Stays for Refusal of Genetic Testing: Relevance-First and Heightened Materiality for Sensitive “Trio Exome” Evidence

1. Introduction

C. (A Minor) v Health Service Executive (Approved) [2026] IEHC 234 is an interlocutory decision of the High Court (Simons J) in a clinical negligence action. The claimant is a child suing by a parent as next friend. The defendant (the Health Service Executive) sought a stay of the proceedings unless the child and both parents: (i) attended an examination by the defendant’s consultant clinical geneticist, and (ii) provided buccal swabs for trio exome sequencing.

The core dispute was whether the defendant was entitled, in the interests of a fair trial, to obtain potentially causation-determinative genetic evidence, notwithstanding the claimant family’s objections grounded in privacy, autonomy, confidentiality, and data-security concerns.

The judgment is also notable for: (a) a structured approach to the legal test for stays where medical testing is refused; (b) careful treatment of highly sensitive genetic evidence; and (c) a firm stance on the inadmissibility of non-expert critique of scientific evidence in affidavit form.

2. Summary of the Judgment

  • The Court reaffirmed the High Court’s inherent jurisdiction to stay personal injuries proceedings where a plaintiff refuses a medical examination, as confirmed by McGrory v. Electricity Supply Board [2003] 3 IR 407.
  • Simons J articulated a two-limb framework:
    1. Relevance/materiality threshold: the proposed examination/testing must be directed to eliciting information relevant to issues in controversy.
    2. Balancing/proportionality: once relevance is established, the Court balances likely probative value against interference with rights (privacy, confidentiality, bodily integrity), with proportionality inherent in this limb.
  • The Court rejected the need to import a separate, “third-stage” proportionality step from English authority (notably Clarke v. Poole [2024] EWHC 1509 (KB), leave granted in Clarke v. Poole [2025] EWCA Civ 447), holding Irish law already requires a fairness-based balancing exercise.
  • On the uncontradicted expert evidence, the Court held trio exome sequencing was not merely relevant but likely to have a “meaningful bearing” on outcome, including on causation.
  • The Court stayed the action until the child and parents underwent the proposed examination and provided buccal swabs.
  • Costs were awarded to the successful moving party in principle, with execution stayed until after High Court determination of the main action; the Court referenced Order 99, rule 3, section 169 Legal Services Regulation Act 2015, and ACC Bank plc v. Hanrahan [2014] IESC 40.

3. Analysis

3.1 The governing Irish jurisdiction: stay for refusal of medical examination

The decision proceeds from the established proposition in McGrory v. Electricity Supply Board [2003] 3 IR 407 that the courts possess an inherent jurisdiction to stay personal injuries proceedings where justice requires it because a plaintiff refuses a medical examination. McGrory’s rationale—central to Simons J’s approach—is that a plaintiff who sues for personal injuries “by implication necessarily waives” medical privacy to the extent necessary to avoid unfairly impeding the defendant’s preparation of its defence.

3.2 The legal test: a two-limb approach with proportionality embedded

A significant contribution of the judgment is its clarification of the analytical structure for stay applications involving sensitive testing. The Court held that the correct Irish approach is not a rigid three-stage test, but rather:

  1. Relevance/materiality: The defendant must demonstrate the examination/testing is aimed at obtaining information relevant to the issues between the parties.
  2. Balancing of rights (including proportionality): The Court then weighs the likely material value of the information against the degree of interference with the plaintiff’s rights (privacy, confidentiality, bodily integrity). Proportionality is not a discrete third step; it is “inherent” in the second limb.

In shaping this, Simons J drew an analogy with confidential discovery, relying on the Court of Appeal’s guidance in Ryan v. Dengrove DAC [2022] IECA 155. In Ryan, confidentiality “must ultimately yield to the interests of justice,” but disclosure requires a real basis for relevance, and the higher the confidentiality, the more exacting the relevance showing. Simons J transposed that logic to the medical-testing context.

3.3 Heightened scrutiny for genetic (and similarly sensitive) testing

The Court expressly recognised that certain categories of testing engage “heightened medical confidentiality or sensitivity,” giving genetic testing as a prime example. The judgment therefore sets a practical calibration rule:

Where a party seeks a specific test engaging heightened sensitivity (e.g. genetic or neuro-physiological testing), the Court will require a correspondingly clear demonstration that the results will likely have “some meaningful bearing” on outcome.

This does not create a new jurisdictional hurdle, but it does sharpen the evidential and argumentative burden on the moving party where privacy impacts are especially acute. The Court’s insistence on “meaningful bearing” functions as a proportionality proxy: sensitive testing must justify itself by probative value, not curiosity.

3.4 Application to trio exome sequencing: why relevance/materiality was met

The defendant’s expert evidence—unchallenged by any countervailing medical evidence—was that the child’s constellation of features made an underlying genetic diagnosis likely, and that prior investigations were incomplete for the question at hand. The proposed trio exome approach (child plus both parents as comparators) was described as “gold standard” in such presentations and potentially diagnostic in a substantial proportion of cases.

Crucially, the Court treated the genetic evidence as potentially dispositive on causation. If the child’s phenotype were explained genetically and no expert evidence established that the admitted delays in February 2020 contributed to the outcome, the claim could fail (while emphasising that the claimant remained free to call causation evidence at trial).

3.5 The “indivisible injury” strategy and why it did not defeat relevance

The claimant argued, in essence, that because the defendant admitted certain breaches (failure to measure head circumference and potential earlier diagnosis), the claimant could recover for the entire presentation on an “indivisible injury” basis if the negligence contributed more than negligibly. The Court rejected using that submission to negate the relevance of genetic testing, for a simple reason: at this interlocutory stage there was no expert evidence establishing any biological mechanism of contribution from the admitted breaches to the claimed impairments.

Simons J distinguished the English authorities relied upon:

  • CNZ (by her father and litigation friend MNZ) v. Royal Bath Hospitals NHS Foundation Trust [2023] EWHC 19 (KB), 192 BMLR 94: contribution was analysed within a well-understood hypoxic-ischaemic process, with clear expert evidence of a causal pathway; the dispute was largely quantification once contribution was established.
  • Bailey (by her father and litigation friend) v. Ministry of Defence [2008] EWCA Civ 883, [2009] 1 WLR 1052, 103 BMLR 134 and Williams v. Bermuda Hospitals Board [2016] UKPC 4, [2016] AC 888, 150 BMLR 1: both confirm material contribution principles in appropriate contexts, but do not license findings of contribution in the absence of evidence.

The practical effect is that defendants faced with an asserted “indivisible injury” approach may still obtain genetic testing where it is plausibly capable of separating genetic causation from alleged negligent contribution—particularly where the claimant has not yet put forward cogent expert causation evidence.

3.6 The balancing exercise: privacy, family implications, incidental findings, and data security

The Court accepted the legitimacy of the family’s objections as rights-based concerns, including the reality that genetic information can engage the interests of biological relatives. However, it concluded that the defendant’s proposed safeguards sufficiently mitigated those impacts, including:

  • non-invasive buccal swabbing;
  • pre-test counselling and documented consent;
  • phenotype-driven analysis and constrained reporting practices (e.g., no routine reporting of adult-onset risks in a child, and no healthy carrier status);
  • secure handling and limited retention of DNA for defined purposes;
  • use of accredited laboratories and defined quality systems;
  • option of referral to a different consultant geneticist if preferred;
  • post-test counselling and appropriate clinical signposting.

On that basis, the Court held the defendant’s right to defend the proceedings would be unfairly impeded without the testing, and the stay was proportionate.

3.7 Parents as “third parties”: litigation reality over formal labels

A further point of practical significance is the Court’s refusal to treat the parents as irrelevant “third parties” whose cooperation could not be required. The parent acting as next friend was directing the litigation on the child’s behalf. In that procedural context, trio testing’s reliance on parental comparators was treated as intrinsic to obtaining meaningful evidence, not as an improper attempt to compel unrelated individuals.

3.8 Evidence and procedure: limits of solicitor affidavits on scientific matters

Simons J criticised the attempt to challenge expert genetic evidence through a solicitor affidavit containing scientific critique, describing it as “entirely inappropriate.” The point is not merely rhetorical: it underscores that where sensitive testing is sought, resistance must ordinarily be mounted (if at all) through admissible expert evidence addressing utility, necessity, proportionality, and safeguards—rather than through argument dressed as “evidence.”

3.9 Impact

  • Structured Irish test for sensitive examinations: The judgment consolidates an Irish, relevance-first framework and discourages over-complication by importing multi-stage English formulations where domestic principles already demand a balancing exercise.
  • Genetic testing as mainstream litigation evidence: Trio exome sequencing is treated as potentially central to causation, not merely an exploratory or collateral inquiry. Future defendants in complex paediatric neurodevelopmental claims are likely to cite this decision when seeking genomic testing to investigate alternative causation.
  • “Meaningful bearing” threshold rises with sensitivity: The more intrusive or confidential the proposed test, the clearer the evidential demonstration required. This encourages focused, phenotype-driven testing proposals with robust safeguards.
  • Procedural discipline: Parties opposing testing should expect to meet expert evidence with expert evidence, particularly on data security, lab standards, and reporting scope.

4. Complex Concepts Simplified

  • Stay of proceedings: a pause ordered by the court. Here, the case cannot move forward until the examination and swabs are provided.
  • Trio exome sequencing: sequencing the protein-coding regions of DNA (the “exome”) for the child and both parents. Comparing the trio helps determine whether a variant is inherited or new, improving interpretation and diagnostic confidence.
  • Relevance/materiality: whether the information is likely to matter to the issues the trial must decide (here, especially causation).
  • Balancing/proportionality: weighing the usefulness of the evidence against the intrusion into rights; more sensitive evidence requires stronger justification and safeguards.
  • Indivisible injury/material contribution (in broad terms): where multiple causes contribute to a single injury that cannot be divided into separate parts, a claimant may succeed if negligent contribution is established as more than negligible—but only on the basis of evidence establishing contribution in the first place.

5. Conclusion

C. (A Minor) v Health Service Executive [2026] IEHC 234 confirms that Irish courts will stay personal injuries proceedings where refusal to undergo a relevant medical examination would unfairly impede a defendant’s ability to defend itself. The judgment crystallises a practical two-limb approach—relevance first, then a rights-based balancing exercise with proportionality embedded—and signals that for highly sensitive genetic testing the court will demand a clear showing of likely “meaningful bearing” on the case. On the facts, robust proposed safeguards and uncontradicted expert evidence justified a stay pending trio exome sequencing of the child and parents.