We use cookies to collect and analyse information on site performance and usage to improve and customise your experience, where applicable. View our Cookies Policy. Click Accept and continue to use our website or Manage to review and update your preferences.

False witness

01 Nov 2019 / Justice Print

False witness

The evidence of ‘expert’ witnesses who are inexperienced, inexpert, and/or easily led can lead to miscarriages of justice, as well as unwelcome notoriety.

If the duties of an expert are not carried out in the manner expected by the courts, the ramifications can be significant.

Where evidence is wholly or partially rejected, the impact on a trial can be fatal.

A notable and, unfortunately, not infrequent example of the potentially serious ramifications can be seen in a recent British case, where an expert’s failings caused the collapse of a trial involving a multi-million pound carbon-credit fraud, and the significant risk that prior trials might also be tainted.

Lack of academic qualification

The expert’s lack of academic qualification was discovered when he could not recall if he had passed any A-Levels and, in addition, admitted that he had never read a book on the subject matter of the case.

He also accepted that he had kept sensitive material obtained from the police in a cupboard under his stairs, some of which was destroyed. It was also shown that he had cut and pasted his witness statement from previous trials.

The trial judge stated that the expert was “not an expert of suitable calibre. He had little or no understanding of the duties of an expert. He had received no training and attended no courses. He has no academic qualifications. His work has never been peer-reviewed.”

Reefer madness

Experts are expected to provide evidence in order to assist the court in reaching an informed decision based on knowledge, expertise and experience.

This is a duty addressed in this jurisdiction by order 39 of the Rules of the Superior Courts, which makes it clear that the duty to assist the court overrides any duty an expert might feel is owed to a party paying their fee. This is also an obligation that experts are required to acknowledge in their reports. 

An expert should be able to stand by their evidence to such an extent that they can truthfully say the same opinion would be given, even if they were acting for the other side.

A ‘hired gun’

What they clearly shouldn’t do is act as a ‘hired gun’ with the aim of strengthening the case of the instructing principal.

This issue, however, continues to receive negative attention in court, despite various judges’ efforts to highlight experts’ obligations.

In what are colloquially known as the Ikarian Reefer principles, the duties of an expert are described as follows:

  • Evidence presented to the court should be the independent product of the expert, uninfluenced as to form or content by the exigencies of litigation.
  • Evidence should provide independent assistance to the court by way of objective, unbiased opinion with regard to matters within the expert’s expertise.
  • Evidence should state the assumptions or facts upon which the expert’s opinion is based. In addition, the expert should consider material facts that could detract from the concluded opinion.
  • Evidence should make it clear whether a particular issue falls outside of the expert’s area of expertise.
  • If the expert’s opinion is not properly researched as a result of insufficient data, then this must be stated.
  • If, after an exchange of reports, an expert has a change of view on a material matter, such change must be communicated to the other side.
  • Where expert evidence refers to photographs, plans, calculations, etc, these must be provided to the opposite party at the same time as the exchange of the reports.

The principles have been reflected in Irish judgments, most recently in the 2019 Supreme Court case of O’Leary v Mercy University Hospital Cork Ltd, where expert evidence was challenged but, ultimately, it was held that the evidence was “not sufficient to conclude … that the testimony of the expert witnesses … was affected by the exigencies of litigation”. 

Adopting the test in the Ikarian Reefer case, the court held that it had not been proved that the evidence was “anything other than independent, objective and unbiased”. 

Other cases in Britain also highlight the importance of the above guidelines, where a failure to comply with them can result in the downfall of an expert’s evidence and possibly the claim. 

In C (interim judgment on expert evidence), the court held, perhaps unsurprisingly, that the expert testimony could not be given due weight where the experts involved had not read all of the relevant papers before writing their reports. 

No independent checks

Similarly, in Van Oord UK Ltd and another v Allseas UK Ltd, an expert’s evidence was disregarded in full and deemed “entirely worthless” as there were no independent factual checks carried out, and the assertions of the expert’s principal were repeated without care.

Ultimately, the evidence was deemed to have “made a mockery of the oath”, and the expert was viewed as little more than a “mouthpiece” for the claimants. 

In addition, in the recent Libor trials in Britain, the use of one expert by the Serious Fraud Office was referred to as a “debacle”, with Lord Justice Gross remarking: “It’s not a matter to be downplayed when the Crown in a major prosecution calls a witness who is wholly out of his depth”. 

He also queried: “How did it come about that he was instructed when he lacked expertise? We are very concerned as to how he can have been instructed, the due diligence, and how it came to light.” 


Whether or not a witness is an expert will depend on their particular expertise, qualifications and experience in the area. In Bailey v Commissioner of An Garda Siochána, it was made clear that the opinions of experts are only admissible in evidence on the subject areas where they are expert.

The burden of establishing expertise rests with the party calling the witness, and must be shown before the witness gives evidence. 

It was, however, held in Martin v Quinn (1980) that a witness giving evidence about their qualifications is prima facie evidence of his or her qualification, unless rebutted.

Although an expert is dealt with under the Criminal Procedure Act 2010 as “a person who appears to the court to possess the appropriate qualifications or experience about the matter to which the witness’s evidence relates”, no such civil definition is available. 

Criminal definition

As the criminal definition is not overly prescriptive, Irish and British case law provides some guidance as to our understanding of the expertise required of an expert witness.

In ascertaining whether a witness can be considered an expert, a good starting point is the basic set of questions of Russell LCJ in R v Silverlock (1894):

  • Is he peritus [expert]? 
  • Is he skilled?
  • Has he adequate knowledge?

Other judicial pronouncements also assist. In Galvin v Murray (2001), Murphy J stated that “an expert may be defined as a person whose qualifications or expertise give an added authority to opinions or statements given or made by him within the area of expertise”.

In McFadden v Murdock (1867), it was held that expert status can be achieved through experience, such as a shopkeeper becoming an expert in the grocery business.

Further, in the case of R v Sally Clarke (2003), it was noted that evidence should not be allowed in court where the witness providing it was not adequately experienced or qualified to do so. 


The British Supreme Court found, in 2011, that there was no justification for expert-witness immunity from suit continuing, and it was abolished. As a result, experts can now be sued in contract and in tort for the evidence detailed within their reports and given in court in Britain.

In Ireland, immunity is still recognised. However, the courts continue to encourage experts to comply with their duties by alternative means.

For example, in the recent case of Waliszewski v McArthur and Company Limited, Barton J stated that the failure of the expert witness to disclose relevant material was “reprehensible and is to be deprecated”, and the court directed a copy of the judgment be forwarded to the Medical Council of Ireland. 

Law reform

Given the wide-reaching consequences that can result from unsound expert evidence, a 2016 report of the Law Reform Commission (LRC) recommended the following four duties of expert witnesses be set out in legislation:

  • An expert has an overriding duty to the court to provide independent, impartial and honest evidence,
  • An expert has a duty to state the assumptions and facts upon which their evidence is based – in addition, the expert must fully inform themselves of any fact that could detract from their evidence,
  • An expert must confine themselves to matters within their scope of expertise, and
  • An expert must act with due care, skill and diligence.

The LRC also recommended abolishing expert immunity and replacing it with civil liability, limited to circumstances in which it was established that the expert had acted with gross negligence in giving evidence or preparing a report falling far short of the standard of care expected of such an expert.

Paul Convery, Niamh McCabe and India Delaney
Paul Convery is a partner and Niamh McCabe is an associate in William Fry’s litigation and dispute resolution department. India Delaney is a UCD graduate