times