Wilsher v Essex Area Health Authority

Factual and Procedural Background

The Respondent was born almost three months prematurely on 15 December 1978 with a birth-weight of approximately 1,200 grams. During neonatal care at The Hospital’s special baby unit, he was exposed to abnormally high arterial oxygen levels on several occasions. He later developed retrolental fibroplasia (RLF), an eye condition that left him blind in one eye and with severe impairment in the other.

The Respondent sued the Appellants—an area health authority responsible for The Hospital—alleging that negligent management of his oxygen supply caused or materially contributed to his RLF. After a 20-day High Court trial before Judge Pain, judgment was entered for the Respondent for £116,199.14. The Court of Appeal, by a majority, upheld the finding of negligence but overturned most of the trial judge’s reasoning on the burden of proof; it nevertheless maintained liability on causation grounds. The Appellants obtained leave to appeal to the House of Lords, which heard argument over six days in February 1988 and delivered judgment on 10 March 1988.

Legal Issues Presented

1. Whether, on the evidence, the Appellants’ admitted negligence in misplacing an umbilical arterial catheter caused or materially contributed to the Respondent’s RLF.
2. Whether McGhee v. National Coal Board modifies the ordinary burden of proof on causation so that, once a defendant’s breach increases the risk of injury, the onus shifts to the defendant to disprove causation.
3. Whether the Court of Appeal was entitled to make additional findings of medical fact (i.e., that the oxygen levels were capable of causing RLF) notwithstanding the trial judge’s limited findings.

Arguments of the Parties

Appellants' Arguments

• The trial judge erred in reversing the burden of proof on causation; under Bonnington Castings v. Wardlaw, the Respondent must prove on the balance of probabilities that negligence caused the injury.
• McGhee does not establish any legal principle shifting the onus; it merely permits an inference of causation on particular facts, which are distinguishable from the present case.
• The medical evidence showed that any elevation in the Respondent’s arterial oxygen tension was not sufficiently high or prolonged to have caused RLF.
• The Court of Appeal exceeded its proper role by making fresh findings of expert fact without seeing the witnesses.

Respondent's Arguments

• The misplacement of the catheter and subsequent periods of high oxygen materially increased the risk of RLF; under McGhee, this suffices to establish causation unless the Appellants disprove it.
• The evidence of the Respondent’s experts supported the conclusion that excessive oxygen was probably at least a contributory cause.
• The trial judge’s finding that the Appellants failed to show their negligence “did no harm” should be read as an affirmative finding for the Respondent, even if the burden of proof were not reversed.
• A retrial would be oppressive and unnecessary because the Court of Appeal properly inferred causation.

Table of Precedents Cited

Court's Reasoning and Analysis

The House, speaking principally through Judge Bridge, reaffirmed that the ordinary civil burden—proof on the balance of probabilities—rests on the plaintiff. The trial judge had explicitly placed the onus on the Appellants to show that their negligence “did no harm,” relying on his reading of McGhee. The House held this to be a misinterpretation: McGhee did not establish a legal rule reversing the burden of proof; it merely permitted a factual inference where evidence justified it. Moreover, the factual matrix of McGhee—with only one possible injurious agent (brick dust)—was materially different from the present case, where several independent neonatal conditions (hypercarbia, intraventricular haemorrhage, apnoea, patent ductus arteriosus) could also have caused RLF.

Because the trial judge evaluated causation under an incorrect legal test and analysed the expert evidence only briefly (two and a half transcript pages out of sixty-eight), his findings on causation could not stand. The Court of Appeal’s attempt to salvage the decision by making its own factual findings was impermissible: resolution of highly technical expert disputes requires a first-instance judge who has heard and assessed the witnesses. Consequently, the House concluded that justice required a fresh trial limited to causation.

Holding and Implications

APPEAL ALLOWED; PRIOR ORDERS SET ASIDE (SAVE AS TO COSTS); MATTER REMITTED FOR RETRIAL OF CAUSATION BEFORE A DIFFERENT JUDGE.

Immediate effect: the damages award is vacated, monies paid into court remain pending, and the Respondent is granted legal-aid taxation of costs in the House of Lords. Broader implications: the judgment clarifies that McGhee does not shift the burden of proof; plaintiffs in medical-negligence cases must still prove, on the balance of probabilities, that negligence caused or materially contributed to their injury. No new precedent on liability was created, but the decision re-emphasises orthodox causation principles and limits any expansion of risk-based liability.