1. Introduction

This commentary examines the ex tempore judgment of Gillane J in Oonagh Cahill (A Minor) v Health Service Executive [2025] IEHC 624, delivered on 13 November 2025. The case arises in the context of a catastrophic infant brain injury claim, but the judgment itself is procedural: it addresses whether a legally complex issue concerning the personal injury discount rate (PIDR) and taxation can or should be determined as a preliminary issue before trial.

The plaintiff sought to have the Court determine, in advance of the full hearing, whether the calculation of multipliers used to capitalise future loss and expense should explicitly take account of taxes and duties payable on the investment income (and possibly the principal) of any damages award. The defendant opposed this application.

Rather than deciding the underlying question about taxation and discount rates, the High Court refused to order a preliminary trial of that issue. In doing so, Gillane J reaffirmed and sharpened the principles laid down in Campion v South Tipperary County Council [2015] 1 I.R. 716 regarding:

• The default position of a single, unitary trial.
• The stringent conditions governing the use of preliminary issues under Order 25 and Order 34 of the Rules of the Superior Courts (RSC).
• The requirement that a preliminary issue produce real, demonstrable savings in time and cost and be grounded on an agreed or at least workable factual matrix.

The decision is therefore important for:

• Medical negligence and catastrophic injury litigation, where parties may be tempted to carve out discount-rate questions for early determination; and
• The broader law on when courts will entertain abstract or quasi-abstract questions of law divorced from the factual and evidential matrix of the case.

2. Factual and Procedural Background

2.1 The parties and the claim

The plaintiff, Oonagh Cahill, is a minor born on 23 January 2020. She sues by her father and next friend, Ian Cahill. The defendant is the Health Service Executive (HSE), which at all material times operated St. Luke’s General Hospital, Kilkenny.

The plaintiff claims that:

• She presented to hospital in the first days of life with symptoms consistent with intracranial pathology.
• There was a negligent delay in diagnosing hydrocephalus (intracranial pathology).
• That delay allowed the condition to progress, causing severe brain injury and lifelong, major disabilities and impairments.

The case is thus a classic example of high-value, catastrophic personal injury litigation, with complex issues of liability, causation, and very substantial future-care and other heads of damage.

2.2 The procedural posture

A trial date had already been fixed for 11 April 2025. Before that trial date, the plaintiff brought a motion (dated 3 July 2025) seeking an order that a specific question of law be determined as a preliminary issue under:

• Order 25, rule 1 RSC;
• Order 34, rule 2 RSC; or
• The inherent jurisdiction of the High Court.

There was also a separate, unresolved motion regarding genetic testing, which the Court notes will itself be contested. The defence contains some limited admissions, but there remains a full defence on liability and causation, with most factual matters still in dispute.

3. The Proposed Preliminary Issue

The plaintiff framed the preliminary question as follows:

“Should the factors accounted for in determining the adjustment rate(s) (commonly called the personal injury discount rate(s)) to be applied for the purpose of calculating multipliers to be used for the purpose of calculating lump sum damages for future expense/loss streams (i.e. capitalising future expense/loss streams to present value) in a personal injuries action include taxes and duties that will be payable on income earned on such damages (from investment, placement, or other use of the damages) or/and on the principal sum of such damages that is awarded or otherwise recovered?”

In essence, the plaintiff sought early judicial clarification of whether, in personal injuries actions:

• The discount rate(s) used to calculate a lump sum for future losses must explicitly take into account:
  • Taxes and duties on the investment income generated by the damages award; and/or
  • Taxes and duties on the principal amount of the damages itself.

The written submissions for the plaintiff, as noted by the Court, placed “primary” emphasis on:

• Constitutional rights; and
• Rights under the European Convention on Human Rights (ECHR),

presumably arguing that a failure to take post-award taxation properly into account could infringe rights such as bodily integrity, property rights, or the right to an effective remedy. However, the Court did not actually reach or decide these substantive rights-based arguments, because it determined the matter at the level of procedure—specifically, whether it was appropriate to hear the proposed question as a preliminary issue at all.

4. Summary of the Judgment

Gillane J refused the plaintiff’s application to have the discount-rate/taxation question tried as a preliminary issue.

The key reasons, distilled, were:

• Under Campion v South Tipperary County Council, the default is a unitary trial; preliminary issues are exceptional and must be justified by clear savings in time and cost and by convenience.
• In this case, material facts are both disputed and unsettled:
  • There are contested issues on liability and causation.
  • There is an outstanding genetic-testing motion.
  • Parties do not even agree whether evidence is required to resolve the proposed legal question.
• There is no agreed factual matrix on which to base the preliminary issue. The plaintiff says none is needed; the defendant disputes this and points to anticipated evidence from, inter alia, the Office of Wards of Court / Assisted Decision-Making structures, an economist and an actuary.
• The proposed question is damages-related only:
  • It cannot dispose of the proceedings or any distinct cause of action or defence.
  • It may never arise at all if the defendant succeeds on liability or causation.
• No concrete evidence was put before the Court to show that an early decision on this issue would save time or cost or significantly shorten the eventual trial.
• Given the complexity of the underlying claim and the existing trial date, carving out this question at this stage might actually lengthen and complicate the litigation.
• The question as framed is unclear and is not a legal issue that appears in the pleadings:
  • It is ambiguous whether the Court is being asked only to identify the relevant factors, or to fix an actual discount rate for this case.
  • It is not formulated as a pleaded point of law arising on the existing causes of action or defences.

Having weighed these considerations, and applying the principles in Campion and in Vico Properties Ltd v Bank of Scotland plc [2025] IEHC 401, the Court concluded that none of the usual justifications for a preliminary issue (such as disposing of the case, narrowing the issues, or saving time and cost) were satisfied.

The application was therefore refused and the case will proceed to trial on the default unitary basis.

5. Legal Framework: Orders 25 and 34 RSC and the “Unitary Trial”

5.1 Order 25 – Points of law in pleadings

Order 25, rule 1 RSC allows parties to raise points of law in their pleadings. Such points are normally determined by the trial judge at or after trial. However, by consent or on application, they may be “set down for hearing and disposed of at any time before the trial.”

Order 25, rule 2 then permits the Court, where a point of law would substantially dispose of the whole action, or a distinct cause of action or defence, to dismiss the action or make such other appropriate order.

5.2 Order 34 – Special cases and preliminary questions

Order 34 deals with “special cases” and the determination of questions of law. Rule 2 is central here:

“If it appear to the Court that there is in any cause or matter a question of law, which it would be convenient to have decided before any evidence is given or any question or issue of fact is tried … the Court may make an order accordingly…”

The critical element is convenience, understood in a legal sense: whether deciding the question in advance will reduce issues, shorten hearings, or otherwise yield a more efficient and just disposition of the case.

Importantly, Order 34 rule 4 introduces a specific safeguard for cases involving children or persons with impaired capacity, requiring leave of the Court and evidence that the statements affecting the child’s interests are true before a special case is set down. That reflects particular caution in litigation involving vulnerable parties—such as the minor plaintiff in this case.

6. Precedents Cited and Their Influence

6.1 Campion v South Tipperary County Council [2015] 1 I.R. 716

Campion is the central authority. McKechnie J in the Supreme Court articulated a structured approach to applications for the determination of preliminary issues under Orders 25 and 34.

6.1.1 The “unitary trial” as default

The Court in Campion emphasised that the starting point in Irish civil procedure is a single, unitary trial in which all issues of fact and law are determined together. Departures from this model must be justified.

6.1.2 Common purpose of Orders 25 and 34

At paragraph 28 (quoted by Gillane J), McKechnie J stressed that Orders 25 and 34 share a common aim:

“…to save time and cost, when the preliminary process is compared with any other suggested method of hearing, including a full trial of the issues raised… Convenience will also be a consideration…”

He endorsed the test formulated by O’Higgins C.J. in Tara Mines v Minister for Industry and Commerce [1975] 1 I.R. 242:

“In addition, it must appear to the court to be convenient to try such question of law before any evidence is given. This will involve a consideration of the effect on other issues in the case and whether its resolution will reduce these significantly, or shorten the hearing. Convenience in this respect must also be considered in the light of what appears fair, proper and just in the circumstances.”

6.1.3 The Campion criteria (para. 35)

At paragraph 35, McKechnie J set out a series of guiding criteria (quoted extensively by Gillane J) which have become the canonical checklist for preliminary-issue applications:

• No dispute on material facts – Material facts must not be in dispute; they can be agreed or accepted (at least for the purposes of the application).
• Discrete question of law – The question must be clearly legal in character and “distilled from the factual matrix”.
• Time and cost savings – The process must result in measurable savings of time and cost compared to the unitary trial. “Impressions” are insufficient; evidence is usually required.
• Impact on the case – The more the decision would affect the entire case (e.g. by disposing of it or of major issues), the stronger the argument for a preliminary issue.
• Residual substantial issues – If many significant issues would remain regardless of the preliminary decision, the case for a preliminary issue is weakened.
• Exception for stand-alone substantial questions – Exceptionally, a substantial legal question may merit a preliminary determination even if it does not dispose of other issues, if that clearly benefits the action overall.
• Alternative methods – A modular trial or other procedural tools may be more appropriate in some cases.
• “Convenience” from an overall perspective – Convenience is understood broadly as enhancing “the most efficient, timely and cost effective method of disposing of the entire litigation.”
• Consistency with overall justice – Any order must be consistent with fair procedures and the overall justice of the case.
• Caution – Courts should exercise caution to ensure the order achieves its purpose.
• Appellate oversight – An appellate court may substitute its own view where appropriate, while giving weight to the trial judge’s decision.

Gillane J explicitly adopts and applies these criteria. Campion thus forms the backbone of the judgment’s reasoning.

6.2 Vico Properties Ltd v Bank of Scotland plc [2025] IEHC 401

Vico Properties involved an application to determine as a preliminary issue whether certain claims were statute-barred. Statute of limitations questions are often considered classic candidates for preliminary determination because they may dispose of claims entirely.

However, Bolger J refused the application in that case, primarily because:

• There was insufficient agreement on the factual matrix, including on applicable foreign law (English law) and the plaintiff’s intention to plead fraudulent concealment.
• Even a preliminary determination of limitation issues would not deal with all issues in the case.

She concluded:

“I refuse this application and direct that all matters are to be dealt with by way of the default position of a unitary trial.”

Gillane J cites Vico Properties as an illustration that, even for apparently well-suited preliminary issues (like limitation), the absence of an agreed factual matrix and the continuing complexity of the remaining issues can justify refusal. This parallel is directly applicable in Cahill, where:

• Facts are heavily contested.
• There is no agreement even as to whether evidence is required to decide the preliminary question.
• Many issues (liability, causation, and most heads of damages) would remain to be tried.

6.3 Other authorities mentioned

The judgment also references:

• Duffy v News Group Newspapers Ltd (No. 2) [1994] 3 I.R. 63; and
• Croke v Waterford Crystal Ltd (Unreported, High Court, Smyth J, 26 June 2003),

cited in Campion as examples illustrating the efficiency rationale behind preliminary issues.

The classic statement of “convenience” by O’Higgins C.J. in Tara Mines v Minister for Industry and Commerce [1975] 1 I.R. 242 is also quoted, reinforcing that convenience must be assessed in terms of:

• Impact on other issues,
• Reduction in complexity,
• Shortening of the overall hearing, and
• What is fair, proper and just in the circumstances.

7. The Court’s Legal Reasoning

7.1 The absence of an agreed factual matrix

A central pillar of the reasoning is that a preliminary issue must proceed on an agreed or at least clearly accepted factual foundation. Gillane J observes:

“In this case, not only is the evidence which underpins the legal issue not agreed; the parties do not even agree as to whether evidence is required at all for the resolution of the question.” (para. 19)

The defendant pointed to the plaintiff’s own disclosure schedule, which contemplated, among others:

• Unnamed witnesses from the Office of Wards of Court and from the Assisted Decision-Making (ADM) system, to address requirements and costs (unless agreed);
• An economist and an actuary, from whom reports were awaited.

This evidential landscape undermined the plaintiff’s contention that the issue was purely one of law requiring no evidence. The judge concluded:

“It does not seem possible to me to attempt to resolve a legal question absent an accepted underlying factual matrix, even on a pro tem basis, which appears to be completely absent here.” (para. 21)

This echoes the Campion requirement that there be no dispute on the material facts relevant to the preliminary question.

7.2 Limited impact of the proposed issue on the overall case

The Court noted that determining the discount-rate/taxation issue would have limited impact on the broader litigation:

• It is confined to the calculation of future-loss damages.
• The resolution of this issue would not significantly affect the extensive issues remaining on liability, causation, and other heads of damage.
• It could not result in dismissal or disposal of the action, regardless of the Court’s answer.

As the judge put it:

“Another feature of this case is that the resolution of the question posed would not have a substantial impact on the balance of the case. It is manifest from the arguments before me that many substantial issues would still remain for determination.” (para. 22)

And crucially:

“I am also influenced by the fact that the issue in relation to the determination of the adjustment rate to be applied is a damages-related question. It is not a question which, on any view, could bring an end to the proceedings if decided in a particular way.” (para. 25)

This directly engages the Campion guideline that the greater the impact of a preliminary decision on the entire case, the stronger the justification for such an order.

7.3 The possibility that the issue may never arise

A powerful pragmatic consideration is that the question might never need to be answered:

“More importantly, it is a question that may never arise in the case at all.” (para. 26)

If the HSE succeeds on liability or causation, then:

• No damages will be awarded, and
• The question of the appropriate discount rate (and whether it must incorporate tax considerations) will be moot.

The Court emphasises the risk of wasting judicial resources:

“If this issue is determined in advance and the issues relating to causation and liability are subsequently resolved in favour of the defendant, then court resources will in fact have been wasted.” (para. 27)

7.4 Lack of demonstrated time and cost savings

Under Campion, there must be a demonstrable saving of time and cost, usually supported by evidence rather than mere assertion. Here:

“There has been no attempt to identify what would be saved in time and cost if the preliminary issue were to be set down now. It is unclear as to what witnesses, if any, could be disposed of for the trial of the action, and it has not been established that the trial would be shortened by any measurable duration.” (para. 23)

Moreover, the judge notes uncertainty about how long the preliminary hearing itself would take:

“It is not at all clear to me how long the preliminary issue itself would take to hear, which is a further concern in the context of a complicated case for which a trial date has already been set. Rather than shortening the length of the case or narrowing the issues, my sense of the matter, on the basis of the arguments before me, is that separating this issue from the trial could in fact lengthen the case.” (para. 24)

This reasoning is very much in line with the requirement that preliminary processes must enhance overall efficiency, not simply re-arrange litigation stages.

7.5 The nature and timing of the issue: end-of-case damages question

Gillane J considers where in the life-cycle of litigation the discount-rate question properly belongs:

“Even if the question does arise, it is more properly positioned at the end of the case in my view. Having regard to the serious issues that arise in relation to liability and causation, it does not seem readily apparent to me that carving out this issue for a preliminary hearing makes any real practical sense.” (para. 28)

This is a key policy point: discount-rate and tax issues are intimately linked to the specific evidence about the plaintiff’s needs, life expectancy, care regime, and financial arrangements, which is typically developed at trial. Deciding them in the abstract, divorced from that evidence, risks either:

• Merely giving an advisory opinion of limited practical value, or
• Requiring repetition or revision once the actual facts are found at trial.

7.6 Deficiencies in the formulation of the question

The Court also identifies problems in how the preliminary issue was framed:

“I note that the question posed in the notice of motion is not in the form of an issue of law which is itself pleaded in the case.” (para. 29)

And:

“The question posed is unclear as to what the Court is being asked to determine. Is the Court simply to decide whether the factors identified include the taxes and duties payable? Or is the Court to seek to determine an actual rate to be applied in this case?” (para. 30)

This dual ambiguity — is the Court being asked for an abstract pronouncement on factors, or to fix a concrete rate? — further undermines suitability as a preliminary issue under Orders 25 or 34, which presuppose a cleatly defined question of law arising from the pleadings and facts.

7.7 Overall conclusion on convenience and justice

Having considered all these points, the Court concludes:

“It does not appear to me that setting down the preliminary issue as identified for pre-trial hearing would impact the overall proceedings in any of the ways contemplated by McKechnie J. in Campion. There appears to be no identifiable cost saving or efficiency.” (para. 31)

Consequently:

“For these reasons, I am refusing the relief sought in the notice of motion.” (para. 32)

8. Impact and Significance of the Judgment

8.1 Reinforcing a strict approach to preliminary issues

The judgment is a strong reaffirmation that in Irish civil procedure:

• The unitary trial remains the default; and
• Preliminary issues are exceptional, requiring:
  • A discrete question of law,
  • An agreed or clear factual basis, and
  • Realistic, evidenced time and cost savings or significant narrowing of issues.

In complex litigation — particularly in medical negligence and catastrophic injury cases — the Court signals reluctance to fragment proceedings unless there is a compelling case that doing so enhances efficiency and justice.

8.2 Implications for discount-rate litigation

There is an ongoing debate in many jurisdictions (including Ireland) about how to set the personal injury discount rate and whether, and how, to account for:

• Inflation,
• Investment risk, and
• Taxation and transaction costs.

This case demonstrates that the High Court will not readily entertain abstract or near-abstract discount-rate issues in advance of trial merely to provide general guidance. Instead:

• The Court views discount-rate issues as closely tied to the specific evidential context of each case.
• Such issues are seen as belonging, in general, to the damages phase at the end of the case, once liability and causation are established.
• Attempts to litigate broad, quasi-policy issues on discount rates and taxation as preliminary questions will face a high procedural hurdle.

Notably, the Court did not decide whether the law currently requires discount rates to account for post-award taxation. That substantive question remains open for determination in an appropriate case at trial or on appeal.

8.3 Guidance for practitioners

For litigators contemplating preliminary issues, particularly in personal injuries and medical negligence:

• Any proposed preliminary question must be:
  • Tightly drafted, clearly legal in nature, and rooted in the pleadings.
  • Based on a set of facts that are either agreed or accepted for the purpose of the application.
• Practitioners should be prepared to:
  • Identify specific witnesses or topics that would be dispensed with if the preliminary issue is decided early.
  • Provide an evidence-based estimate of time and cost savings.
• It is especially difficult to justify preliminary issues where:
  • Liability and causation are fully contested;
  • A trial date is already fixed;
  • The issue is confined to quantum and does not threaten to resolve or significantly narrow the case; and
  • There is a realistic risk that the issue will prove moot.

8.4 Procedural justice in cases involving minors and vulnerable parties

Although not explicitly foregrounded in the ratio, the procedural safeguards in Order 34 (especially rule 4) and the Court’s careful approach resonate with the need for heightened caution in litigation involving children and potentially life-changing injuries.

The Court’s concern that a poorly chosen preliminary issue might:

• Waste resources,
• Delay resolution, or
• Complicate proceedings unnecessarily,

is particularly acute where the plaintiff is a seriously injured child, and where early, certain compensation (if liability is established) may be critical.

9. Complex Concepts Explained

9.1 “Personal Injury Discount Rate” (PIDR)

When courts award a lump sum to compensate for future losses (e.g., future care costs, loss of earnings, future therapies), they must convert a stream of future expenses into a present-value figure. The idea is that:

• If the plaintiff receives money now, they can invest it and earn a return.
• Therefore, the immediate lump sum should be somewhat less than the simple arithmetic sum of all future payments, because investment returns will make up the difference over time.

The rate used to reflect this is the discount rate. A higher discount rate assumes a higher real return on investment (and therefore reduces the award), whereas a lower discount rate assumes lower returns (and increases the award).

The plaintiff’s proposed preliminary question asks whether the discount-rate calculation must take into account:

• Taxes and duties on the investment income; and
• Taxes and duties (if any) on the principal sums themselves.

If the law requires tax to be considered, that would generally lower the effective discount rate, leading to larger lump sums to ensure the plaintiff is not under-compensated.

9.2 “Preliminary issue”

A preliminary issue is a specific question, often of law, that the Court is asked to decide before the main trial. Reasons for doing so include:

• It might dispose of the case entirely (e.g., a limitation defence).
• It might substantially narrow the issues remaining to be tried.
• It might produce substantial time and cost savings.

However, preliminary issues are only appropriate where:

• The relevant facts are not seriously disputed for the purposes of the issue; and
• The question is clearly legal and discrete.

The dangers of preliminary issues are:

• They can become “mini-trials” that duplicate work;
• They may not in fact dispose of or simplify the case; and
• They risk fragmenting proceedings and delaying final resolution.

9.3 “Unitary trial”

A unitary trial means that all issues of liability, causation, and quantum (damages) are determined together in a single hearing. This is the default model in Irish civil litigation.

The Court in Campion and again in Cahill stresses that departures from this model must be justified by clear advantages in terms of efficiency and justice.

9.4 “Special case” (Order 34 RSC)

A “special case” is a mechanism where parties agree to:

• Set out an agreed statement of facts in a structured document; and
• Ask the Court to decide one or more questions of law based on those agreed facts.

It is a way of presenting the Court with a pure question of law divorced from factual disputes, but it requires genuine agreement on the underlying facts. If parties cannot agree on the facts, or if evidence is needed, a special case (and by extension a preliminary issue) will usually not be suitable.

10. Conclusion: Key Takeaways

Cahill (A Minor) v Health Service Executive [2025] IEHC 624 is not a substantive ruling on whether discount rates in personal injury cases must incorporate tax and duty considerations. That question remains open to be decided in an appropriate factual and procedural setting.

Instead, the judgment’s primary contribution is procedural. It:

• Reaffirms the centrality of the unitary trial as the default mode of civil litigation in Ireland.
• Insists on strict compliance with the criteria laid down in Campion v South Tipperary County Council for the use of preliminary issues:
  • No dispute on relevant material facts (or acceptance of such facts for the purpose of the application);
  • A discrete, clearly legal question that can be distilled from those facts;
  • Demonstrable and substantial time and cost savings;
  • A significant impact on the case as a whole, or at least a substantial, self-contained issue whose early determination clearly benefits the action.
• Emphasises that damages-only questions, particularly those that:
  • Cannot dispose of the action, and
  • May never arise if liability fails,
  are poor candidates for preliminary determination, especially in complex medical negligence litigation.
• Clarifies that courts will be reluctant to entertain abstract or quasi-policy questions (such as the general structure of the discount rate) in the absence of:
  • An agreed factual matrix, and
  • Clear evidence that the exercise will materially improve the efficiency and justice of the proceedings.
• Provides firm guidance that, as a general rule, issues concerning the personal injury discount rate and taxation should be addressed at the damages stage of trial, after the factual and expert evidential foundation is laid.

For the broader legal landscape, the judgment:

• Sets a high procedural threshold for attempts to carve out discount-rate issues as preliminary questions in catastrophic injury cases.
• Supports a cautious, resource-conscious approach to judicial time and litigants’ costs.
• Signals that policy-heavy issues touching on systemic aspects of personal injury compensation are more appropriately decided in the context of concrete facts and at trial, or possibly through legislative intervention, rather than by way of stand-alone, pre-trial legal questions.

In sum, Cahill is a significant procedural decision: it confines the use of preliminary issues in catastrophic medical negligence litigation and reinforces the principle that complex damages questions — such as those concerning the interaction of investment, taxation and the personal injury discount rate — should ordinarily be decided at the end of the case, on a full evidential record.