High Court dismisses appeal in Wallace v Kam - Patient's claim unable to satisfy two limb causation test
Insurance eBulletin - 9 May 2013
The High Court has unanimously dismissed the appeal of a patient in a failure to warn claim against a surgeon. The surgeon had negligently failed to warn the patient of two distinct inherent risks of a procedure. The patient would have gone ahead with the procedure had he been warned of the risk which materialised and caused harm, but would not have gone ahead had he known of the other risk.
The High Court ruled that while this scenario may satisfy the first limb of causation in negligence, factual causation, it did not satisfy the second limb, scope of liability. This was because the Court considered it would not be appropriate to hold the surgeon liable for the consequences of an acceptable risk on the basis of negligence associated with an unacceptable risk which never eventuated.
Although a medical practitioner’s duty to warn is bound up with notions of informed consent, the policy which underlies that duty is not to protect a patient's right to choose, nor to protect them from exposure to all unacceptable risks. Rather, the policy is to protect a patient from injury, the risk of which is unacceptable to them. Where the injury they sustain is not the result of such risk, there can be no liability.
- Causation in negligence
- Wallace v Kam - facts
- Court of Appeal
- High Court
- Implications for insurers
- Further information
Medical practitioners have a duty to their patients to exercise reasonable care and skill in the provision of professional advice and treatment. This duty usually carries with it a requirement to warn a patient of material risks of injury inherent in any treatment they propose. A risk is considered material if it is one to which a reasonable person in the patient's position is likely to attach significance, or one that the medical practitioner knows, or ought reasonably know, the particular patient is likely to attach significance in choosing whether or not to undergo treatment.
The reason for imposing a duty to warn is so that a patient can make an informed choice about whether to have treatment and to avoid the occurrence of a particular physical injury, the risk of which is unacceptable to them.
While the duty is bound up with notions of informed consent, the policy behind it is not to protect a patient's right to choose, nor to protect them from exposure to all unacceptable risks. Rather, it is to protect a patient from injury, the risk of which is unacceptable to them.
In establishing a defendant’s liability to pay damages in negligence, a plaintiff must prove that the defendant owed them a duty of care, that the duty was breached and that the breach caused the damage.
All Australian states and the Australian Capital Territory have a statutory test for determining causation in negligence claims. Wordings may differ, but the test essentially involves two limbs: factual causation and scope of liability, both of which must be satisfied before causation is established.
The provision governing causation in Wallace v Kam1 was s 5D of the Civil Liability Act 2002 (NSW). It provides:
(1) A determination that negligence caused particular harm comprises the following elements:
(a) that the negligence was a necessary condition of the occurrence of the harm (factual causation), and
(b) that it is appropriate for the scope of the negligent person's liability to extend to the harm so caused (scope of liability).
(2) In determining in an exceptional case, in accordance with established principles, whether negligence that cannot be established as a necessary condition of the occurrence of harm should be accepted as establishing factual causation, the court is to consider (amongst other relevant things) whether or not and why responsibility for the harm should be imposed on the negligent party.
(3) If it is relevant to the determination of factual causation to determine what the person who suffered harm would have done if the negligent person had not been negligent:
(a) the matter is to be determined subjectively in the light of all relevant circumstances, subject to paragraph (b), and
(b) any statement made by the person after suffering the harm about what he or she would have done is inadmissible except to the extent (if any) that the statement is against his or her interest.
(4) For the purpose of determining the scope of liability, the court is to consider (amongst other relevant things) whether or not and why responsibility for the harm should be imposed on the negligent party.
It was the scope of liability limb of causation, s 5D(1)(b), which was in issue in Wallace and which lead to a finding that the defendant's negligence in failing to warn his patient of an inherent risk of a surgical procedure which did not come home, should not result in a liability to pay damages for the materialisation of another risk. This was so even where it was accepted that had the surgeon properly warned his patient, the harm would not have occurred because the procedure would have been declined.
The patient underwent surgery to try to alleviate pain in his lower spine caused by a disc protrusion. The surgery was unsuccessful and one of its inherent risks, temporary nerve damage known as bilateral femoral neurapraxia, left the patient in severe pain for some time. The surgeon should have, but did not, warn the patient of this inherent risk and of a 5% risk of permanent catastrophic paralysis, which fortunately did not occur.
The patient sued the surgeon for negligence claiming that had he been warned of these risks, he would not have undergone the surgery and would not therefore have suffered neurapraxia.
The trial judge dismissed the claim on the basis that factual causation had not been established because even if the patient had been warned of the risk of neurapraxia, he would have elected to go ahead with the surgery anyway. As such, the surgeon’s negligent failure to warn was not causative of the patient’s harm.
The patient maintained on appeal that even if he would have accepted the risk of neurapraxia had he been warned, he would not have gone ahead with the procedure if he knew of the additional catastrophic risk of paralysis. Since the trial judge had made no finding on this subject, the Court of Appeal proceeded on the assumption that a warning of the risk of paralysis would have meant that the patient would indeed have declined the surgery. Factual causation was therefore established.
The Court of Appeal split 2:1 on whether the second limb of causation, scope of liability, was made out. The majority considered that it was not appropriate to hold the surgeon liable for the patient’s neurapraxia on the basis of negligence relating to a separate risk, paralysis, which did not materialise.
The High Court agreed with the majority of the Court of Appeal’s view and unanimously dismissed the appeal.
The Court made the following points about how s 5D, and causation provisions like it, operate in a negligence claim:
A determination in accordance with s 5D(1)(a) that negligence was a necessary condition of the occurrence of harm is entirely factual and turns on proof by the plaintiff of relevant facts on the balance of probabilities. It is simply a “but for” test.
A determination in accordance with s 5D(1)(b) that it is appropriate for the scope of the negligent person's liability to extend to the harm so caused is entirely normative and turns on consideration by a court of (amongst other relevant things) whether or not, and if so why, responsibility for the harm should be imposed on the negligent party in accordance with s 5D(4).
Both limbs of s 5D(1) must be established in order for there to be a finding of legal causation in a negligence claim.
Factual causation will not be established in a failure to warn case if a patient would have chosen to undergo treatment even if they had been warned of all material risks, because “but for” the failure to warn, the treatment would still have gone ahead when it did and the injury would still have been sustained. Leaving aside the possibility of an exceptional case to which s 5D(2) might apply, as s 5D(1)(a) is not satisfied, there is no need to consider the normative question posed by s 5D(1)(b).
Factual causation will be established in a failure to warn case if a medical practitioner breaches their duty to warn a patient of one or more material risks inherent in a proposed treatment, and the patient proves that they sustained, as a consequence of having chosen to undergo the treatment, physical injury which would not have been sustained if they had been warned of all material risks. As this necessarily turns on a determination of what the patient would have chosen to do, s 5D(3) comes into play and the issue of what the plaintiff would have done is to be determined subjectively in the light of all relevant circumstances, however the patient’s own evidence about what he or she would have done is inadmissible unless it is against their interest.
The situation is less clear in a case where a patient, if warned of material risks, would have chosen not to undergo the treatment at the time it in fact took place, but chooses to undergo the treatment at a later date. In the High Court’s view, factual causation is made out because, absent the negligent failure to warn, the treatment that in fact occurred would not have occurred when it did and the physical injury in fact sustained would not then have been sustained.
If a case falls within an established class, the normative question posed by s 5D(1)(b) is answered by a court through the application of precedent. This means that a policy choice made in relation to the established class will be maintained in a subsequent case falling within that class unless confronted and overruled.
In a novel case, s 5D(4) requires a court, when answering the normative question posed by s 5D(1)(b), to explicitly consider and explain in terms of legal policy whether or not, and why, responsibility for the harm should be imposed on the negligent party. A court must identify and articulate an evaluative judgment by reference to the purposes and policy of the relevant duty of care.
Factual causation was made out in Wallace because of the assumption that a warning given to the plaintiff of the risk of paralysis would have resulted in him declining the surgery. But for that negligent failure to warn, the surgery would not have gone ahead and the harm, the neurapraxia, would not have occurred.
In arriving at its conclusion that scope of liability was not, however, established, the High Court considered the policy behind the imposition of a duty to warn on a medical practitioner.
In its view, while the duty is bound up with notions of informed consent, the policy which underlies it is not protection of a patient's right to choose, nor is it to protect a patient from exposure to all unacceptable risks. Rather, in the Court’s view, the policy is to protect a patient from injury, the risk of which is unacceptable to them. Where the injury actually sustained is not the result of such risk, there can be no liability.
The patient’s injury, the neurapraxia, was the result of the materialisation of a risk which he was prepared to accept. It was this injury for which the patient wished to make the surgeon liable. The Court was simply not prepared, on normative grounds, to sheet such liability home on the basis of negligence which related to an entirely separate risk of injury which did not materialise.
This is a welcome decision for all liability insurers in that it emphasises the quite distinct division between the two limbs of causation which are often muddied by courts. While scope of liability and its normative requirements are relevant in any negligence claim to which the various civil liability statutes apply, it is more likely to feature in medical negligence claims where there can be a number of factors which, at least in a factual sense, result in harm.
Treatments can hold a number of inherent risks which, if warned of, may well dissuade a patient from agreeing to undergo them. This decision will at least require a court to focus on the particular risk which eventuated and confine itself to considering a defendant’s liability based on negligence associated with that risk, not other risks of the procedure which did not eventuate.
This is not to say that the cumulative effect of a number of risks of a procedure can never result in a finding of liability. As the High Court pointed out, if the risks essentially build on one another so that they increase the likelihood of at least one of their number materialising, a failure to warn of one of those risks, while warning the patient of another, may constitute a failure to warn of the extent, or likelihood of a risk and therefore expose the patient to a level of risk of injury occurring which is unacceptable to them.
Kate Clark | Special Counsel
1  HCA 19
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