Judgment date: 3 March 2010, Amaca Pty Ltd v Ellis; the State of South Australia v Ellis; Millennium Inorganic Chemicals Ltd v Ellis  HCA 5, High Court of Australia1.
- The High Court was asked to determine whether it was more probable than not that exposure to respirable asbestos fibres was a cause of the deceased's lung cancer.
- The High Court overturned the decision of the Western Australian Court of Appeal and found that it was not demonstrated that the deceased's exposure to asbestos made a material contribution to his lung cancer.
- Scientific evidence which establishes that exposure to asbestos may have been a cause for the development of lung cancer is not a sufficient basis for attributing legal responsibility.
Mr Cotton (the deceased) had smoked on average somewhere between 15 and 20 cigarettes per day for in excess of 26 years prior to being diagnosed as suffering from lung cancer in May 2000. The deceased was subjected to occupational exposure to asbestos whilst employed by the Engineering and Water Supply Department of South Australia and by Millennium Inorganic Chemicals Limited.
The deceased's Estate pursued a claim for damages, interest and costs as compensation for the deceased's lung cancer and ultimate death arising out of his exposure to materials containing asbestos dust and fibre.
Supreme Court Decision
The trial judge (Heenan J) found that each of the defendants had been negligent in causing the deceased to be exposed to materials containing asbestos amounting to a breach of the duty of care owed to the deceased and his dependants.
Judgment was entered in favour of both the Estate claim and the dependants' claim for the total sum of $1,526,663.30 plus costs.
Court of Appeal Decision
The majority of the Court of Appeal (Steytler P and McLure JA, Martin CJ dissenting) dismissed each of the appeals pursued by the defendants.
The defendants argued that the trial judge made factual and legal errors in his assessment of the question of whether the defendants' breaches of duty had caused or materially contributed to the causation of Mr Cotton's lung cancer.
It was also argued that the trial judge erred (in fact) in the findings which he made with respect to the synergistic interaction of the carcinogens found in tobacco smoke and asbestos fibre, and that he erred (in law) in the approach which he took to the assessment of a contribution which was 'material'.
The majority of the Court of Appeal accepted "medical evidence, reflected in the acknowledged synergistic effect of tobacco smoke and asbestos, that tobacco smoke and asbestos fibres operated inter-dependently and thus cumulatively to cause Mr Cotton's lung cancer."
High Court Decision
The court comprised French, CJ, Gummow, Hayne, Heydon, Crennan, Kiefel and Bell, JJ and they delivered a unanimous judgment.
The fundamental question which the High Court was required to determine was whether it had been established to be more probable than not that exposure to asbestos was a cause of the deceased's lung cancer and ultimate death. The High Court was not required to consider whether a duty of care existed or whether there had been a breach of any such duty owed.
The High Court considered the wealth of medical and scientific evidence adduced in the primary action and subsequent appeal.
The epidemiological evidence demonstrated that many sufferers of lung cancer had smoked tobacco, a few had been exposed to asbestos; some of those who had been exposed to asbestos had also smoked; some had been neither smokers nor exposed to asbestos. The data obtained from the studies was used to provide measures of "relative risk" being the ratio of the risk of disease or death among the exposed to the risk among the unexposed.
The lowest assessment provided as to the probability of the deceased's lung cancer being caused by his smoking history only, was 67%. A probability that the deceased's lung cancer was caused by his exposure to asbestos only, was assessed at 3% and the probability that the combined effect of the deceased's smoking history and exposure to asbestos caused his lung cancer was 20%.
Whilst there was some variance in the opinions provided by the various experts, all agreed that there was a significantly greater relative risk of contracting lung cancer from tobacco smoke compared to the relative risk created by exposure to asbestos.
The High Court observed that whilst exposure to asbestos may have been a cause of the deceased's lung cancer, it was not demonstrated that the deceased's cancer and ultimate death was brought about by the negligent acts or omissions of the defendants.
Before the High Court, the plaintiff submitted that in determining whether or not the deceased's exposure to asbestos had made a material contribution to the development of the deceased's lung cancer, consideration should be given to the decision of the House of Lords in Bonnington Castings Ltd v Wardlaw2 and, in particular, the statement of Lord Reid3 that:
"What is a material contribution must be a question of degree. A contribution which comes within the exception de minimis non curat lex is not material, but I think that any contribution which does not fall within that exception must be material."
The High Court observed that Bonnington Castings4 did not address the question as to what was the probable source of the pursuer's disease, the question was whether one source of an injurious substance contributed to a gradual accumulation of dust that resulted in disease. That question is distinguishable from the question which the High Court was required to consider in these proceedings, that was whether one substance that can cause injury did cause injury.
The High Court found that it was not established that the deceased's exposure to asbestos had made a material contribution to the development of his lung cancer. In addressing the medical and scientific evidence, the High Court stated that it must "reduce to legal certainty [a question] to which no other conclusive answer can be given5 and that the courts do that by asking whether it is more probable than not that X was a cause of Y. Saying only that exposure to asbestos may have been a cause of Mr Cotton's cancer is not a sufficient basis for attributing legal responsibility"6
The High Court allowed the appeals from all three defendants.
Because of the way in which the plaintiff's case was presented it was not necessary for the court to consider the United Kingdom approach to causation in the cases of McGhee v National Coal Board7, Fairchild v Glenhaven Funeral Services Limited8 and Barker v Corus UK Limited9.
The Australian approach to causation remains valid. It is not sufficient to demonstrate that the defendant's conduct for example by exposing the plaintiff to a "dangerous" substance increased the risk of the plaintiff contracting a disease. The plaintiff still has to prove that exposure to the dangerous substance caused or materially contributed to the plaintiff's condition.
The decision also indicates the importance of taking care with epidemiological evidence. If an inference is to be drawn from epidemiological studies it must relate the results of the studies of the populations to the particular case at hand.
The maxim adopted in some courts that "all exposure [to asbestos] is causative" when dealing with the question of causation in malignant claims, may no longer be supported in cases where there may be alternative potential causes of a claimant's injury.
1. French CJ, Gummow, Hayne, Heydon, Crennan, Kiefel and Bell JJ
2.  UKHL 1
3. 1956] UKHL 1
4.  UKHL 1
5. Bank of NSW v The Commonwealth  HCA 7
6. at 70
7.  UKHL 7
8.  UKHL 22
9.  UKHL 20
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