Verity Long-Droppert, Barrister at Albert Wolff Chambers, provides a case note on the East Metropolitan Health Service v Ellis  WASCA 147, which concerned factual causation, inferences, and ‘appropriate case’ causation. She will be delving further into the implications of this case, amongst other key cases at the upcoming Personal Injury WA: Quarterly Update – October on Wednesday 21 October 2020.
Western Australia’s judicial officers put their time to good use during the enforced COVID-related break from trials in the second quarter of 2020 – with several interesting decisions in the area of personal injuries being handed down in the July-September 2020 quarter. East Metropolitan Health Service v Ellis  WASCA 147 was a highlight and is worth reading in full if you have the time.
At trial, this case concerned the negligence of the appellant during the prolonged and difficult birth of the respondent. During the respondent’s birth, Dr Amira (an employee of the appellant) made a number of unsuccessful attempts to deliver the respondent by a Kiwi Cup vacuum extraction. On appeal, the following was not in dispute:
- the learned trial judge’s findings of negligence;
- that the respondent suffered periods of perinatal asphyxia meaning that around the time of his birth, he suffered from a lack of oxygen or a lack of blood supply;
- that the respondent suffered injury to his brain, or indeed that he had suffered hypoxic ischaemic encephalopathy (HIE) as a consequence of the birth process (indeed this was not in dispute at trial, it was the degree or stage of HIE that was in dispute).
There were, however, no fewer than 22 appeal grounds advanced in this appeal. On that point, the Court of Appeal had this to say:
“It is, recalling McHugh J’s observation in Tame v New South Wales, inherently unlikely that a question of causation such as this would give rise to 22 issues, or that a judge of the District Court would make so many errors. There is, in this regard, a considerable degree of overlap between the various grounds of appeal. In that context, it is worthwhile identifying a number of broad themes that emerge from the grounds and the appellant’s submissions.”
In essence, in issue in the appeal were what the learned trial judge described as the respondent’s Developmental and Cognitive impairments – at trial the respondent contended that those impairments were caused by injuries to his brain suffered in or as a consequence of the birth process. The appellant contended they were not.
Broadly speaking, the structure of the primary reasons was as follows:
The learned trial judge:
- Made findings in relation to the respondent’s injuries at the time of his birth, including the significance of the diagnosis of hypoxic ischaemic encephalopathy;
- Made findings in relation to the respondent’s developmental issues;
- Dealt with other potential causes of the respondent’s Developmental and Cognitive Impairment;
- Made a determination as to factual causation; and
- Made a determination as to the appellant’s scope of liability.
The Court of Appeal stated that based on, and drawing together all of the matters referred to above, the learned trial judge found that the respondent’s Developmental and Cognitive Impairments are more likely than not to be sequelae of his Birth Injuries, which were caused by the defendant’s fault. That was the critical finding of causation challenged in the appeal.
Court of Appeal’s Reasons
The Court of Appeal framed its reasons from the outset by reference to the principle that whether the respondent’s Developmental and Cognitive Impairments were caused by injuries to his brain resulting from the appellant’s negligence was a question of fact to be established, on the balance of probabilities. In the context of the Civil Liability Act, that factual question arises in s5C(1)(a) (i.e. factual causation): Strong v Woolworths Ltd  HCA 5.
In an attempt to distil the appeal grounds to a more manageable size (before addressing them one-by-one), WASCA identified the following themes in the appeal grounds and appellant’s submissions:
- The appellant challenged a number of primary facts found by the learned trial judge and His Honour’s preference for the opinions of some witnesses over others (in particular, the expert opinion on the significance of the results of three different MRI scans of the respondent’s brain); and
- The appellant placed much emphasis on the fact that the learned trial judge, particularly when addressing a number of the primary facts in isolation, made findings expressed in terms of what was ‘possible’. Many of the grounds of appeal relied upon passages of the primary reasons that refer to certain ‘possibilities’.
While there are many important and interesting parts to this judgment, this analysis will focus on the second theme identified by the Court of Appeal – the issue of findings expressed as “possibilities”.
Findings expressed as “possibilities”
The respondent’s case on causation required the use of inferential reasoning. The primary reasons made some findings expressed in terms of what was ‘possible’. For example, in relation to the significance of the results of the MRIs of the respondent’s brain:
“it is quite possible that the area of injury extended beyond the right cerebellar tonsil to the adjacent structures of the cerebellum, in particular the vermis, left cerebellar tonsil, flocculus and right foramen of Luschka.”
The appellant was critical of this pathway of reasoning. It argued that the possibility of something occurring was insufficient to establish the requisite causal link between breach and the plaintiff’s Developmental and Cognitive Impairments.
In addressing this theme, the Court of Appeal spent time unpacking the difference between causation in medicine and causation as a legal principle. Forgive me from quoting extensively from the judgment here, but I am afraid I would not be able to do it justice by paraphrasing:
 …the law’s concern, in relation to causation is with the attribution, in a particular case, of a causal connection between an identified negligent act or omission (or other wrong) and a given occurrence. In the context of the present case, for example, the question was whether, on the balance of probabilities, the identified negligence (for which the appellant was responsible) was the cause of the respondent’s given (or known) Developmental and Cognitive Impairments.
 To be clear: the question in the present case was not whether, in general, negligence of the kind that occurred in the present case is more or less likely to give rise to the kind of Developmental and Cognitive Impairments suffered by the respondent. No doubt that general question – the answer to which will be given by medical science – may be of importance (and may indeed by decisive) in a given case. But it would be a mistake, and potentially misleading, to confuse that scientific question with the legal one.
 As French CJ explained in Amaca v Booth, an after-the-event inference of causal connection may be breached on the balance of probabilities notwithstanding that the statistical correlation between the first event and the second event indicated, prospectively, no more than a ‘mere possibility’ that the second event would occur given the first.
 It is in this context (namely, the determination of factual causation) that the relevance of ‘possibilities’ revealed by the evidence arises for consideration.
 …it is clear, and there can be no doubt, that mere proof by a plaintiff of the possibility that a defendant’s breach caused the plaintiff to suffer harm is insufficient. The court must be satisfied that it is more probable than not that the defendant’s breach caused the relevant ham, it is not sufficient to conclude that the breach may have been a cause of the harm.
 At the same time, it is also well established that causation may be proved by inference. If direct proof is not available, an inference of causation may be drawn if the circumstantial evidence is sufficiently strong and coherent to support a definite inference to that effect. Before such an inference can be drawn, there must be more than two conflicting inferences of equal probability.
 The drawing of an inference has been described as “an exercise of the ordinary powers of human reason in the light of human experience. A court must, of course, avoid conjecture, but the distinction between permissible inference and conjecture occurs on a continuum in which there is no bright line division.
 Accordingly, even if other disciplines may not be able to give a conclusive answer, questions of causation, as a step in the determination of liability in negligence, call for ‘sufficient reduction to certainty to satisfy the relevant burden of proof for the attribution of liability.
The Court of Appeal acknowledged that there will be cases where expert evidence of a scientific or medical nature (where it is accepted) will preclude a finding of causation. For example, as Dixon J said in Adelaide Stevedoring Co Ltd v Forst in a paragraph cited with approval by the plurality in Amaca v Booth:
Upon 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.
During the appeal, the appellant submitted that this passage was authority for the proposition that the plaintiff is required to prove by expert evidence the mechanism by which a breach or its immediate consequence, caused the damage claimed by the plaintiff, at least if there is expert evidence suggesting a lack of association. The appellant submitted that, applied to this case, this requirement meant that the respondent was obliged to prove, and the learned trial judge was obliged to find, (i) an identified injury to a particular part of the brain and (ii) a scientific explanation as to how injury to that part of the brain results in cognitive or other mental deficits.
The Court of Appeal rejected that submission at  and did not accept that this requirement exists. Instead, in the Court of Appeal’s view, this passage emphasizes the restrictions upon a court’s power to hold that a plaintiff has not discharged the burden of proof. Only in circumstances where an inference of causation as unjustified as a probable inference or as an accepted hypothesis is a court positively precluded from dismissing that inference by reason of the expert evidence.
Importantly, according to this decision, nothing in the observations in Amaca v Booth requires a plaintiff to prove, or a trial judge to find, by reference to expert evidence, the specific mechanism by which one event caused another event.
The Court of Appeal then went on to address what a trial judge is able to do during the process of making a finding of inferential causation. A court may, inter alia:
- Draw an inference of causation notwithstanding that expert witnesses do not express an opinion that the damage was caused by the relevant breach;
- Draw an inference of causation without medical evidence to support it, or when the expert evidence does not rise above the opinion that a causal connection is possible if, but only if, the materials as a whole justify an inference of causation;
- Have regard to the sequence of events and call it in aid of drawing an inference which, on the medical evidence, is open;
- Make a finding of causation that is established by a process that combines primary facts like strands in a cable rather than links in a chain.
In cases where the evidence does consist of strands in a cable, rather than essential links in a chain, as long as the ultimate inference is reached to the required standard, it is not necessary for an intermediate fact to be established to the legal standard. The Court of Appeal found that in this case, causation was proved by the “strands in the cable” process.
In the end, the Court of Appeal dismissed the grounds of appeal that related to criticisms of the learned trial judge’s path of reasoning, and found that the Primary Reasons, as a whole, revealed an available and permissible path of reasoning, and adequately discharged his Honour’s obligation to disclose the intellectual process that led to his conclusion on causation.
For that (and other) reasons, despite the Court of Appeal finding that the learned trial judge erred in respect of one ground of appeal, the appeal was dismissed.
Verity Long-Droppert joined Albert Wolff Chambers in February 2018. Prior to that she worked in the Commercial Litigation team at Jackson McDonald during which time she worked on complex commercial litigation and insolvency matters. Verity accepts briefs in the areas of Personal Injuries, Insurance (Total and Permanent Disablement and Income Protection), Medical Negligence, Institutional Child Sex Abuse and National Redress Scheme, Motor Vehicle Accidents, Public Liability, Commercial Litigation and Insolvency.
Verity has appeared in the Supreme Court of Western Australia (Court of Appeal), the Federal Court of Australia, the District Court of Western Australia and the Magistrates Court. She has appeared in mediations in the Supreme Court of WA and in arbitrations and mediations at WorkCover.