In Evans v Queanbeyan City Council  NSWCA 230, the Court of Appeal held that the law of negligence requires that a plaintiff prove, on the balance of probabilities, that the defendant's wrong caused or materially contributed to his or her loss; it is not sufficient for the plaintiff to show that the wrong materially increased the risk of harm, where medical science does not permit any further proof.
Mr Evans was employed by the first respondent (Queanbeyan City Council) from 1975 to 1990. In the course of this employment Mr Evans was exposed to asbestos. The second respondent (Amaca Pty Ltd, formerly James Hardie & Coy Pty Ltd) manufactured asbestos building products used by Mr Evans through much of his working life. For approximately 40 years of his life up until 1991, Mr Evans was a heavy smoker. In 2006, he was diagnosed with lung cancer. The applicant (Mr Evans' widow) brought a claim before the Dust Diseases Tribunal (DDT) claiming that Mr Evans' lung cancer had resulted from exposure to asbestos dust in circumstances imposing liability on the respondents. Whilst the DDT did find that Mr Evans had experienced significant exposure to asbestos, the DDT was not satisfied on the balance of probabilities that Mr Evans' lung cancer was caused by his exposure to asbestos. Mr Evans' widow appealed against that decision to the Supreme Court of NSW under s32(1) of the Dust Diseases Tribunal Act 1989 (NSW).
The Court of Appeal unanimously dismissed the appeal.
The most important aspect of the judgment was in relation to the appellant's submission that the DDT had fallen into legal error by failing to apply what should be taken to be the law of causation in negligence claims.
The appellant submitted that it was sufficient to attribute causal responsibility to a defendant in circumstances where that defendant materially increased the risk to that plaintiff of suffering an injury and that injury occurred, where medical science was unable to provide a conclusion for causation to be made on the balance of probabilities. This argument was rejected on the basis that it was inconsistent with Australian case law notwithstanding that the appellant had failed to identify any Australian authority for the proposition that tortiously increasing the risk of harm suffices for causation of harm. In the leading judgment, Allsop P concluded that:
The appellant contended that the primary judge had used evidence for a different purpose to that with which it was led and that this approach was incorrect. The appellant had led both evidence of a biological synergistic effect of asbestos dust and tobacco smoke in causing lung cancer, as well as separate epidemiological evidence. The primary judge rejected the synergistic evidence on the basis that it was inconsistent with the epidemiological evidence presented. The Court of Appeal held that the DDT had been entitled to reject the hypothesis that asbestos and smoking have a synergistic biological effect; this was a purely factual exercise and although the judge had been satisfied that there might well be a synergistic effect in cases of asbestos and smoking, he was not satisfied that this effect must occur in the majority of cases, especially that of Mr Evans. According to Hodgson JA, there was no inconsistency in the primary judge's findings that exposure to asbestos had been significant, yet on the balance of probabilities that its contribution to the causation of cancer in a heavy smoker was not significant.
In addition, the appellant contended that the primary judge had gone beyond his position as an expert tribunal by going outside the evidence to calculate fibre load. This was rejected on the basis that there was no error in law and that the primary judge was entitled to make his own calculations about the level of exposure to asbestos dust and the resultant risks involved.
Finally, the appellant submitted that the primary judge had not adopted a "but for" test of causation; his Honour had not properly considered material causation in circumstances where the asbestos dust and smoking had operated causally. This argument was rejected by the Court of Appeal.
In his judgment, Allsop P noted that in the current case the primary judge had concluded that the contribution of asbestos to Mr Evan's lung cancer was not material, and therefore he did not reach the threshold for considering the appropriate test to be used for causation where there is a material risk. Further, in his discussion of "material risk" his Honour considered the UK cases of Fairchild v Glenhaven Funeral Services Ltd  UKHL 22, Barker v Corus UK Ltd  UKHL 20 and Sienkiewicz (Administratrix of the Estate of Enid Costello Deceased) v Grief (UK) Ltd  UKSC 10 where there is an accepted special rule in the UK common law for mesothelioma cases. His Honour acknowledged that the statement of principles outlined in Sienkiewicz is not necessarily limited to cases of mesothelioma. When reconciling these cases with the Australian position, his Honour was able to identify policy questions in Fairchild and Barker that were fundamental to allowing a causal connection to be made on the basis of increased risk in those cases. His Honour went on to conclude that for Australia to adopt this position, the High Court would have to resolve these policy questions.
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