In Amaca Pty Limited v Ellis State of South Australia v Ellis Millennium Inorganic Chemicals Ltd v Ellis  HCA 5 the High Court confirmed that plaintiffs still bear the onus of proving causation.
- The High Court has confirmed that a plaintiff can still succeed even if there is no direct conclusive scientific or medical evidence to establish causation.
- However, the High Court has also confirmed that it will only make inferences from other indirect evidence (such as epidemiological studies) if those studies relate to the particular facts at trial.
- Defendants can rely on this authority to place the onus on a plaintiff to establish that the studies relied on are relevant to the facts in issue. Further, the onus is on the plaintiff to establish that the studies relied on point to the conclusions which are being urged on the Court.
- The case is good news for defendants. It confirms that plaintiffs still bear the onus of proving causation and that courts will not make inferences of causation that are not supported by the evidence.
The late Mr Cotton developed lung cancer. Mr Cotton had smoked an average of 15 to 20 cigarettes a day for at least 26 years before he was diagnosed with lung cancer. He had also been exposed to asbestos dust and fibres between 1975 and 1978 during the course of his employment with the Engineering and Water Supply Department of the State of South Australia (EWSD) and between 1990 and 2002 during the course of his employment with Millennium Inorganic Chemicals Ltd (Millennium).
Mr Cotton commenced proceedings in the Supreme Court of Western Australia against EWSD, Millennium and Amaca Pty Ltd (formerly James Hardie & Co Pty Limited), the latter being the manufacturer of the asbestos cement pipes which Mr Cotton had handled during his employment with EWSD.
The medical and scientific evidence obtained could not establish the cause of Mr Cotton's cancer. Further, this evidence could not establish whether exposure to respirable asbestos fibres was a cause of Mr Cotton's cancer.
In the absence of this direct evidence, the plaintiff (who following Mr Cotton's death was the executor of his estate) was left with no alternative but to ask the Court to draw an inference of causation (between asbestos and the cancer) from the epidemiological evidence. The central question was whether it could be shown that it was more probable than not that exposure to asbestos was a cause of Mr Cotton's death.
Trial and Appeal
The plaintiff succeeded at trial and was awarded damages in excess of $1.5 million against the three defendants. The defendants' appeal to the Court of Appeal was dismissed.
In the High Court in a joint judgment, the Full Bench unanimously allowed the appeals of the three defendants, finding that causation was not established by the plaintiff against any defendant.
This is an important judgment on the issues of causation, the assessment of risk and how epidemiological evidence is to be applied.
The High Court accepted that the absence of conclusive medical or scientific evidence did not prohibit a court from reaching a particular legal conclusion as to causation. The Court accepted that conclusions could be drawn from inferences regarding the evidence and causation. The Court also accepted the epidemiological studies (studies of large groups or populations) could be relied on to draw certain legal conclusions.
However, in this case, the High Court concluded the epidemiological studies relied on by the plaintiff did not allow the Court to conclude that it was more probable than not that Mr Cotton's lung cancer had been caused by the inhalation of asbestos dust.
Indeed, the epidemiological studies relied on at the trial showed that many sufferers of lung cancer had smoked tobacco, a few had been exposed to asbestos, and some who had been exposed to asbestos had also smoked. All experts had agreed that the risk due to smoking was much greater than the risk due to exposure to asbestos dust.
The plaintiff had specifically relied on the evidence of one expert who had in part stated where there had been both asbestos inhalation and tobacco smoking it was not possible to separate their effects, and therefore it was more probable than not that the lung cancer was the singular result of the two factors acting together.
The High Court found that this statement did not mean that if a smoker had been exposed to asbestos and develops lung cancer, the asbestos exposure is, or is probably, a cause of that cancer. This was because the expert had acknowledged the precise mechanism of interaction between asbestos and tobacco smoke was not known, and the probability of causal connection could be divided between the two carcinogens (when again the asbestos inhalation had a low probability compared to the tobacco smoking).
The High Court rejected the trial judge's test of whether the aggregate exposure to asbestos was a cause of Mr Cotton's death. The High Court stated the appropriate question was whether the negligence of each particular defendant was a cause of Mr Cotton's death.
In deciding that the epidemiological evidence did not assist the plaintiff, the High Court noted that to draw an inference from what had been established in the epidemiological studies, it would be necessary to decide whether the particular case under consideration should be treated as conforming to the pattern described by the epidemiological studies. In other words, a plaintiff must establish the results of studies of populations relating to the particular case at hand.
In this case, the studies relied on by the plaintiff pointed away from the conclusion argued by the plaintiff. The studies did not show that asbestos was a cause of (a necessary condition for) Mr Cotton's cancer and did not show that exposure to asbestos made a material contribution to Mr Cotton's cancer. Material contribution could not be shown because the evidence did not establish a connection between Mr Cotton's inhaling asbestos and his developing cancer.
The High Court effectively endorsed the findings of the New South Wales Dust Diseases Tribunal in David Clarence Judd v Amaca Pty Limited  NSWDDT 12.
© DLA Phillips Fox
DLA Phillips Fox is one of the largest legal firms in Australasia and a member of DLA Piper Group, an alliance of independent legal practices. It is a separate and distinct legal entity. For more information visit www.dlaphillipsfox.com