ON 2 SEPTEMBER 1998, the High Court of Australia delivered Chappel v Hart  HCA 55; 195 CLR 232; 156 ALR 517; 72 ALJR 1344 (2 September 1998).
A procedure to repair a perforation of the oesophagus carried a small inherent risk of infection which could damage the plaintiff’s laryngeal nerve and voice. The patient, who suffered an infection, was not warned of these risks. It was found that had the patient been informed of the risks he would have deferred the procedure and had it performed by a more experienced surgeon.
Using the “common sense” test of causation of March v Stramare (E & M H) Pty Ltd, the High Court held that the patient’s harm was caused by the doctor’s failure to warn of risk rather than a failure with the actual care provided.
The court applied a subjective approach for determining what the patient done had the doctor not been negligent in failing to warn him of the risk.
Per Gaudron J at :
“Furthermore, a defendant is not causally liable, and therefore legally responsible, for wrongful acts or omissions if those acts or omissions would not have caused the plaintiff to alter his or her course of action. Australian law has adopted a subjective theory of causation in determining whether the failure to warn would have avoided the injury suffered. The enquiry as to what the plaintiff would have done if warned is necessarily hypothetical. But if the evidence suggests that the acts of omissions of the defendant would have made no difference to the plaintiff’s course of action, the defendant has not caused the harm which the plaintiff has suffered.”
Per McHugh J at :
“The question of causation is not resolved by philosophical or scientific theories of causation”
The Civil Liability Act 2002 has modified the common law position with regards to the common sense test and subjective approach to causation.
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