Pre-existing medical conditions, aggravation and the burden of proof February 18, 2018
- TORTS – negligence – apportionment of responsibility and damages – medical negligence – whether pre-existing condition was progressively deteriorating – whether causation was established – whether assessment of damages could be challenged – challenges to findings of fact and damages dismissed
- Macfarlan JA at ;
Payne JA at ;
White JA at 
- The primary judge accepted that the Hospital’s negligence materially contributed to an increased burden of Ms Pierce’s epilepsy. Ms Pierce submitted that accordingly the Hospital had the onus of adducing evidence that the worsened burden of her incapacity was partly the result of her pre-existing condition. In Purkess v Crittenden Barwick CJ, Kitto and Taylor JJ said (at 168):
“… where a plaintiff has, by direct or circumstantial evidence, made out a prima facie case that incapacity has resulted from the defendant’s negligence, the onus of adducing evidence that his incapacity is wholly or partly the result of some pre-existing condition or that incapacity, either total or partial, would, in any event, have resulted from a pre-existing condition, rests upon the defendant. In other words, in the absence of such evidence the plaintiff, if his evidence be accepted, will be entitled to succeed on the issue of damages and no issue will arise as to the existence of any pre-existing abnormality or its prospective results, or as to the relationship of any such abnormality to the disabilities of which he complains at the trial. It was, we think, with the character and quality of the evidence required to displace a plaintiff’s prima facie case that Watts v. Rake  HCA 58; (1960) 108 CLR 158 was essentially concerned. It was, in effect, pointed out that it is not enough for the defendant merely to suggest the existence of a progressive pre-existing condition in the plaintiff or a relationship between any such condition and the plaintiff’s present incapacity. On the contrary it was stressed that both the pre-existing condition and its future probable effects or its actual relationship to that incapacity must be the subject of evidence (i.e. either substantive evidence in the defendant’s case or evidence extracted by cross-examination in the plaintiff’s case) which, if accepted, would establish with some reasonable measure of precision, what the pre-existing condition was and what its future effects, both as to their nature and their future development and progress, were likely to be. That being done, it is for the plaintiff upon the whole of the evidence to satisfy the tribunal of fact of the extent of the injury caused by the defendant’s negligence.” (emphasis added)
- This was said in the context of a personal injury case arising from a motor vehicle accident. The plaintiff experienced severe and disabling pain in her cervical region. There was evidence that before the accident she suffered from degenerative changes in the spine which were most marked in the cervical region. It was asserted for the defendant that it was probable that at some unspecified time she would have become similarly disabled even if she had not been injured in the motor vehicle accident. The High Court held that the medical evidence upon which the defendant relied, that was accepted by the trial judge, did not establish with any reasonable degree of precision the extent of the plaintiff’s pre-existing condition or its likely future effects (at 169).
- In the present case the Hospital discharged its evidentiary onus of establishing that Ms Pierce’s pre-existing condition was one of likely progressive deterioration. She had the legal burden of establishing the extent to which the Hospital’s negligence damaged her. No reasonable precision was possible either of the likely progression of her epilepsy in the absence of the telemetry event, nor of the extent to which the defendant’s negligence worsened her existing condition. The defendant’s negligence in the present case was in the treatment of an existing condition that is factually remote from the circumstances in Watts v Rake and Purkess v Crittenden.
- In Seltsam Pty Ltd v Ghaleb  NSWCA 208; (2005) 3 DDCR 1, Ipp JA, with whom Mason P agreed, said in relation to Malec v J C Hutton Pty Ltd:
“103 Therefore, according to Malec:
(a) In the assessment of damages, the law takes account of hypothetical situations of the past, future effects of physical injury or degeneration, and the chance of future or hypothetical events occurring.
(b) The court must form an estimate of the likelihood that the alleged hypothetical past situation would have occurred.
(c) The court must form an estimate of the likelihood of the possibility of alleged future events occurring.
(d) These matters require an evaluation of possibilities and are to be distinguished from events that are alleged to have actually occurred in the past, which must be proved on a balance of probabilities.
104 What was said in Watts v Rake and Purkess v Crittenden now has to be qualified by these principles (cf Commonwealth of Australia v Elliott  NSWCA 360 at ). Malec has an important bearing, for example, on the way in which a court must determine whether a defendant has discharged the ‘disentangling’ evidentiary burden on it of showing that part of the plaintiff’s condition was traceable to causes other than the accident and that, had there been no accident, the plaintiff would have suffered disability from his pre-existing condition.”
- The fact that Ms Pierce suffered epilepsy that was likely to deteriorate progressively was to be determined on the probabilities. The likely extent of the progression of her condition was an issue to which the principles in Malec v J C Hutton Pty Ltd applied. The fact that Ms Pierce’s epilepsy was a progressively deteriorating condition was established on the balance of probabilities.
- Whether the Hospital’s negligence in not responding to the induced seizures in a timely manner materially contributed to Ms Pierce’s worsened condition is not to be determined on the basis of scientific certainty, but on the balance of probabilities. As Spigelman CJ said in Seltsam Pty Ltd v McGuiness(2000) 49 NSWLR 262;  NSWCA 29 at :
“An inference of causation for purposes of the tort of negligence may well be drawn when a scientist, including an epidemiologist, would not draw such an inference.”
- The primary judge applied the principles stated by Herron CJ, with whom Asprey and Holmes JJA agreed (at 245), in EMI (Australia) Ltd v Bes  2 NSWR 238 at 242 that:
“… it is not incumbent upon the applicant, upon whom the onus rests, to produce evidence from medical witnesses which proves to demonstration that the applicant’s contention is correct. Medical science may say in individual cases that there is no possible connexion between the events and the death, in which case, of course, if the facts stand outside an area in which common experience can be the touchstone, then the judge cannot act as if there were a connexion. But if medical science is prepared to say that it is a possible view, then, in my opinion, the judge after examining the lay evidence may decide that it is probable. It is only when medical science denies that there is any such connexion that the judge is not entitled in such a case to act on his own intuitive reasoning. It may be, and probably is, the case that medical science will find a possibility not good enough on which to base a scientific deduction, but courts are always concerned to reach a decision on probability and it is no answer, it seems to me that no medical witness states with certainty the very issue which the judge himself has to try.
- In Fernandez v Tubemakers of Australia Ltd  2 NSWLR 190 Glass JA said (at 197) that a finding of causal connection may be open without any medical evidence at all to support it, or when the expert evidence does not rise above the opinion that a causal connection is possible.
- In Adelaide Stevedoring Co Ltd v Forst (1940) 64 CLR 538 the High Court, by majority, upheld the conclusion of the Supreme Court of South Australia that a worker’s death from coronary thrombosis was contributed to by muscular exertion in the course of his employment and thus was a result of an injury by accident arising out of and in the course of his employment that was compensable under the Workmen’s Compensation Act 1932–1935 (SA). Rich ACJ, Starke and McTiernan JJ each considered that the close proximity to the worker’s engaging upon the heavy work and his death, coupled with medical evidence that did not exclude, although on one view it did not support, a connection between exertion and coronary thrombosis, justified the finding that on the balance of probabilities the heavy work materially contributed to the coronary thrombosis and death (per Rich ACJ at 563-4, per Starke J at 566-7; and per McTiernan J at 574).
- Dixon J, in dissent, said (at 569):
“First, I think that upon a question of fact of a medical or scientific description, a court can only say that the burden of proof has not been discharged where, upon the evidence, it appears that the present state of knowledge does not admit of an affirmative answer, and that competent and trustworthy expert opinion regards an affirmative answer as lacking justification, either as a probable inference or as an accepted hypothesis.”
- This passage was referred to with apparent approval by Mason J (with whom Barwick CJ and Gibbs J agreed) in Tubemakers of Australia Ltd v Fernandez (1976) 10 ALR 303 at 311. In the present case Professor Dunne regarded it as an accepted hypothesis that the telemetry event of 5 January 2010 materially contributed to the increased frequency of seizures suffered by Ms Pierce after that event. Dr Fong regarded that as a probable inference, as did the primary judge.