Expert Witnesses in Personal Injury Claims in Ireland

What an Expert Witness Is Under Irish Law

An expert witness gives opinion evidence, where an ordinary witness may give only evidence of fact. In an Irish personal injury claim, most witnesses can describe only what they saw, did, or experienced. An expert is the exception. Because of specialist training and experience, an expert may interpret facts and offer a reasoned opinion on matters outside the ordinary knowledge of the court, such as a medical prognosis, the cause of a collision, or the cost of future care.

The Rules of the Superior Courts define the field broadly. The relevant definition of an expert "report" in Order 39 extends to accountants, actuaries, architects, dentists, doctors, engineers, occupational therapists, psychologists, psychiatrists, scientists, and any other expert. Expert evidence is near-universal in litigated injury and medical negligence cases in Ireland, even though the great majority of claims settle, or are assessed by the Injuries Resolution Board, long before a hearing.

This distinction matters in a practical way that surprises many claimants. Your own treating doctor, the GP or consultant who looked after you, is usually a witness of fact. They can describe what they found and what they did. They are not, by default, your independent expert on prognosis or liability, because their prior relationship with you sits uneasily with the independence the court requires. An independent expert is retained specifically to assist the court, and that role carries a duty explained in the next section.

The Overriding Duty to the Court (Order 39 Rule 57)

An expert's first duty is to the court, and it overrides any obligation to the party paying the fee. This is the single most important rule governing expert evidence in Ireland, and it is set out in plain terms. Per Order 39, Rule 57(1) of the Rules of the Superior Courts, inserted by S.I. No. 254 of 2016:

"It is the duty of an expert to assist the Court as to matters within his or her field of expertise. This duty overrides any obligation to any party paying the fee of the expert."

Order 39, Rule 57(1), Rules of the Superior Courts

The rule also imposes formal obligations on the report itself. Under Rule 57(2), every expert report must contain a statement acknowledging that duty to the court, and must disclose any financial or economic interest the expert, or a person connected with the expert, holds in the business or activity of the party who retained them, beyond the agreed fee for the report and attendance. The declaration is not a formality. It is the mechanism by which the court tests whether the opinion in front of it is genuinely independent.

These obligations did not appear from nowhere. They restate principles long recognised at common law and usually traced to the English decision in National Justice Compania Naviera SA v Prudential Assurance Co Ltd ("The Ikarian Reefer") [1993] 2 Lloyd's Rep 68. That case held that expert evidence should be the independent product of the expert, uninfluenced by the pressures of litigation, and that an expert should never assume the role of advocate. The principles, as approved in Irish judgments, require an expert to:

• give evidence that is the independent product of the expert, uninfluenced by the pressures of the litigation;
• provide objective, unbiased opinion confined to matters within their expertise;
• state the facts and assumptions on which the opinion rests, and any matter that could detract from it;
• make clear where a question or issue falls outside their expertise; and
• communicate any change of opinion to the other side and the court without delay.

Irish courts treat those principles as persuasive and have repeatedly approved them. As the Law Society's Gazette put it in its 2024 review of the area, their essence is now reflected directly in Order 39, Rule 57(1).

When Expert Evidence Becomes Inadmissible

In Ireland, a partisan expert risks having their evidence excluded altogether, not merely given less weight. For many years the consequence of an expert straying into advocacy was that the trial judge discounted the evidence. The Court of Appeal has signalled a firmer approach. In Duffy v McGee [2022] IECA 254, a personal injuries claim about exposure to spray-foam insulation, the trial judge had excluded a defendant's expert toxicologist entirely, and the Court of Appeal upheld that decision.

"There was in this case such an abject failure to comply with the most basic obligation of an expert, namely, to be objective and impartial, as to render all of [the] evidence inadmissible."

Court of Appeal in Duffy v McGee [2022] IECA 254

The point of principle is that a failure of independence can go to admissibility, not just to weight. In a concurring judgment, Collins J described the culture of experts acting as advocates for the party retaining them and said, bluntly, that there "needs to be a significant change of culture in this area." He also placed responsibility on the lawyers. Counsel and solicitors who put an expert forward must satisfy themselves that the witness understands and can comply with the Order 39 duty, and if not, the witness should not be proffered.

The Court of Appeal had set the tone earlier in Byrne v Ardenheath Company Ltd [2017] IECA 293, where Irvine J observed that expert opinions "all too often appeared to correspond too favourably with the interests of the parties who retained them," and that ordinary common sense must be brought to bear when assessing expert evidence in non-specialist cases. The current direction of travel is clear, and any reader weighing the strength of a claim should understand it: independence is not a matter of presentation. It is a condition of being heard.

Independence also imposes a positive duty, not just a prohibition on advocacy. An expert must ascertain and present all material facts, including those that do not assist the party who retained them. In Waliszewski v McArthur & Company Ltd [2015] IEHC 264 the High Court, per Barton J, described an expert's failure to deal fully with the relevant issues as "reprehensible". Selective evidence is treated as a breach of the duty to the court, not a tactical choice. This matters in practice because most injury claims are assessed by the Injuries Resolution Board and resolved without a hearing; in the minority that reach a contested trial, expert evidence is near-universal, and its credibility is tested hard.

One feature of Irish practice is worth stating precisely, because it is often misunderstood by reference to other jurisdictions. Irish courts do not operate a formal "gatekeeping" filter that screens expert evidence for scientific reliability before it is admitted, of the kind associated with the United States. Concerns about the reliability of an expert's methods generally affect the weight the court gives the evidence, rather than whether it is admitted at all. Independence is the threshold question; reliability is, for the most part, a question of weight.

The leading Irish authorities on expert evidence can be summarised as follows:

Types of Expert Witness in Irish Personal Injury Claims

Different stages of a claim call for different experts, and most of them are not doctors. Proving liability, establishing prognosis, and calculating the value of a serious claim are distinct tasks. Each tends to need its own specialist. The table below sets out the main categories used in Irish personal injuries litigation, with a link to the dedicated guide for each. Note that proving a breach of the standard of care in a clinical case is a separate exercise governed by the Dunne principles, covered in our breach of duty guide, rather than on this page.

A serious catastrophic claim shows how these roles connect. A medical expert sets the prognosis and life expectancy. A care expert and an occupational therapist then quantify the future care and equipment needs. A vocational expert assesses what work, if any, the injured person can return to. Finally, an actuary converts all of that into a present-day figure the court can award. The detail of each link in that chain belongs on the dedicated guides above; this page explains the rules that apply to every one of them.

Where Do the Limits of Expert Evidence Lie in Irish Practice?

The duty to the court sets the standard, but several procedural rules and one unsettled question define its boundaries. Having set out what an expert is and the duty they owe, the remaining questions in Irish injury practice are practical and procedural. How and when must reports be exchanged? How much expert evidence will the court permit? How are clinical negligence cases now managed? And can an expert who gets it badly wrong be sued? The sections that follow address each in turn.

Disclosure, Exchange and Restriction of Reports

Expert reports intended to be used at trial must be exchanged in advance, and the volume of expert evidence is controlled by the court. Order 39 sets out a timetable for the exchange of reports between the parties once a case is set down, so that neither side is taken by surprise at the hearing. Reports an expert prepares but the party does not intend to rely on at trial sit in a more complex position, and the disclosure regime around draft and preliminary reports has been the subject of judicial criticism. The practical lesson is that the instructing solicitor's letter of instruction should be precise from the outset.

The court also controls how much expert evidence it will hear. Per Order 39, Rule 58(1), "expert evidence shall be restricted to that which is reasonably required to enable the Court to determine the proceedings." That rule exists to prevent the historic problem of well-resourced parties overwhelming a case with overlapping experts. In Duffy v McGee, Collins J cited Rule 58 directly when noting how expert testimony can needlessly lengthen trials.

Who instructs the expert can itself be raised at trial. In McLaughlin v Dealey & Anor [2023] IEHC 106, the defendant argued that less weight should attach to an orthopaedic surgeon's evidence because the plaintiff's solicitor, rather than her GP, had referred her. Ferriter J rejected that as a general objection. He held that a solicitor is entitled to advise a plaintiff to engage a medical expert, provided the expert is properly briefed with the relevant history and acts in accordance with the overriding duty to the court. The evidence was given full weight. Following that decision, the Law Society of Ireland issued a protocol on the commissioning of medical reports by solicitors.

The Clinical Negligence List and 2025 Practice Directions

Since April 2025, clinical negligence cases are actively case-managed, with expert evidence front-loaded. Two High Court Practice Directions, HC131 and HC132, took effect on 28 April 2025 and created a dedicated Clinical Negligence List with much tighter control over expert evidence. The judge managing the list can set timetables for the exchange of expert reports, direct the parties to mediation, and make orders about witness statements and expert evidence. The aim is to end the practice of "trial by ambush," where key expert evidence appeared only on the courthouse steps.

The practical consequence for litigants is significant. A party can no longer leave the costly business of instructing experts until the eve of trial. Reports and witness lists must be exchanged, or offered, before a trial date is fixed. That front-loading shifts the timing of the financial commitment in a serious claim. The reforms apply to clinical negligence, and the detail belongs with our medical experts guide and joint expert reports guide rather than here. The same drive toward court-controlled evidence sits behind the growing use of the expert conference, or "conclave", and of concurrent evidence (informally, "hot-tubbing"), where opposing experts are sworn together and examined side by side; both are covered in our joint expert reports guide.

Expert Immunity from Suit: the Unsettled Irish Position

Whether an Irish expert witness can be sued for negligent evidence is not settled. In England and Wales, the long-standing immunity that protected expert witnesses from being sued by the party who retained them was removed by the United Kingdom Supreme Court in Jones v Kaney [2011] UKSC 13. That decision is persuasive only; it does not bind Irish courts, and the question has not been resolved here in the same definitive way.

The Law Reform Commission examined expert evidence in its 2016 report (LRC 117-2016) on aspects of the law of evidence and has recommended reform, including placing the expert's duty on a statutory footing and removing immunity in cases of gross negligence. Until the Oireachtas legislates or a suitable case reaches the higher courts, the prudent position is to treat the scope of any immunity as uncertain. This is one of several areas where commentators note that the Irish rules on expert evidence remain scattered across rules of court, case law, and practice directions rather than consolidated in a single source.

Who Pays for Expert Witnesses, and Are the Fees Recoverable?

The party calling an expert usually pays the fee first, and may recover it from the other side if the claim succeeds. In an Irish injury claim the expert's fee is normally met up front by the claimant or, in practice, by the instructing solicitor, and it forms part of the legal costs of the case. Because costs ordinarily follow the event, a successful claimant can generally recover reasonable expert fees from the unsuccessful defendant.

Recovery is not automatic in full. Expert fees are subject to adjudication of costs, and a Legal Costs Adjudicator may reduce a fee that was disproportionate or not reasonably incurred. The Order 39, Rule 58 principle that expert evidence is limited to what is reasonably required feeds directly into that assessment, because evidence the court did not need is harder to justify as a recoverable cost. Where a claim is modest or the technical issue is narrow, a single agreed expert can keep the cost proportionate while still meeting the duty to the court. The detail of how each category of expert is instructed and costed is dealt with on the dedicated guides linked above.

Frequently Asked Questions