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Plunkett, James --- "Causation in the High Court of Australia: A matter of common sense?" [2019] PrecedentAULA 42; (2019) 153 Precedent 10


CAUSATION IN THE HIGH COURT OF AUSTRALIA
A MATTER OF COMMON SENSE?

By Dr James Plunkett

As any good lawyer will know, in order to recover damages for negligence, a plaintiff must establish that not only did the defendant breach the duty of care that they owed to the plaintiff, but also that the breach of duty caused the damage that is the subject of the complaint. While the causal enquiry is typically a straightforward one, this is not always so; indeed, the concept of causation is a slippery one, and much ink has been spilled, by both lawyers and philosophers alike, on what causation actually means.

Insofar as the common law of Australia is concerned, most readers will likely recall from their university days that ‘questions of cause and consequence are not the same for law as for philosophy and science’,[1] and matters of causation have instead tended to be resolved as a matter of ‘common sense’. Yet, the law has evolved and more recently the common sense approach to causation has fallen out of fashion and been replaced by a statutory formulation that requires a twofold enquiry. This article explores that statutory formulation, as well as how it has been approached and applied by the High Court of Australia in a number of important decisions.

‘COMMON SENSE’ CAUSATION

Although its origins lie in much earlier times,[2] the common sense approach to causation was first approved by the High Court in Fitzgerald v Penn,[3] where it was said that causation is ‘all ultimately a matter of common sense’. Not long after that decision, the common sense approach received the endorsement of two highly influential Oxford legal academics, Hart and Honoré, in their widely cited Causation in the Law.[4] But, as most readers will know, the idea that questions of causation are ‘to be resolved by the application of common sense’ only really gained traction in Australia following the judgment of Mason CJ in March v Stramare Pty Ltd.[5] In this case, the defendant (Stramare) parked a truck in the middle of the road while they were unloading items into a shop. The plaintiff (March), who was both speeding and drunk, crashed his car into the back of the defendant’s stationary truck, and suffered physical injury as a result. While the plaintiff argued that the cause of the accident was the defendant’s parking of the truck in the middle of the road, the defendant argued that the ‘real’ cause was the plaintiff’s careless driving. The High Court ultimately found for the plaintiff, as the defendant's act in parking the truck in the middle of the road was wrong because it created a risk that a careless driver would run into the back of it, and this was the very risk that had in fact materialised.

Despite its judicial and academic support, the common sense approach to causation was not without its limitations. As noted by Gummow, Hayne and Crennan JJ in Amaca v Booth:

‘[M]any issues of causation ... lie outside the realm of common knowledge and experience. They fall to be determined by reference to expert evidence, for example, medical evidence. In such cases, the investigation of difficult and complicated facts cannot be separated from an appreciation of any special branch of knowledge which affects them.’[6]

Indeed, as those who practise in medical negligence will know, questions of causation frequently require the opinion of expert medical witnesses, rather than the application of the layperson’s common sense.

The language of ‘common sense’ also has the tendency to discourage the proper articulation of reasons why causation has or has not been established, and instead conceals them behind the vague statement that ‘it is all a matter of common sense’. As noted by Edelman J, for example, writing extra-judicially:

‘The “common sense approach” is not a meaning of causation. It invites the judge or jury to reason by reference to unstated premises and to assert as “common” a conclusion that is often highly contested.’[7]

Professor Stapleton, one of the most vocal critics of common sense causation,[8] suggests that courts should therefore reject the ‘packaging of disputes in vague causal terminology’,[9] as it tends to conceal what is in fact two discrete enquiries:[10]

1. the question of fact about whether the tortious conduct of the defendant was historically involved with the plaintiff suffering actionable damage; and

2. the normative inquiry into whether the consequence of the tort that the plaintiff is complaining about should be judged to be within the appropriate scope of liability for consequences of the tortious conduct.

Professor Stapleton’s ideas on causation have proved highly influential and, following the recommendations of the 2002 Review of the Law of Negligence: Final Report (better known as the ‘Ipp Report’), they were ultimately enshrined in statute in all Australian jurisdictions, except for the Northern Territory. In Victoria, for example, the relevant legislation reads as follows:

‘(1) A determination that negligence caused particular harm comprises the following elements—

(a) that the negligence was a necessary condition of the occurrence of the harm (factual causation); and

(b) that it is appropriate for the scope of the negligent person's liability to extend to the harm so caused (scope of liability).’[11]

Accordingly, when faced with causal problems, courts are now required to isolate the scientific ‘factual causation’ issue from the normative ‘scope of liability’ issue. It is no longer good enough to simply say that causation is (or is not) established as ‘a matter of common sense’.

FACTUAL CAUSATION AND THE BUT-FOR TEST

Factual causation is a question of fact about whether the tortious conduct of the defendant was historically involved with the plaintiff suffering actionable damage. The enquiry is normatively neutral, and will often require the use of expert evidence. In terms of the law, little needs to be said about the factual causation enquiry other than that, as the High Court has repeatedly affirmed,[12] it is to be resolved by an application of the well-known ‘but-for’ test. The position was probably best put by the majority in Wallace v Kam:

‘The determination of factual causation in accordance with [the legislation] involves nothing more or less than the application of a "but for" test of causation. That is to say, a determination ... that negligence was a necessary condition of the occurrence of harm is nothing more or less than a determination on the balance of probabilities that the harm that in fact occurred would not have occurred absent the negligence.’[13]

‘MATERIAL CONTRIBUTION’ TO HARM

So far, so good. However the but-for test is not without its own limitations, and is particularly problematic in cases where the plaintiff’s claimed damage is able to be explained by multiple sufficient causes[14] or where science is not sufficiently advanced to determine whether the claimed cause in fact played a role in bringing about the plaintiff’s damage. These problems most commonly arise in dust disease cases, and in particular cases where the plaintiff suffers from mesothelioma, a cancer that is almost exclusively caused by exposure to asbestos. Such cases give rise to difficult causal problems because mesothelioma victims tend to have been exposed to asbestos by a number of independent tortfeasors, and, due to the limits of medical science, are typically unable to prove which, if any, of those tortfeasors was a but-for cause of their disease; in other words, the defendants can all legitimately say, ‘but for my negligence the plaintiff would have probably suffered the damage anyway’.

A strict application of the but-for test would leave many mesothelioma victims without legal redress. Conscious of the potential unfairness of such a situation,[15] the Ipp legislation explicitly creates a statutory exception for such cases. In Victoria, the relevant legislation reads:

‘In determining in an appropriate case, in accordance with established principles, whether negligence that cannot be established as a necessary condition of the occurrence of harm should be taken to establish factual causation, the court is to consider (amongst other relevant things) whether or not and why responsibility for the harm should be imposed on the negligent party.’[16]

While there have so far been no cases in the High Court to test this section (or its equivalent in another jurisdiction), it is likely that the section is aimed at situations where the defendant’s negligence can only be said to have ‘materially contributed’ to the damage, which the common law already recognises as an exception to the but-for test for causation. As explained by the High Court in Booth:

‘The "but for" criterion of causation proved to be troublesome in various situations in which multiple acts or events led to the plaintiff's injury, for example, where the development of a particular medical condition was the result of multiple conjunctive causal factors. In such cases what may be unclear is the extent to which one of these conjunctive causal factors contributed to that state of affairs. These situations have been addressed by the proposition stated by Lord Watson in Wakelin v London and South Western Railway Co that it is sufficient that the plaintiff prove that the negligence of the defendant "caused or materially contributed to the injury." In that regard, reference may be made to the well-known passage in the speech of Lord Reid in Bonnington Castings Ltd v Wardlaw ...’[17]

Yet, aside from telling us that a ‘material contribution’ is distinct from, and an outright exception to, ‘but-for’ causation, the above passage tells us only what material contribution doesn’t meanit completely fails to articulate what material contribution does mean. Indeed, the only guidance to be found from the High Court on the meaning of ‘material contribution’ is the obiter comments of the majority in Amaca v Ellis,[18] ultimately to the effect that to show a ‘material contribution’ between the defendant’s negligence and the plaintiff’s damage, the plaintiff must establish a ‘connection’. Such ‘guidance,’ if indeed it can be called guidance at all, simply replaces one ambiguous concept with another, and so fails to advance our understanding of material contribution. While the pessimist might therefore take the view that the High Court is shirking in its duty to provide clear and unambiguous guidance on the law, the optimist, on the other hand, might say that the High Court is simply weary of the English experience, where judicial attempts to limit exceptions to the but-for test (for example, where the defendant’s negligence merely increased the risk that the plaintiff would suffer damage) have proved highly unsatisfactory,[19] and so, not wanting to create more problems than it solves, has therefore consciously chosen to keep Pandora’s Box firmly shut.

THE SCOPE OF LIABILITY

Not all but-for consequences of a defendant’s negligence, however, are necessarily attributed to the defendant; rather, a defendant is responsible only for those consequences of which he is deemed to be the ‘legal’ cause, or those consequences which the law deems ought to fall within the ‘scope of the defendant’s liability’ for negligence. Unlike the factual causation enquiry, the scope of liability enquiry is not a scientific enquiry, but a normative one – an ought question. In layperson’s terms, it deals with the problem of ‘Adam and Eve’ liability, and permits the law to effectively draw a line in the sand, and deem a defendant responsible for only so many of the consequences of their negligence and no more.

The most well-known limits on a defendant’s liability for carelessly caused harm are the law of remoteness – which largely limits a defendant’s liability to the consequences of their negligence that were foreseeable[20] – and the law relating to novus actus interveniens. Yet, the scope of liability stage also does not require defendants to compensate plaintiffs for the materialisation of a risk that is different to the risk that made their conduct negligent in the first place.

The leading case in this regard is Wallace v Kam. Here, the plaintiff was required to undergo spinal surgery. The surgery involved two principal risks: one minor (the risk of nerve damage to the thighs) and one major (the risk of catastrophic paralysis). The defendant negligently failed to warn the plaintiff of either risk and the plaintiff underwent the surgery. The first risk materialised. It was held at trial, however, that if the plaintiff had been warned of the risks, while he would not have accepted the second risk, he would have accepted the first risk. Factual causation was therefore established, but only in relation to the failure to warn of a risk that did not materialise. The High Court unanimously found for the defendant on the basis that the plaintiff was ‘not to be compensated for the occurrence of physical injury the risk of which he was prepared to accept’.[21]

The point is a fine one, and is perhaps better illustrated by an example given by Lord Hoffmann in the well-known House of Lords case, SAAMCO.

‘A mountaineer about to undertake a difficult climb is concerned about the fitness of his knee. He goes to a doctor who negligently makes a superficial examination and pronounces the knee fit. The climber goes on the expedition, which he would not have undertaken if the doctor had told him the true state of his knee. He suffers an injury which is an entirely foreseeable consequence of mountaineering but has nothing to do with his knee.’[22]

While Wallace v Kam occurred in a medical context, there is no reason to believe that it does not create a rule of causation of general application; that is, that the law limits a defendant’s liability to those consequences which are attributable to that which made his act wrongful.

CONCLUSION

Justice Ipp has said that the principles embodied in the abovementioned legislation are ‘in accord with the common law[23] – that is, the common sense approach to causation. To the extent that the statutory formula should not lead to different outcomes to the common sense approach, Ipp JA is surely right. However, there can be little doubt that the legislative approach requires courts to provide a much clearer articulation of the reason for those outcomes, and must go beyond merely labelling them ‘common sense,’ which is ultimately better seen as a conclusion, and not a method that provides particularly helpful guidance in reaching one.

Dr James Plunkett is a barrister at the Victorian Bar. He has previously taught law at the University of Oxford and practised at the Bar of England and Wales. EMAIL plunkett@vicbar.com.au.


[1] The National Insurance Co. of New Zealand Ltd v Espagne [1961] HCA 15; (1961) 105 CLR 569, 591 (Windeyer J).

[2] J Edelman, ‘Unnecessary causation’, Australian Law Journal, Vol. 89, 2015, 21.

[3] [1954] HCA 74; (1954) 91 CLR 268, 277 (Dixon CJ, Fullagar and Kitto JJ).

[4] HLA Hart and T Honoré, Causation in the Law, Clarendon Press, Oxford, 1959.

[5] [1991] HCA 12; (1991) 171 CLR 506, [18].

[6] [2011] HCA 53; [2011] 246 CLR 36, [67] (Booth).

[7] Edelman, above note 2, 20.

[8] See, for example, J Stapleton, ‘Law, causation and common sense’, Oxford Journal of Legal Studies, Vol. 8, 1988, 111.

[9] J Stapleton, 'Cause-in-fact and the scope of liability for consequences', Law Quarterly Review, Vol. 119, 2003, 388.

[10] Ibid.

[11] Wrongs Act 1958 (Vic), s51(1). See also: Civil Law (Wrongs) Act 2002 (ACT), s45(1); Civil Liability Act 2002 (NSW), s5D(1); Civil Liability Act 2003 (Qld), s11(1); Civil Liability Act 1936 (SA), s34(1); Civil Liability Act 2002 (Tas), s13(1); Civil Liability Act 2002 (WA), s5C(1).

[12] Strong v Woolworths [2012] HCA 5; (2012) 246 CLR 182, [18] (French CJ, Gummow, Crennan and Bell JJ); Adeels Palace Pty Ltd v Moubarak [2009] HCA 48; (2009) 239 CLR 420, [55] (French CJ, Gummow, Hayne, Heydon and Crennan JJ).

[13] Wallace v Kam [2013] HCA 19; (2013) 250 CLR 375, [16] (French CJ, Crennan, Kiefel, Gageler and Keane JJ) (Wallace v Kam).

[14] This limitation was identified by Mason CJ in March v Stramare, at 516.

[15] While this is most clearly unfair when all exposures were caused by negligent defendants (and so but for the negligence of the defendants collectively, the plaintiff would have suffered no harm), it is less clearly unfair when, say, one exposure is negligent and all others are not (as the ‘innocent’ exposures may have been, and in some circumstances will have been likely to have been, sufficient to bring about the disease).

[16] Wrongs Act 1958 (Vic), s51(2).

[17] Booth, [70] (Gummow, Hayne and Crennan JJ) (emphasis added).

[18] [2010] HCA 5; [2010] 240 CLR 111, [65].

[19] Lord Hoffmann, for example, has said extrajudicially, ‘in retrospect, I think we failed this test quite badly...’: Hoffmann, ‘Fairchild and after’ in Judge and Jurist: Essays in Memory of Lord Rodger of Earlsferry (A Burrows, D Johnston, QC, and R Zimmermann eds, OUP, 2013) 65.

[20] Overseas Tankship (UK) Ltd v Morts Dock and Engineering Co Ltd [1961] UKPC 1; [1961] AC 388 (PC) (better known as ‘The Wagon Mound (No 1)’).

[21] Wallace v Kam, [39].

[22] South Australia Asset Management Corp v York Montague Ltd [1996] UKHL 10; [1997] AC 191 (HL), 213.

[23] Ruddock v Taylor (2003) NSWLR 269, [89].


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