The failure to warn cases
87The Plaintiff relies on the reasoning in two leading failure to warn cases - Chappel v Hart in the High Court of Australia, and Chester v Afshar [2005] 1 AC 134 in the House of Lords - as supporting a conclusion that causation is established in her case.
88In Chappel v Hart, Dr Chappel had failed to warn Mrs Hart of a very small but inherent risk of perforation of the oesophagus and infection associated with throat surgery that he performed on her. This risk had been the subject of a specific inquiry by Mrs Hart, and had she known of it, she would not have had the surgery on that occasion, but would have sought out the most experienced surgeon in the field. The risk materialized. By a majority of three to two, the High Court held that Dr Chappel's negligence was a cause of the harm suffered by Mrs Hart, notwithstanding that the risk was inherent in the procedure and that she would have been exposed to that risk even if she had received an appropriate warning from Dr Chappel and the surgery had been performed at a later time by a different surgeon.
89The majority was constituted by Gaudron, Gummow and Kirby JJ, in separate judgments. Gaudron J (at [11]) explained that Dr Chappel's argument, that his failure to warn Mrs Hart of the risks involved was not causally related to her injuries, had two aspects: first, that as surgery was inevitable and the risk that eventuated inherent in it, she did not in fact suffer any damage; and secondly, that the harm resulted from the "random risk" of infection and her voluntary willingness to undertake that risk. Her Honour rejected (at [12]) the first, on the basis that it fallaciously assumed that the degree of risk was the same regardless of the experience of the surgeon concerned, and (more fundamentally) that it proceeded on the erroneous footing that the damage sustained was exposure to risk, not the harm that eventuated: "To say that Mrs Hart would inevitably have been exposed to risk of the harm which she suffered is not to say that she would inevitably have suffered the harm". And her Honour rejected the second (at [14]), because it treated the infection which occurred as a supervening event breaking the chain of causation which would otherwise begin with the failure to warn of that risk: "It is contrary to common sense to treat part of the very risk which called the duty into existence as a supervening event breaking the chain of causation beginning with the breach of that duty". Her Honour added that the question could also be answered by asking what would have happened if Dr Chappel had provided Mrs Hart with adequate information: "If he had, Mrs Hart would not then have undergone surgery and would not then have suffered the injuries which she did or their consequences. Thus, Dr Chappel's breach was 'still operating', or, continued to be causally significant when [those injuries were sustained]" (internal quotation marks omitted).
90Gummow J emphasised (at [67]-[68]) that "the very risk of which she should have been warned materialised"; that it was conceded that if the surgery had been performed at a different time, then in all likelihood Mrs Hart would not have suffered the random chance of injury; that the particular risk had been the subject of specific inquiry by Mrs Hart, for whom that risk was more significant than statistical; and that the injury occurred within an area of foreseeable risk. His Honour observed (at [78]) that if Dr Chappel had given Mrs Hart the requisite warning, she would not have undergone that procedure at his hands, but would have wanted the most experienced surgeon in the field, and (at [79]) that had she done so the cumulative risks that produced her injuries were so unlikely to occur as to be speculative.
91Kirby J also accepted that had Mrs Hart been properly warned, the overwhelming likelihood was that she would not in fact have been injured, and added (at [96]):
It is true to say that the inherent risks of injury from rare and random causes arise in every surgical procedure. A patient, duly warned about such risks, must accept them and their consequences. Mrs Hart was ready to accept any general risks of the operation of which she was warned. However, she declined to bear the risks about which she questioned the surgeon and received no adequate response. When those risks so quickly eventuated, commonsense suggests that something more than mere coincidence or irrelevant cause has intervened. This impression is reinforced once it is accepted that Mrs Hart, if warned, would not have undergone the operation when she did.
92That passage emphasises the relationship between the requisite warning and the acceptance of risk by the patient, and identifies a causative link where a risk of which the patient was not warned (and would not have accepted) materialises. His Honour also observed (at [97]) that there would have been a reduced risk with a more experienced surgeon, such as Mrs Hart had said she would have sought out if properly advised.
93Because it preceded the Civil Liability Act, the reasoning in Chappel v Hart is not clearly segregated into consideration of "factual causation" and "scope of liability". However, the reasoning that if properly warned Mrs Hart would have undergone surgery on a different occasion and in all probability not been harmed, and that the relevant harm was actual physical harm not exposure to the risk of it, relates to factual causation (and is consistent with the approach I have adopted to factual causation in this case, above). The predominant reasoning relevant to "scope of liability" was that the risk that materialised and harmed Mrs Hart was the very risk that called the relevant duty to warn into existence - a risk of which she should have been but was not warned, and if warned would not have accepted, at least on the occasion on which it materialised. While Gaudron J (at [18]), Gummow J (at [79]) and Kirby J (at [98]-[99]) also referred to Mrs Hart's evidence that, if she had received the warning that Dr Chappel was obliged to provide to her, she would have retained the most experienced surgeon in the field to undertake the surgery, thereby lessening the risks of surgery, this was not essential to their Honour's conclusions.
94In Chester v Afshar, the plaintiff had severe back pain for which she required neurosurgery, which carried a 1-2% risk of the cauda equina syndrome, of which she was not warned. She proceeded with the surgery, and suffered the complication of cauda equina syndrome. The evidence established that cauda equina syndrome was a random and inherent risk of the surgery, which would have been the same whenever and at whoever's hand she had the operation. It was also established that she would have had the operation at some point in time, regardless of whether she was warned of the risk. The House of Lords (Lords Steyn, Hope and Walker; Lords Bingham and Hoffman dissenting) held that the plaintiff had established causation. The "but for" test was satisfied, because she would not have had the operation when she had it if the appropriate warning had been given and on the probabilities the complication would not have arisen on another occasion (at [19] (Lord Steyn), [81] (Lord Hope), [96], [98], (Lord Walker)). However, because there was no finding that, properly warned, the plaintiff would never have undergone the operation with the same risk, the defendant's failure to warn neither affected the risk nor was the effective cause of the injury so that, on conventional principles, the test of causation was not satisfied ([22]-[23] (Lord Steyn), [60]-[61], [81] (Lord Hope), [90] (Lord Walker)). Nonetheless, the appeal was dismissed, essentially on policy grounds (analogous to s 5D(2)). Lord Steyn (at [14]-[18]) referred to the nature of the correlative rights and duties of the patient and surgeon, the importance of a patient's right to an appropriate warning, and the obligation of a doctor to abstain from performing an operation without consent - which both served to avoid the occurrence of injuries the risk of which a patient was not prepared to accept, and ensured that due respect was given to the autonomy and dignity of each patient; his Lordship concluded (at [24]) that the plaintiff could not be said to have given informed consent to the surgery in the full legal sense, which justified a departure from conventional principles of causation. This reasoning treats the materialisation of a risk of which the plaintiff had not but should have been warned as outside the scope of what the plaintiff had accepted in submitting to surgery, and therefore causally connected to the negligent failure to warn of it.
95Lord Hope of Craighead said:
[87] To leave the patient who would find the decision difficult without a remedy, as the normal approach to causation would indicate, would render the duty useless in the cases where it may be needed most. This would discriminate against those who cannot honestly say that they would have declined the operation once and for all if they had been warned. I would find that result unacceptable. The function of the law is to enable rights to be vindicated and to provide remedies when duties have been breached. Unless this is done the duty is a hollow one, stripped of all practical force and avoidable content. It will have lost its ability to protect the patient and thus to fulfil the only purpose which brought it into existence. On policy grounds I would therefore hold that the test of causation is satisfied in this case. The injury was intimately involved with the duty to warn. The duty was owed by the doctor who performed the surgery that Miss Chester consented to. It was the product of the very risk that she should have been warned about when she gave her consent. So I would hold that in can be regarded as having been caused, in the legal sense, by the breach of that duty.
[88] ... I would hold that justice requires that Miss Chester be afforded the remedy which she seeks, as the injury which she suffered at the hands of Mr Afshar was within the scope of the very risk which he should have warned her about when he was obtaining her consent to the operation which resulted in that injury.
96Again, his Lordship's reasoning relies on the relationship between the risk that materialised and the duty to warn of it, and between the duty to warn and the patient's consent.
97Lord Walker also stressed the connection between the duty to warn and the need for consent:
[93] The surgeon's duty to advise and warn his patient is closely connected with the need for the patient's consent to submit, under anaesthesia, to invasive surgery which would (in the absence of consent) be an assault. The advice is the foundation of the consent. That is why it is so important. ... In this case the surgeon failed to warn of the risk of the very calamity which occurred in the course of the operation which he performed three days later.
98His Lordship referred to the passage cited above from Kirby J's judgment in Chappel v Hart, and concluded:
[101] Nevertheless there are real difficulties (especially, perhaps, for a conscientious claimant aware of the fallibility of hindsight) in a claimant asserting that (if warned of the risks) she would never in any circumstances have submitted to surgery. There would be a danger, as Lord Hope points out, of an honest claimant finding herself without a remedy in circumstances where the surgeon has failed in his professional duty, and the claimant has suffered injury directly within the scope and focus of that duty. I agree with Lord Steyn and Lord Hope that such a claimant ought not to be without a remedy ...
99Chappel v Hart and Chester v Afshar share the features that they are failure to warn cases, in which the relevant damage was the materialisation of the very risk that called into existence the duty to warn of it, and that a proper warning would have resulted in the patient not accepting that risk, at least on the occasion and at the hands of the surgeon in question - a choice of which the breach of duty deprived the patient, so that the relevant risk was outside the scope of the risk that the patient had accepted in submitting to surgery. The speeches of the law Lords - and the judgment of Kirby J in Chappel v Hart - emphasise the relationship between the requirement for consent and the duty to warn. Essentially, while the absence of "fully informed consent" in this sense does not vitiate consent so that the surgery amounts to an assault, its deficiency means that the patient has involuntarily been exposed to a risk which she would not have accepted then and there if properly warned, and which materialised. The rationale of these cases is that the risk that materialised was one to which the patient was exposed - although she was not prepared to accept it - because of the negligent failure to warn. In other words, because of the failure to warn, the patient suffered harm at the hands of the surgeon outside the scope of the risk that she was prepared to accept and to which - for the purposes of the law of negligence, though not that of trespass - her less than fully informed consent did not extend. In such circumstances, the law regards the materialisation of the relevant risk that should have been the subject of a warning and which the patient so warned would not then have accepted, as causally connected to the failure to warn. This reflects that the duty to warn serves to protect the patient from harm from material inherent risks that are unacceptable, by enabling the patient to make an informed choice as to whether to undergo the procedure at all, or on the occasion and at the hands of the surgeon in question.
100These considerations are not applicable to the duty to use reasonable care in and about diagnosis, which serves a different purpose - to protect the patient from harm from an ongoing or deteriorating illness of injury, by enabling its timely treatment. The purpose of diagnosis is to enable appropriate treatment, not to enable the patient to give fully informed consent to it; the information diagnosis provides is of the conditions from which the patient suffers that may require treatment and from which the plaintiff may suffer harm if not treated, not of inherent risks associated with the proposed treatment in order fully to inform a patient's decision whether or not to proceed. The risk that calls into existence the duty to diagnose is the risk of ongoing or deteriorating illness or injury if not treated - not the risks associated with treatment, to which diagnosis is a precursor. And there is no difficulty in a patient who suffers harm as a result of negligence in diagnosis recovering damages on normal principles of causation: if a patient suffers harm from the continuation or deterioration of an illness or injury that would have been avoided by treatment consequent on careful diagnosis, that harm will be within the scope of liability.
101Applied to the present facts, it was the risk of spontaneous rupture (which did not eventuate), as distinct from that of intra-procedural rupture, that called into existence the duty to make a timely and accurate diagnosis. The duty was to exercise reasonable care in reporting on the CT scans, so as to enable treating doctors to recommend appropriate treatment for Mrs Paul's condition. Dr Cooke had no duty to warn the plaintiff about, nor any other responsibility for, inherent risks of any treatment that might follow from making a proper diagnosis. If the aneurysm had spontaneously ruptured causing harm during the two-and-a-half year period in which it remained undiagnosed, when otherwise it would have been treated, then Dr Cooke would have been responsible: the delay in diagnosis would have made a real contribution to the harm. And if delay in diagnosis had increased the difficulty or risks of treatment by the time the diagnosis was belatedly made, Dr Cooke may well also have been liable. But there is no evidence of that here (there was a slight suggestion that there was an increased morbidity risk with age, but no evidence that this was material in the context of Mrs Paul being 2.5 years older; in any event, that must be offset against improvements in operative techniques and procedures over the same period).
102The Plaintiff submitted that Mrs Paul underwent a specific investigation, akin to the specific inquiry made by Mrs Hart in Chappel v Hart about the risks of surgery, to determine whether she had an aneurysm; that given what had happened to her twin sister, the potential consequences of having an aneurysm were all the more significant for her; and that, as the central concern of Mrs Hart in Chappel was obtaining adequate advice about the risks of surgery, so in this case the central concern of Mrs Paul was in finding out whether she had an aneurysm of the type that led to the tragic, early death of her twin sister, so that she could have treatment that would avert those consequences. So much can be accepted. But the consequences that Mrs Paul sought to avoid were those of spontaneous rupture; whereas the risk of intra-procedural rupture was inherent in either course of treatment that she might have chosen upon being diagnosed at any time. Treatment in which that risk was inherent was a consequence of the diagnosis, whenever it was made - not of failure to make a diagnosis. The risk that materialised was not the risk that founded the duty, but a risk associated with fulfilment of the duty, whenever it was fulfilled, by the making of a diagnosis.