High Court Emphasizes Expert Evidence in Determining Causation for Delayed Treatment in Herpes Simplex Encephalitis Case

Citation: [2024] EWHC 390 (KB)
Judgment on


In the High Court of Justice case of Gurmukh Gahir v Dr. Ayodele Olusgun Ola [2024] EWHC 390 (KB), a pivotal judgment was handed down regarding the standard of care required from a general practitioner in the context of diagnosing and treating rare viral diseases. The consideration of expert evidence in determining causation for Herpes Simplex Encephalitis (HSE) played a significant role in the outcome of this case. The judgment illuminates the intersection of medicine and law, specifically in the realms of professional negligence and personal injury.

Key Facts

The claimant, Gurmukh Gahir, contracted HSE leading to significant brain injury and permanent disability. The central allegation was that upon presenting to his general practitioner, Dr. Ola, there was a failure to appreciate the severity of his symptoms, leading to a delay in hospital admission and antiviral treatment. It was posited that this delay in administering acyclovir, an antiviral medication, by approximately 55 hours resulted in a poorer outcome than if it had been given promptly.

The judgment centered on two fundamental legal principles:

  1. Bolam Test for Breach of Duty: The Bolam test, stemming from Bolam v Friern Hospital Management Committee [1957] 1 WLR 582, was applied to ascertain whether Dr. Ola breached his duty of care. According to the Bolam principle, a medical professional is not negligent if they act in accordance with a practice accepted as proper by a responsible body of medical opinion, even if others dissent.

  2. Causation: The court examined whether the claimant’s current condition would be materially different if acyclovir treatment had started on the earlier date. The determination of causation hinged on both the “but for” test and the assessment of whether the doctor’s actions materially contributed to the harm.

The court also referred to the Chester v Afshar [2004] UKHL 41 in highlighting that even where a set of outcomes are possible, the claimant only needs to demonstrate that the breach of duty had a material effect on the outcome. Furthermore, the experts used various scales, such as the Extended Glasgow Outcome Scale, to measure the extent of disability and project potential outcomes under different scenarios.

Additionally, reliance on medical literature and expert testimony became paramount in drawing conclusions about the correlation between viral load, immune response, and the effectiveness/timing of treatment in HSE cases.


The court found, on the balance of probabilities, that:

  • The defendant, Dr. Ola, breached his duty of care by failing to promptly refer the claimant to the hospital upon presentation of symptoms consistent with HSE.
  • Had the defendant not breached his duty of care, it is probable that the claimant would have received acyclovir treatment approximately 55 hours earlier.
  • The claimant’s neural damage and subsequent disability could have been significantly reduced had the treatment started on the basis of earlier referral, thereby affecting the claimant’s outcome and resulting in less severe disabilities.

The court favored the expert opinion with more substantial clinical experience and recent academic research, Professor Michael, over Dr. Turner’s and Dr. Baker’s theories due to doubts cast on the reliability of the literature they cited and the smaller number of cases they had personally encountered.


In Gurmukh Gahir v Dr. Ayodele Olusgun Ola, the High Court emphasized the adherence to the Bolam test in assessing the standard of care afforded by medical professionals. The case signifies a meticulous application of legal principles concerning professional negligence leading to personal injury. While adopting a holistic approach, the court also underscored the importance of substantial clinical experience and contemporary studies when considering expert testimony to establish causation between delayed medical treatment and the severity of health outcomes. This judgment furnishes legal practitioners with a comprehensive understanding of the nexus between clinical negligence and patient harm within UK jurisprudence.

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