Australia: A medical practitioner's duty to warn and causation

Curwoods Case Note
Last Updated: 24 April 2012
Article by Yasmin Bell

Judgment date: 13 April 2012

Wallace v Kam [2012] NSWCA

NSW Court of Appeal1

In Brief

  • A medical practitioner has a duty to warn a patient of all material risks inherent in the proposed treatment.
  • In order to establish negligence the Court must be satisfied that the failure to warn was the cause of the harm.
  • In order to establish whether a medical practitioner's failure to warn was causative of a patient's injury, the Court will consider the test for causation set out in s 5D of the Civil Liability Act 2002 (CLA).
  • Although a patient has only one decision to make as to whether to have an operation, when there is more than one material risk to an operation, each risk can be seen as separate and distinct.
  • The failure to warn of a particular risk that would have prevented the patient from undergoing surgery but did not occur, will not necessarily result in a finding of negligence in relation to another harm where the risk did not occur.
  • A medical practitioner does not bear the responsibility for a breach of duty to warn of a risk that did not materialise, even if the warning would stop the patient from having the surgery and the patient suffered some other form of harm as a result of the surgery.


In November 2004 the plaintiff, Mr Wallace, underwent surgery to alleviate pain in his lumbar spine. The surgery was performed by the defendant, Dr Kam, a Neurosurgeon at Westmead Private Hospital. Following the surgery, the plaintiff continued to suffer pain and was subsequently diagnosed as having suffered bilateral femoral neuropraxia, being local nerve damage to the thigh region of both legs. This was caused by lying prone for an extended period during surgery.

The plaintiff commenced proceedings against the defendant for breach of duty in failing to warn of the material risks of the surgery. There were 2 material risks that were not disclosed, namely:

  1. Risk of local nerve damage to the thigh (bilateral femoral neuropraxia).
  2. A 5% risk of paralysis (a catastrophic outcome).

The second risk arose because the site of the operation was in the spinal cord and there was an inherent risk of injury to the spinal nerves.

The CLA provides that the question of causation in relation to negligence has to be determined on the basis of the provisions of s 5D, which relevantly 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 principals, 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."

Supreme Court Decision

The trial judge, Harrison J, identified the following issues for determination:

  1. Whether the defendant breached his duty of care to the plaintiff by failing to give a proper warning of the risk of the surgery performed (the breach issue).
  2. Whether the plaintiff suffered harm in the circumstances (the injury issue).
  3. If harm was suffered, whether the harm was caused by the defendant's negligence (the causation issue).

His Honour held that the defendant breached his duty of care to the plaintiff by failing to warn of the material risks of bilateral femoral neuropraxia and that the plaintiff suffered an injury as a result of the surgery. However his Honour was not satisfied that the plaintiff would have declined the surgery had he been warned of the risk. He therefore concluded that the plaintiff failed to establish any causal connection between the defendant's breach of duty and injury.

Relevantly, his Honour did not make any findings of whether the risk of paralysis was a material risk which the defendant was under a duty to disclose to the plaintiff, nor whether the plaintiff would have declined the operation if warned of that risk. Importantly, his Honour held that the failure to warn of bilateral femoral neuropraxia was the only potential relevant failure to warn and that the plaintiff's allegation that the defendant had failed to warn him of possible catastrophic consequences was not relevant, because that risk had not eventuated.

Court of Appeal Decision

The plaintiff appealed against his Honour's judgment. The issue for determination on appeal was whether the trial judge erred in confining the relevant breach of duty to the failure to warn of the risk of bilateral femoral neuropraxia.

The plaintiff contended that:

  1. The scope and content of the defendant's duty was to adequately warn the plaintiff of all material risks of the operation, that duty being a "single comprehensive duty".
  2. The defendant had breached his duty not only by failing to warn of the risk of bilateral femoral neuropraxia, but also by failing to warn of the 5% risk of a catastrophic outcome.
  3. It followed that the causation issue had to be determined having regard to the entire breach.
  4. The plaintiff would have deferred or refused this surgery had he been warned of the risk of a catastrophic outcome.

All judges had regard to the decision of Rogers v Whittaker 2where the court stated:

"The duty of a medical practitioner to exercise reasonable care and skill in the provision of professional advice and treatment is a single comprehensive duty" 3.

All judges also considered the decision of Rosenberg v Percival 4 (Rosenberg) where Gummow J, in assessing causation in relation to a duty to warn, found that a medical practitioner would not be held liable for a failure to warn a patient of a material risk of damage to her laryngeal nerve, if the injury that eventuated resulted from a misapplication of anaesthetic. His Honour held that this would be so despite the fact that the plaintiff would have not had the treatment and therefore would not have suffered the injury from the misapplication of anaesthetic if the patient had been warned of the risk to her laryngeal nerve. His Honour noted that this would be an example of whether the application of the "but for" test would lead to an unacceptable result.

The court delivered 3 separate judgments, with Allsop P and Basten JA dismissing the appeal and Beazley JA dissenting.

Allsop P (Basten JA agreeing in part)

Allsop P held that the task involved in assessing causation pursuant to s 5D(1)(a) of the CLA will depend upon a factual enquiry.

In this case, his Honour noted that one operation was being contemplated and the potential benefits and risk of undergoing that operation were all part of the relevant information, as a whole, which the plaintiff was entitled to have in order to make up his mind. He considered that the duty was one comprehensive duty.

His Honour then turned to the operation of s 5D(1)(b) to assess whether it was "appropriate for the scope of the negligent person's liability to extend to the harm so caused". He considered that the enquiry involved a value judgment noting that there needed to be an appropriate causal relationship between the breach and the harm. His Honour noted that certain circumstances exist where it is not appropriate to extend the scope of liability, even though the "but for" test was satisfied.

With regard to a duty to warn, he considered that in certain circumstances it would not be possible to disentangle one risk from another. However, in other circumstances, risks may be seen as separate and distinct when they have no other relevant medical relationship or connection.

His Honour concluded that the risk of neuropraxia and the 5% risk of catastrophic paralysis should be seen as distinct matters for disclosure. The 2 risks were not said to be related in any way. He therefore concluded that the failure to warn of the risk of paralysis was not causative of the plaintiff's injuries and that the appeal should be dismissed.

Basten JA

Basten JA relied on the following statement of Gummow J from Rosenberg:

"If the medical practitioner should fail to warn the patient of a particular consequence and that consequence in fact eventuates, subject to the question of materiality, the rule seeks to hold the medical practitioner liable for that consequence." 5

His Honour considered that the reference to warning of "a particular consequence", followed by the condition that "that consequence in fact eventuates" is not ambiguous. Nor is it to be dismissed as incautious or inaccurate use of the language.

His Honour held that although a patient has only one decision to make regarding whether to undertake an operation or not, the factors to be placed into the balance in making that decision are separate and each with its own weight.

His Honour noted that the 2 risks in question were not closely associated. The catastrophic risk of paralysis was connected to the skill and care exercised by the surgeon in carrying out the operation. By contrast, the bilateral femoral neuropraxia arose from the fact that the plaintiff was required to lie on his front for a significant period.

His Honour considered that the distinction between the 2 risks was not far removed from the example supplied by Gummow J above, being the possible injury to the laryngeal nerve and the risk of misapplication of the anaesthetic.

His Honour held that a medical practitioner should not bear the responsibility for a breach of a duty to warn of a risk that did not materialise. Recovery in such circumstances would be opportunistic.

His Honour therefore agreed with the trial judge that negligence had not been established.

Beazley JA (dissenting)

Beazley JA held that where there is more than one material risk to an operation and a finding is made that a plaintiff would not have undergone surgery if warned of other material risks, it is difficult to see reasons why a negligent doctor should not be liable notwithstanding that a different risk eventuated.

He considered that in this case, the failure to warn of paralysis was a material risk with very serious consequences and with a relatively high risk of occurrence. He held that if it were to be found that a plaintiff would not have undergone surgery if warned of this risk, then it is appropriate that the scope of the defendant's liability extend to the harm in fact caused.

He considered that a failure to warn of more than one material risk is different from the example of the harm suffered whilst a patient was under an anaesthetic, to which Gummow J referred in Rosenberg. In his opinion, it might be arguable that such a circumstance constituted a novus actus.

His Honour held that, in this case, the connection between the scope of duty and what the plaintiff would have done if there had been no breach were sufficiently connected for it to be appropriate for the scope to extend to the harm in fact suffered. He considered that the trial judge erred in finding that the only potentially relevant risk was the bilateral femoral neuropraxia.


The decision reinforces the principle in Rogers v Whittaker that a doctor has a duty to warn a patient of all material risks involved in a particular procedure.

The decision highlights that, to establish negligence, there must be a causal relationship with the outcome sufficient to warrant imposing on the medical practitioner responsibility for the harm.

In certain instances, risks associated with treatment can be seen as separate and distinct. In such circumstances recovery is limited to risks:

  1. that eventuate;
  2. that were material;
  3. that should have been disclosed; and
  4. that were not acceptable to the patient.

The decision indicates that, in assessing causation in relation to a medical practitioner's duty to warn, it is not necessarily sufficient that the harm suffered was within the area of foreseeable harm, and that the patient would not have had the operation if warned of a material risk that did not occur. In determining causation, the relevant risk to assess is the risk that in fact eventuated.

The statutory elements of causation found in s 5D of the CLA have not abrogated the necessary connection between duty of care, its nature and scope and causation.


1 Allsop P, Beazley and Basten JJA
2 (1992) 175 CLR 479
3 at 439 per Mason CJ, Brennan, Dawson, Toohey and McHugh JJ
4 (2001) 205 CLR 434
5 at 461

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