When something goes wrong with medical care, most people instinctively feel that a mistake has been made. Proving that a mistake amounts to negligence in the eyes of the law, however, is a very different matter. This is where expert witnesses become central to a medical negligence claim.
Here at McCarthy + Co, our medical negligence solicitors often have the difficult task of advising clients who have had a distressing experience that, without supportive expert evidence, they may not have a viable legal claim. This guide explains what expert witnesses do, why they play such an important role in negligence cases, and the duties they owe to the court.
Why expert evidence is so important
Medical negligence claims in Ireland are judged against the “Dunne principles”, set out by the Supreme Court in Dunne v National Maternity Hospital and reaffirmed by the Supreme Court in Morrissey v HSE in 2020. In simple terms, the test asks whether a practitioner has been guilty of a failure that no other practitioner of equal status and skill would have been guilty of, if acting with ordinary care.
That is a clinical question as much as a legal one. Medical negligence actions in Ireland are heard by a judge sitting without a jury, and a judge cannot be expected to know what a competent obstetrician, radiologist, or surgeon should have done in a particular situation. To succeed, a claim generally needs to establish three things, and expert opinion is required for each:
- A duty of care was owed, which is almost always the case in a treating relationship.
- The care provided fell below the standard of a reasonably competent practitioner.
- That failing caused injury or made the patient’s outcome materially worse.
No claim without a supportive report
One point surprises many people. In Ireland, a solicitor should not issue medical negligence proceedings without first obtaining a supportive opinion from a suitably qualified expert. The Supreme Court made this clear in Cooke v Cronin, and the courts continue to apply it. Commencing a professional negligence action without reasonable, expert-supported grounds may be treated as an abuse of the court’s process.
In practice, this means the expert report is the foundation of the entire case. Before proceedings are issued, your solicitor will gather your medical records and instruct an appropriate specialist to review them. If that expert concludes that the care was reasonable, the claim usually cannot proceed, however upsetting the outcome may have been.
What an expert witness actually does
An expert witness is an experienced clinician, frequently a consultant in the relevant specialty, who is asked to give an impartial professional opinion. Their work involves:
- Reviewing medical records, test results, imaging, and treatment notes.
- Assessing whether the care met the standard expected of a reasonably competent practitioner.
- Identifying any errors or omissions and explaining them in plain terms.
- Addressing causation (meaning whether the failure by the healthcare provider actually caused the injury).
- Preparing a written report and, where necessary, giving evidence at trial.
The specialty of the expert depends on the issues in dispute. A claim about a missed cancer diagnosis might call for a radiologist or an oncologist, while a birth injury claim might require an obstetrician, a midwife, and a neonatologist working alongside one another.
Because Ireland is a small jurisdiction where many consultants know each other, experts are often instructed from the United Kingdom to ensure genuine independence and impartiality.
The expert’s duty to the court
A common misconception is that an expert is there to argue the client’s case. They are not. Under Order 39 of the Rules of the Superior Courts, an expert’s overriding duty is to assist the court, and that duty overrides any obligation to the party paying their fee. Every expert report must contain a statement acknowledging this duty and must disclose any relevant financial interest.
These obligations were strengthened by the Rules of the Superior Courts (Conduct of Trials) 2016. The Irish courts have become increasingly firm with experts who stray into advocacy. In a number of recent judgments, the higher courts have criticised expert witnesses who behaved as “hired guns” rather than independent advisers and have warned that partial or unreliable expert evidence may be excluded, with cost consequences for the party relying on it. For a patient, this is reassuring, because the system is designed to value objectivity over partisanship.
How expert evidence is managed in court
Modern court procedure gives the judge several tools for handling expert evidence efficiently, including:
- Single joint experts, where the parties share one agreed expert.
- Written questions put to an expert about their report.
- Meetings between the opposing experts to narrow the points in dispute.
- “Hot tubbing”, where opposing experts give their evidence concurrently and respond to one another in front of the judge.
Since April 2025, clinical negligence actions in the High Court have been managed within a dedicated Clinical Negligence List, introduced to give these cases focused attention and stronger case management. Under the accompanying procedures, a party generally cannot apply for a trial date until all expert reports have been exchanged. Expert evidence is therefore not a late addition. It shapes the case from the very beginning right through to the final hearing.
A few practical points to keep in mind
- Expert reports take time to obtain, so early advice matters, particularly given the strict two-year time limit, which generally runs from your date of knowledge, that applies to most claims.
- Medical negligence claims do not go through the Injuries Resolution Board and instead proceed directly through the courts.
- An expert’s role is to assess the standard of care objectively. A supportive report is the first hurdle in a claim, and it is not a guarantee of success.
Speak to our medical negligence team
If you are concerned that you or a loved one received substandard medical care, understanding the role of expert evidence is an important first step. At McCarthy + Co Solicitors LLP, our medical negligence team has many years of experience guiding clients through this process. To discuss your situation in confidence, please arrange a consultation using our quick and confidential online form.
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