Case Facts
The claimant suffered from severe back pain and was referred to the defendant, an eminent consultant neurosurgeon, who advised her to undergo spinal surgery. Three days after the consultation, the surgeon performed the operation with the claimant's consent. Although the operation was carried out competently and without error, it resulted in significant nerve damage, leaving the claimant partially paralysed. Crucially, this damage was not an unexpected complication; it was a known inherent risk of the procedure, estimated at approximately 1–2%.
The trial judge found as a fact that the surgeon had failed to inform the claimant of this risk, and that this failure was negligent. The judge further found that, had she been properly warned, the claimant would not have consented to the operation taking place at that time. Instead, she would have sought a second opinion, and possibly a third, before deciding how to proceed. Significantly, the trial judge made no finding — and was not invited to make one — that if she had been properly advised, the claimant would never have undergone the operation at any later date. Had she undergone surgery at a later date, the inherent risk of nerve damage would have been exactly the same. The defendant surgeon appealed against the Court of Appeal decision, which had affirmed the first-instance judgment in the claimant's favour.
Held
The House of Lords dismissed the surgeon's appeal by a 3–2 majority, with Lord Bingham of Cornhill and Lord Hoffmann dissenting.
The majority held that the claimant did not need to prove that she would never have consented to undergo the operation at any time if she had been properly warned of the risks. It was sufficient for her to establish that, had she been properly warned, she would not have consented to the specific operation which was in fact performed on that occasion — and which resulted in the very injury about which she should have been warned.
The majority explicitly acknowledged that this conclusion could not be reached on the basis of conventional causation principles. The failure to warn had not created or increased the risk of injury, nor had it lessened the claimant's chances of avoiding it. Nevertheless, the departure from orthodox but-for causation was justified on policy grounds rooted in the protection of patient autonomy.
The majority held that the injury suffered was the product of the very risk about which the claimant ought to have been warned before giving her consent. It could therefore properly be regarded as having been caused, in the legal sense, by the breach of the duty to warn.
Ratio Decidendi
The central legal question before the House of Lords was one of causation only. The surgeon's negligence in failing to warn and the existence of a duty to disclose the risk were not in dispute; the sole issue was whether the causal link required to establish liability had been made out.
The surgeon's argument on appeal was that, to establish causation in a failure-to-warn case, the patient must prove not merely that she would not have accepted the risk at the time in question, but that she would not at any time have consented to run that risk. The majority emphatically rejected this argument.
The ratio of the case is that causation is established in a failure-to-warn claim where the patient proves: (1) that she would not have consented to the operation as performed if she had been properly warned; and (2) that the injury suffered was the product of the very risk about which she should have been warned. In such circumstances, the injury may be regarded as caused, in the legal sense, by the breach of the duty to warn.
The majority was candid that this test cannot be justified by reference to conventional causation doctrine. Under orthodox principles — such as the but-for test applied in Barnett v Chelsea and Kensington Hospital [1969] — the failure to warn did not alter the statistical probability of the injury occurring. The risk was the same whenever the surgery might have taken place. The modification was therefore expressly justified on policy grounds. The law imposing the duty to warn had at its heart the right of the patient to make an informed choice as to whether, and if so when and by whom, to be operated on. To leave without a remedy a patient who would find the decision difficult — one who might have sought further advice or deferred surgery rather than refusing it outright — would render the duty to warn useless in precisely the cases where it was most needed. It would also discriminate against those who could not honestly say they would have declined the operation once and for all.
The function of the law, as articulated by the majority, is to enable rights to be vindicated and to provide remedies when duties have been breached. Unless the duty to warn is backed by an effective remedy, it becomes hollow, stripped of all practical force, and loses its ability to protect the patient.
The majority drew support from the Australian High Court decision in Chappel v Hart [1999], which was adopted as persuasive authority. The broader doctrinal landscape against which the case was decided includes Bolam v Friern Hospital Management Committee [1957], which establishes the standard of care for clinical judgment generally, and Fairchild v Glenhaven Funeral Services Ltd [2002], in which the House of Lords had similarly modified conventional causation principles on policy grounds in the context of mesothelioma caused by exposure to asbestos from multiple employers.
It should be noted that the Bolam standard, whilst relevant to clinical negligence more broadly, does not govern the duty to warn of material risks. That duty — confirmed by the Court of Appeal in Pearce v United Bristol Healthcare NHS Trust [1998] and now authoritatively restated in Montgomery v Lanarkshire Health Board [2015] — requires disclosure of risks that a reasonable patient would consider significant. The House of Lords in the present case proceeded on the basis that the duty and its breach were already established; it was not asked to reconsider the content of the duty to warn.
Obiter Dicta
The dissenting opinions of Lord Bingham of Cornhill and Lord Hoffmann are of considerable importance, not least because they illuminate the doctrinal tension at the heart of the decision. Both dissenting members took the view that the modification of conventional causation principles was impermissible. Lord Hoffmann, in particular, reasoned that the majority's approach produced a result in which the defendant was held liable for an injury that he had not caused in any meaningful sense, since the risk would have been the same had the operation been performed at any other time. In his view, the duty to warn should be vindicated through appropriate recognition of the patient's right to make an informed choice, but that vindication should not involve a distortion of the law of causation.
The majority opinions also contain observations — which may be regarded as obiter — concerning the broader significance of patient autonomy as a value informing the law of tort. Several of their Lordships emphasised that the modern law must be responsive to the patient's right to control what is done to their own body, a right that would be rendered nugatory if causation doctrine systematically excluded from relief those patients who, on being properly advised, would have deferred rather than permanently declined a procedure.