HCA – medical negligence claims & lost chance of a better outcome

Tabet v Gett [2010] HCA 12 (21 April 2010)

Whilst all their Honours dismissed the appeal, the decision was not unanimous (as is becoming the norm) however, with the exception of Gummow ACJ, the balance agreed with Kiefel J.

The issue to be determined was whether a claim in negligence having failed in breach of duty, can succeed in the alternative as a ‘lost chance of a better outcome’ of a treatment, or in this case an earlier CT scan. The claim was based in negligence and not alternatively in contract.

The trial judge assessed the lost chance at 40%, resulting in overall 25% damage. One appeal to the NSW Court of Appeal this was reduced to 15%. The trial judge’s assessment was not based on expert evidence.

The facts as summarised were:


The significant events which followed, and the course of the 36-day trial before Studdert J[1], were described as follows by the Court of Appeal (Allsop P, Beazley and Basten JJA)[2]:

“On 14 January 1991, after suffering a seizure, and after a CT scan and EEG were performed [the appellant] was diagnosed as suffering from a brain tumour. She received treatment, including an operation to remove the tumour. She suffered irreversible brain damage, partly as a result of events on 14 January 1991, partly from the tumour (which had been growing for over 2 years), and partly from the operative procedure and other treatment (not said to be in any way negligently performed).
The [appellant] brought proceedings against the [respondent] in negligence. The central allegation was that the CT scan that was undertaken on 14 January should have been performed earlier, either on 11 or 13 January, and that if it had, she would have had a better medical outcome. The plaintiff also brought proceedings against Dr Mansour, who had treated her in an earlier admission to hospital on 29-31 December 1990. The trial judge held that Dr Mansour was not negligent in his treatment of the [appellant] and there is no appeal from that decision.
The trial judge held, however, that the [respondent] was negligent in failing to order a CT scan on 13 January 1991. His Honour found no earlier negligent act or omission, thereby concluding that the [respondent] acted reasonably in making his provisional diagnosis on 11 January that the [appellant] was suffering from chickenpox or varicella meningitis or encephalitis.”

Their Honours distinguished claims based in contract and commercial comparisons of lost chance of opportunity, noting contract is founded on ‘breach’ whereas negligence requires ‘damage’ as an element.

Some significant detail was allocated to considering overseas jurisdictions. It seems the crucial difference which emerged was the varying degrees of proof and the standard required. Ultimately, Keifel J determined the matter on the standard of proof having not been met:


The common law requires proof, by the person seeking compensation, that the negligent act or omission caused the loss or injury constituting the damage. All that is necessary is that, according to the course of common experience, the more probable inference appearing from the evidence is that a defendant’s negligence caused the injury or harm. “More probable” means no more than that, upon a balance of probabilities, such an inference might reasonably be considered to have some greater degree of likelihood; it does not require certainty[97].


The “but for” test is regarded as having an important role in the resolution of the issue of causation, although more as a negative criterion than as a comprehensive test[98]. The resolution of the question of causation has been said[99] to involve the common sense idea of one matter being the cause of another. But it is also necessary to understand the purpose for making an inquiry about causation[100] and that may require value judgments and policy choices[101].


Once causation is proved to the general standard, the common law treats what is shown to have occurred as certain[102]. The purpose of proof at law, unlike science or philosophy, is to apportion legal responsibility[103]. That requires the courts, by a judgment, to “reduce to legal certainty questions to which no other conclusive answer can be given.”[104] The result of this approach is that when loss or damage is proved to have been caused by a defendant’s act or omission, a plaintiff recovers the entire loss (the “all or nothing” rule).


Resort to the language of “chance” cannot displace the analysis necessary for the determination of the issue of causation of damage. Properly analysed, what is involved in the chance referred to in this case is the possibility, to put it at its highest, that no brain damage would occur or that it would not be so severe. They are the “better medical outcomes” involved in the chance. Expressing what is said to be the loss or damage as a “chance” of a better outcome recognises that what is involved are mere possibilities and that the general standard of proof cannot be met. Thus the appellant could only succeed if the standard of proof is lower than the law presently requires.


Gregg v Scott confirmed for the United Kingdom that the general standard of proof should be maintained with respect to claims for damages for medical negligence. Lord Nicholls was the only member of the House of Lords to consider that the law should not require proof on the balance of probabilities and should recognise a person’s prospects of recovery as real[161]. The Supreme Court of Canada in Laferrière v Lawson confirmed that if a case did not meet the test of causation applying the general standard of proof, then recovery should be denied[162].


The general standard of proof required by the common law and applied to causation is relatively low. It does not require certainty or precision. It requires that a judge be persuaded that something was probably a cause of the harm the plaintiff suffered. Historically the standard may have been chosen in order to minimise errors in civil jury trials[163], but it nevertheless serves also to accommodate a level of uncertainty in proof.


In countries like France evidence must approach certainty in proof of causation[164]. Gonthier J considered the different standards between the law of France and of Quebec – which, generally speaking, applies the common law standard – to be significant in relation to the approaches taken by the courts of those countries[165]. Professor Khoury considers that the strictness with which French courts approach the high standard of proof may have led them to resort to the loss of chance solution[166].


In Germany, where there is also a high standard of proof, the problem of proof in negligence cases is dealt with by a reversal of the burden of proof. This arises in cases of medical negligence[167]. Where it is proved that a doctor was grossly negligent, the doctor must prove that his or her actions were not the cause of the injury. The term “gross negligence” is not applied restrictively. An action which is contrary to generally acknowledged rules of medical treatment, such as not performing a necessary investigation, will suffice[168].


The standard of proof required by the common law already admits of some uncertainty in proof of causation. As Lord Hoffmann observed in Gregg v Scott, the wholesale adoption of possible rather than probable causation as a condition of liability is radical[169].


The common law has also shown itself to be adaptable in relation to its treatment of evidence of causation in cases where there is difficulty of proof. In Snell v Farrell[170] the Supreme Court of Canada has countenanced an approach, in medical negligence cases, where inferences might more readily be drawn adverse to a defendant, because the facts lie particularly within the defendant’s knowledge. The inference drawn by members of this Court in Adelaide Stevedoring Co Ltd v Forst is noteworthy[171]. The decisions in McGhee v National Coal Board[172] and Fairchild v Glenhaven Funeral Services Ltd[173] are perhaps more controversial. In this case, however, it is not suggested that any of these approaches are possible and it is not necessary to further consider these decisions.


When an issue is proved to the general standard the court treats the damage caused as certain, thus giving rise to the all-or-nothing rule of recovery. The rule is strongly criticised by those who favour acceptance of loss of chance as damage[174]. However, the rule reflects the certainty that the law considers to be necessary when attributing legal responsibility for harm caused. To replace it with a rule which limits damages awarded according to the degree of probability of causation has its own limitations. It would suggest, if not require, a degree of precision in the assessment of probabilities which is not part of the more liberal, common sense, approach presently undertaken. And, as Baroness Hale of Richmond observed in Gregg v Scott, proportionate recovery cuts both ways[175].


It would require strong policy considerations to alter the present requirement of proof of causation. None are evident. The argument that there should be compensation where breach of duty is proved simply denies proof of damage as necessary to an action in negligence. I am unpersuaded that denial of recovery in cases of this kind would fail to deter medical negligence or ensure that patients receive an appropriate standard of care. These matters appear to have been influential in Matsuyama v Birnbaum. However, a feature of that case was that the defendant was called as a witness and gave evidence that an effect of the particular contract between Mr Matsuyama’s medical insurer and the doctors’ practice to which the defendant belonged was that doctors had difficulty in providing patients qualifying for treatment under it with the best medical care[176].

Brisbane Barrister – David Cormack


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