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Expert witnesses’ duty is to court, not parties paying them – judge
Michael Peart, former judge of the Court of Appeal Pic: Jason Clarke

25 Feb 2021 / justice Print

Expert witnesses’ duty is to court, not paying parties

The “uncomfortable question” of why so many expert witnesses only ever appear either on the plaintiff side, or on the defendant side, was raised this morning (25 February) by Mr Justice Michael Peart, formerly of the Court of Appeal.

“Very often the names that appear on  a plaintiff side, never appear on a defendant’s side, and vice versa,” Mr Justice Peart said, questioning whether this is an indication of bias, conscious or unconscious.

“Those are uncomfortable questions,” he said, because the whole purpose and primary duty of an expert is to be objective and independent of the parties.

“In addition, their primary duty is to the court and not to the parties that are paying them,” he said, speaking at an online conference on expert witnesses, organised by La Touche Training, which trains non-lawyers on legal matters.

Increase in litigation

Mr Justice Peart, who is a former solicitor, said that the expert witness has become an indispensable part of much of the increasing amount of litigation that comes before the Irish courts.

It’s not unexpected that judges will need specialist assistance, given the volume of litigation, he said, and this has led to a “cottage industry” in expert advice-giving.

DNA experts, mobile phones experts and blood-spatter experts all regularly appear at both civil and criminal courts, he said.

“The question of what constitutes an expert is one that exercises judges’ minds, because not everyone can be regarded as an expert, even though they might be experienced in the area of work,” he said.

Telling the truth

Judges must assess the weight to attach to sets of evidence, he added, describing as “remarkable” how the same names pop up as experts in numerous personal injury cases. 

Barrister Mark Tottenham echoed the judge’s sentiments when he described an expert witness’s primary duty as that of telling the truth.

The expert witness must also :

  • Report, in oral evidence,
  • Be independent of the client and legal team,
  • Give evidence within their own expertise to assist the court in reaching its own decision,
  • Research or ascertain the relevant facts, to educate the court in specialist or technical knowledge,
  • Reach a reasoned and honestly-held opinion,
  • Co-operate with the client and instructing legal team,
  • Co-operate with other legal teams when required,
  • Co-operate with other experts,
  • Communicate any change of mind,
  • Comply with the directions of the court.

Tottenham spoke about procedures for selecting expert witnesses, and addressed the pitfalls caused by a lack of proper preparatory work to identify the type of professional expert needed, and whether one was necessary.

Firstly, the legal team needs to identify the issues and the questions the court needs to answer, he advised. This must be confined to the issues between the parties. 

“The expert should not be left to find for himself the questions he has to answer,” he said.

Framing questions

Questions to the expert should preferably be framed as a ‘yes or no’ answer, as in: was there a wrongdoing?; was there a tort or breach of contract?; what injury, loss, or damage was suffered by the plaintiff?

Establishing the answers may require a range of different experts, Tottenham said.

“The parties should try to agree the questions, so you should effectively be sending a document back and forth between the legal teams in order to establish what questions need to be answered,” he suggested.


But he warned that a court will always be sceptical about the need for an expert witness, so the first task is to determine whether one is needed at all.

In professional negligence cases, it’s generally thought safer not to get an Irish expert, since the pool of expertise here is so small.

Expert witnesses do not have to have particular qualification, but they do have to demonstrate expertise — in education and training, professional experience, or special study — which can help address the specific question before the court.

Word-of-mouth recommendations from trusted colleagues are as good a way as any for legal teams to find a good expert witness, Tottenham said.

But an appropriate expert is not one who is likely to give you the answer you want, he warned.

A witness who only assists one side will have their weaknesses exposed in cross-examination, he said.

There is no current database of expert witnesses in this country, he added, though professional bodies may hold themselves out as offering this type of work.

The UK has a number of databases, Tottenham said.

BAILLI should be used as a research tool on the names of expert witnesses, since many of these have been roundly criticised by the courts, with judges calling competence into question in some cases.

Incorrect information

Expert witnesses have been jailed in England for including incorrect information.

Newspaper court report are useful resource also, where a case has not yielded a written judgment.

YouTube videos can offer information on the demeanour of the proposed expert witness.

Ultimately, selection of expert witnesses should be done on the basis of a clear understanding of duties to the court, an ability to carry out the work in a conscientious manner, and to address any issues raised.

Personal belief

Expert witnesses, and lawyers who hire them, must be cognisant of personal beliefs, particularly in cases that involves moral, ethical or religious issues, the webinar heard.

Courts have on occasion criticised expert witnesses for losing their objectivity.

Experts must be mindful of the duty of independence and objectivity, solicitor Caroline Conroy of La Touche Training told the webinar.

Those involved must be alive to how personal belief will weigh in medical cases, for example, concerning such issues as the right to die.

An advocate’s job is to fight a case but an expert witness’s job is to help the judge come to his or her opinion, the webinar heard.

Therapeutic relationships

Pre-existing therapeutic relationships prior to the proceedings must also be guarded against in choosing an expert witness, Caroline Conroy said 

Where an expert has a pecuniary interest in the case, this can throw up the question of bias and conflicted interests.

Courts have given guidance on those matters, she said.

And legal costs accountants have also drawn courts’ attention to certain high levels of expert witness fees.

Many people being called as experts do not fully understand the rigours and demands of this duty, and it is up to instructing counsel to make them clear, she said.

Those instructing expert witnesses must ensure that they are fully aware of and understand their duties.

Financial interest

Any financial or economic interest in the case must also be disclosed, she said.

Mr Justice Michael Peart asked whether the expert witness has the choice to withdraw or change their report, for instance on the request of a defendant in a personal injury case.

Inferences will be drawn from this, he noted.

“I presume you would consider that to be a matter of professional integrity that you would not yield to persuasion to alter the report?

Mark Tottenham replied that in Australia and Canada the legal team can have a role in editing and revising reports to ensure they comply with the rules of admissibility, but lawyers cannot ask for conclusions to be changed.   

Statements of truth 

In the UK, all expert witnesses are to be accompanied by statements of truth, which elevates them to the status of an affidavit or statutory declaration.

A GP in the UK was prosecuted and received a suspended sentence on making a small change to a report on the request of the instructing solicitor, without talking to the injured party, Tottenham said.

The webinar also heard that it is important to distinguish between professional and expert witnesses.


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