The demise of loss of a chance cases in medical negligence claims

In January 1991 the respondent paediatrician, in the presence of a history of headaches, vomiting and chicken pox rash, diagnosed Ms Tabet with post chickenpox viral encephalitis. Two days later, she suffered a seizure. The following day, after a rapid deterioration in her neurological state, a CT scan revealed the presence of a brain tumour. She subsequently underwent partial removal of the tumour, chemotherapy and radiotherapy, but suffered irreversible brain damage.

Ms Tabet alleged a CT scan should have been performed on either 11 or 13 January 1991, which would have revealed the brain tumour, leading to earlier and different treatment. She alleged the delay and diagnosis either caused or contributed to the seizure and subsequent deterioration on 14 January, leading to irreversible brain damage, or that she lost a chance of a better medical outcome from the delay in diagnosis.

The trial judge, Studdert J found the paediatrician negligent for failing to order a CT scan on 13 January 1991. He found that the delayed tumour diagnosis was neither the cause nor a material contributor to her brain damage (i.e. a greater than 50% contributor), but rather deprived her of a 40% chance of avoiding the 25% of her brain damage which arose out of her seizure. Where he assessed Ms Tabet’s damages resulting from the entirety of the brain injury as being $6,092,586, she was entitled to $610,000 (i.e. 40% of 25% of the full sum).[1]

The paediatrician appealed to the NSW Court of Appeal challenging (among other things) the entitlement to recover damages for loss of a chance. The Court (Allsop P, Beazley and Basten JJA) upheld his appeal, denying recovery for loss of a chance and describing the approach of allowing damages to reflect a lost chance as being “plainly wrong”.[2]   In a joint judgment it emphasised the need for a plaintiff must demonstrate that a risk of harm arising from a breach of duty was probable, not merely possible, in order to recover damages. The loss of a chance analysis meant the risk of harm arising from a breach of duty was merely possible, not probable. Awarding damages for loss of a chance of a better medical outcome would essentially alter the common law principle of causation by removing the requirement to prove, on the balance of probabilities, the damage was caused by the breach of duty. The Court concluded that the New South Wales case of Rufo v Hosking[3] and the Victorian case of Gavalas v Singh[4] should not be followed as they were “plainly wrong”. The Court was concerned that allowing loss of a chance claims in medical negligence would potentially pose a multitude of consequences lacking certainty and clear parameters. The Court thought that it was only be for the High Court “to reformulate the law of torts” in such a way.[5]

The appeal to the High Court

The High Court (comprised of Gummow ACJ, Hayne, Heydon, Crennan, Kiefel and Bell JJ) unanimously dismissed the appeal, clarifying the position in Australia on cases involving the loss of a chance of a better medical outcome.

Acting Chief Justice Gummow dismissed the appeal on the following bases:

(a) Ms Tabet’s evidence amounted to no more than speculation on whether there was the loss of a chance of a better outcome; and

(b) Personal injury cases alleging negligence do not allow recovery of damages when that damage is a loss of a chance of a better outcome, distinguishing the case from breach of contract cases because of the need to identify damage.

His Honour saw loss of a chance cases as weakening the traditional approach to personal injury cases which struck a balance between competing interests of the parties and that to allow loss of a chance recovery would represent an unwarranted shift in the balance towards claimants.

In their joint judgment Hayne and Bell JJ, agreeing with Kiefel J (see below), dismissed the appeal on the basis that Ms Tabet did not prove breach of duty was a cause of her brain damage. Consistent with Gummow ACJ’s approach, they saw that acceptance of recovery for loss of a chance of a better medical outcome would be an unwarranted shift in the balance between the interests of the claimant and defendant. The language of possibilities (i.e. the notion of “chance”) should not obscure the need to identify whether the possible adverse outcome has in fact occurred.[6] However, they did leave open the possibility of loss of a chance cases in other scenarios (i.e. reduced life expectancy).

Following a detailed analysis of the trial evidence, Heydon J concluded that there was insufficient evidence to identify and quantify any lost chance. Accordingly he did not determine the viability of loss of a chance claims in medical negligence as “the question has become purely abstract and academic”.[7]

In agreeing with Kiefel J, Crennan J thought to accept “loss of a chance” as a basis for liability would represent a fundamental and radical change to the common law and the kind of change which was, generally speaking, the business of parliament, distinguishing such cases from ones involving pure economic loss. [8]

Kiefel J concluded that Ms Tabet’s evidence was insufficient to prove that it was probable that, had treatment been undertaken earlier, the brain damage which occurred on 14 January 1991 would have been avoided.[9] In order for Ms Tabet to succeed, the law of negligence would have to undergo a fundamental change whereby the common law standard of proof was lowered. Other cases, including for loss of commercial opportunities and in similar contexts overseas, were not persuasive or consistent with Australian personal injury law. She thought to allow recovery would lower the standard of proof to possibilities not probabilities.

Implications

Tabet v Gett seems to spell the death knell for most, if not all, loss of a chance cases in medical negligence and other personal injury contexts. However, this is likely to lead to a focus on how to bring these types of cases in new ways, such as by demonstrating how breach of duty was the cause of discrete damage, but not the entire injury (i.e. a psychiatric condition arising out of discovery of a delay in diagnosis or delay in treatment having particular economic implications).

Future cases in what would previously have been seen as loss of a chance contexts may also be argued on the basis that a breach of duty increased a risk of harm which eventuated. Such cases occur where the expert evidence falls short of demonstrating a probable causal link between breach and harm, but where an analysis of the surrounding circumstances (i.e the nature of duty of care owed and breach, degree of increased risk, likelihood of the plaintiff falling within that class of increased risk and absence of other explanations for the injury) supports a causal link.[10] However, Tabet v Gett suggests that any such actions based on breach of duty leading to an increased risk of harm materialising will be closely scrutinised to determine whether it is probable, not merely possible, that the risk eventuated. As seen in asbestos cases, the mere use of statistics will usually be insufficient. There has been a tension in different states, particularly New South Wales and Victoria, towards how high such an evidentiary burden is set in such cases.[11] Tabet v Gett suggests a more stringent and critical evaluation, similar to New South Wales approaches, on whether the risk of harm eventuated.

The analysis of Gummow ACJ, Heydon and Kiefel JJ, finding insufficient evidence to identify and quantify any lost chance, perhaps represents a rejection of the “robust and pragmatic approach” referred to in Rufo v Hosking[12] towards the analysis of medical evidence, particularly on causation issues, in favour of a close analysis of the available evidence. This emphasises the need for careful consideration on whether medical evidence supports or disputes the existence of any relationship between breach of duty and damage. Inference will usually be insufficient. Instead, detailed and logical reasoning is required.