The legal uncertainty that arose after the 2004 New South Wales Court of Appeal decision in Rufo v Hosking has ended. In an unanimous decision, the High Court of Australia has held in Tabet v Gett that damages are not available for the loss of a chance of a better medical outcome unless the plaintiff can prove, on the balance of probabilities, that he or she would have had a better outcome had the defendant not been negligent.
The case concerned the medical treatment of a six year old girl named Reema Tabet. Reema was admitted to hospital in 1991 after recovering from chickenpox. She was suffering headaches and nausea, and was vomiting. She came under the care of Dr Maurice Gett, a paediatrician. Dr Gett made a provisional diagnosis of post-chickenpox viral encephalitis.
Unfortunately, Reema later suffered a rapid deterioration in her neurological condition and had a seizure. A CT scan revealed a brain tumour. Reema underwent surgery to remove part of the tumour. She was subsequently diagnosed as having suffered irreversible brain damage. The damage had a number of causes. It was partly sustained when her condition had deteriorated. It was partly caused by the tumour itself (which had been growing for over two years). It was also partly a result of her operation and other treatment she had received to control the tumour.
The expert evidence that Reema adduced at trial supported a finding that Dr Gett should have arranged for her to have a CT scan before her condition had deteriorated. The evidence also supported a finding that, if Reema had had an earlier CT scan (and the tumour been revealed), treatment options were available to her that may have avoided the deterioration in her condition. The trial judge did not think Reema had proved on the balance of probabilities that she would not have suffered the brain damage if she had undergone the treatments. Despite this finding, however, applying the reasoning in Rufo v Hosking, the trial judge found that it was probable that Reema's decline contributed to her ultimate disabilities and assessed that contribution to be no greater than 25% of her damage. He then assessed that her loss of a chance of a better outcome (ie avoiding the damage which was referable to the deterioration) was 40%. The trial judge therefore found that Reema was entitled to 40% of 25% of the damages to which she would have been entitled if all of her brain damage was caused by Dr Gett's negligence.
Dr Gett appealed to the Court of Appeal. He argued that Reema had not proved on the balance of probabilities that she had suffered any brain damage as a result of not having had an earlier CT scan and the treatments she alleged she would have received.
After reviewing the expert evidence, the Court of Appeal held that Reema's loss of a chance of a better outcome ranged between 'speculative' and 'some'. It ultimately settled on a finding that Reema had lost only a 15% chance (as opposed to the trial judge's 40%) of avoiding the brain damage she complained of. This being the case, the Court of Appeal concluded that Reema had not proven on the balance of probabilities that she had suffered any brain damage as a result of Dr Gett's breach of duty to her.
Reema subsequently appealed to the High Court of Australia.
In the High Court
The question at the centre of Reema's appeal was whether the common law of Australia should recognise that the loss of a chance of a better medical outcome is actionable in damages. After considering the central question, the development of the common law in other countries and the expert evidence led at trial, Acting Chief Justice Gummow and Justices Hayne, Bell, Crennan and Kiefel all answered in the negative and dismissed Reema's appeal, providing separate reasons for their decision.
Redefining damage and causation
All five judges held that the adoption of the 'loss of a chance' as a basis for liability in personal injury cases would represent a major development in the common law. Their Honours observed that, if Reema's arguments were accepted, Dr Gett would be held liable even though what Reema had lost was only the possibility, not probability, that her brain damage would have been less serious than it was. This would shift the balance the law of negligence had previously created between the competing interests of plaintiffs and defendants and tip it in favour of plaintiffs. Their Honours did not consider there was any reason why the law should allow a reduced requirement for proving causation so that a plaintiff should have the benefit, and the defendant the detriment, of an easier burden of proof of actionable damage in negligence actions.
Applicable policy reasons
Justice Gummow noted that there was possibly a view, especially with respect to medical treatment, that the substitution of loss of a chance as an actionable damage instead of physical damage would assist in the maintenance of medical standards in circumstances where there was a less than 50% chance of a cure. However, he said that any such potential benefit to the public had to be weighed against, for example, the prospect of 'defensive medicine' being practised, with an emphasis on costly testing procedures in preference to a sequential deductive approach to diagnosis and treatment. Justice Crennan similarly found that policy considerations - including the prospect of encouraging defensive medicine, the impact of that on the Medicare system and private medical insurance schemes, and the potential increase in the cost of medical malpractice insurance - weighed against altering the present requirement of proof of causation in cases of medical negligence. Her Honour said that the change to the law that Reema proposed was so radical that it was the business of Parliament, not the common law.
Justice Kiefel acknowledged that Reema had suffered a dreadful injury, but similarly thought that her case did not provide a strong ground for changing the law. Her Honour said the change Reema was arguing for would paradoxically result in Dr Gett being held liable for damage which he almost certainly did not cause.
Had Reema proved she lost a chance anyway?
Justice Heydon also dismissed Reema's appeal. However, his Honour did so because there was no evidence to support a finding as to the percentage chance that Reema's brain damage could have been avoided. His Honour noted that the difference between Reema's percentage chance as found by the trial judge (a 40% chance of a better outcome) and the Court of Appeal (a 15% chance of a better outcome) showed that, in truth, the expert evidence led at trial did not enable the court to reach any conclusion as to whether Dr Gett's negligence had caused Reema to lose a chance of avoiding or reducing her brain damage. In the circumstances, Justice Heydon considered the central question before the High Court was not even a live issue because it assumed that the evidence supported some finding about the chance that Reema had lost. His Honour therefore did not consider it was necessary or desirable to embark on 'difficult and doubtful inquiries' in an attempt to answer it.
The High Court's decision is consistent with the reasoning in Amaca Pty Ltd v Ellis, The State of South Australia v Ellis and Millennium Inorganic Chemicals Ltd v Ellis and re-affirms that the applicable (and only) standard of proof in negligence actions is the balance of probabilities.
Loss of chance claims in medical negligence litigation appear now to be a thing of the past. Plaintiffs should now only be awarded damages for the loss of a proven better outcome, not a percentage of that loss based on the probability (or improbability) of the outcome occurring. This stabilisation of the law will be of comfort not only to medical indemnity insurers, but also to the medical profession working in an already financially-strained healthcare system, which has limited capacity to manage 'defensive medicine'.
 (2004) 61 NSWLR 678
  HCA 12125
  HCA 5 decided on 3 March 2010
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