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Collie, Alex --- "A tangled web of causation in psychiatric injury claims" [2020] PrecedentAULA 19; (2020) 157 Precedent 30

A TANGLED WEB OF CAUSATION IN PSYCHIATRIC INJURY CLAIMS

By Alex Collie

The need to prove causation – that the harm and loss suffered by a claimant was caused by the defendant(s) – is an integral part of any claim in tort. In claims involving a physical injury, identifying the specific event that caused the injury (say, the collision of a vehicle or an object falling) is usually relatively straightforward. However, in matters involving psychiatric injury, the underlying causes of the injury can be unclear. This is particularly the case where a person has experienced multiple traumatic events or stressors.

It is not uncommon, in cases where compensation is sought for psychiatric injuries suffered by children who have been abused in institutional care settings, that the children will also have experienced other traumatic events during their lifetimes: as a consequence of the circumstances that led to them being placed in care; due to their previous experiences in other institutional settings; or through the usual vicissitudes of life. These additional causes, with potentially different degrees of influence, will result in the apportionment of liability between different tortfeasors and/or the reduction of damages to reflect any non-compensable causes.

THE HIGH COURT’S APPROACH TO INJURIES WITH MULTIPLE CAUSES

The High Court decision in Watts v Rake^[1] sets out the main principles that apply when dealing with independent causes of loss. In this case, the plaintiff sought compensation for injuries he suffered in a motor vehicle accident: osteoarthritis and rheumatoid arthritis. Medical evidence, however, suggested that due to the plaintiff’s pre-existing condition of ankylosing spondylitis, he would likely have experienced those same conditions even if the accident had not occurred, albeit at a slower rate.

According to Dixon CJ in Watts, while the plaintiff bore the onus of proving that there had been a change in his condition before and after the accident, the onus then shifted to the defendant ‘who should be required to do the disentangling and to exclude the operation of the accident as a contributory cause’.^[2]

This approach was later followed in Purkess v Crittenden,^[3] where Barwick CJ, Kitto and Taylor JJ confirmed that if a defendant wishes to rely on some other cause of the injury then the defendant has the burden of adducing the evidence to establish that other cause. The extent of the defendant’s evidentiary burden requires the defendant to do more than ‘merely ... suggest the existence of a progressive pre-existing condition in the plaintiff or a relationship between the plaintiff’s present incapacity’ – this pre-existing condition and its relationship to the injury must be the subject of substantive evidence. The evidence must establish the plaintiff’s hypothetical trajectory due to the other cause with a ‘reasonable measure of precision’. In cases of psychiatric injury, this would require the difficult process of an expert successfully disentangling various causes from their pathological results.

The High Court adopted a different approach in Malec v JC Hutton Pty Ltd,^[4] where the defendant was found liable for causing the plaintiff to contract a bacterial disease, which had possible sequelae including depressive illness and a spinal condition. The Full Court of the Supreme Court of Queensland found that the bacterial disease caused the depressive illness but not the spinal condition. The majority held that it was likely that the spinal condition would have caused the depressive illness in any event, preventing the plaintiff from claiming economic loss damages after the spinal condition had developed.^[5]

On appeal, the High Court disagreed with the Full Court’s finding that the ‘likelihood’ the plaintiff would have developed the depressive disease in any event prevented him from claiming damages following the development of the spinal condition. A majority of the High Court held that the plaintiff’s damages should be reduced to reflect the degree of probability that the independent cause would have reduced the plaintiff’s employment capacity. Given that the Full Court majority said that the plaintiff’s depression was ‘likely’ to have been caused by his spinal condition, this suggested that the probability of this being the cause lay somewhere between 51 per cent and 99 per cent.^[6] The assessment of damages was referred to a Master of the Supreme Court for determination.^[7] Justices Brennan and Dawson, while agreeing with the majority’s decision, expressed concern about damages being evaluated in terms of percentages.^[8]

THE DIFFICULTY IN DISENTANGLING PSYCHIATRIC INJURY

For the most part, irrespective of whether an injury is psychiatric or physical, the way in which a court approaches multiple causes will be similar. Malec, by way of example, involved the interplay between a pathogenic vector, a physical injury and a psychiatric illness. Where multiple causes (one of which being the alleged tort) have contributed or potentially contributed to a claimant’s psychiatric injury, the principles set out in Watts and Purkess require a defendant to raise some substantive evidence establishing that the other factors caused (in whole or part) the injury.

Studies show that where a person experiences additional traumatic or stressful events, their symptoms of post-traumatic stress disorder (PTSD) and depression will be more severe.^[9] The difficult task for defendants is to lead evidence that can effectively disentangle these multiple causative factors to quantify what contribution each has had to the claimant’s injury presentation. If a defendant cannot successfully disentangle the causes, then the defendant will be responsible for the full extent of damages.

This outcome was demonstrated in JMD v GJH,^[10] which involved a claim arising out of the alleged sexual assaults of the plaintiff (as a 14-year-old) by the defendant, an acquaintance of the plaintiff’s mother. The claim further alleged ongoing harassment and intimidation by the defendant in the form of letters, emails, text messages, flowers and gifts sent to the plaintiff. A summary judgment was ordered in favour of the plaintiff in respect of the sexual assaults, however, the harassment and intimidation claims proceeded to trial, along with the assessment of damages.

During the trial, the defendant sought to distinguish between the loss and damage caused by the sexual offending and that relating to the harassment and intimidation.^[11] Although the defendant did not call any medical evidence at the trial, the plaintiff’s medical expert, a psychiatrist, was cross-examined. During cross-examination, the psychiatrist was asked whether the intimidation and harassment were the dominant causes of the plaintiff’s distress rather than the sexual assaults. The psychiatrist stated that ‘in my opinion, you can’t disentangle them’.^[12] As a result, despite the harassment and intimidation claims not succeeding, the amount of damages was not reduced.^[13]

Successfully disentangling different causes of a psychiatric injury is often difficult, particularly where the different causes are related or the causative events occurred closely in time. Cunningham v Traynor^[14] was a highly publicised case involving a claim by two persons who alleged that they had been wrongly detained by police, tasered, arrested and held at a police station. Both were later charged with the offence of obstructing a public officer in the performance of the officer’s functions, although these charges were later dismissed following a trial. The defendants included the three police officers who were involved in the arrest, one of whom was also involved in the later prosecution, as well as the state of WA.

Both plaintiffs were found to have developed PTSD as a result of the events that occurred during and following the arrest. The difficult task was to disentangle the varying contributions to this condition from the different forms of battery, including both plaintiffs being tasered, the false imprisonment and the subsequent malicious prosecution. Justice Davis opined that on the evidence provided it was ‘impossible’ to disentangle these different mental effects of the events.^[15]

Successful disentanglement – SB and DC v New South Wales

The following two cases are instances where defendants have successfully disentangled different contributions to psychiatric injuries. Both cases involved the state of NSW as a defendant and have similar factual circumstances; involving claims of negligence against the state’s welfare agencies arising out of the alleged sexual assault of the plaintiffs.

In the matter of SB (by her Litigation Guardian) v NSW,^[16] the plaintiff was a ward of the defendant as a child and placed in foster care. During this time she alleged that she was sexually abused by her foster father (although this abuse did not form part of the claim). The plaintiff was later restored to her natural father who she alleged had also sexually abused her. The abuse by her natural father was severe and extensive, taking place over more than ten years and resulting in the birth of two children. The plaintiff alleged that the state was negligent in returning the plaintiff to her natural father in circumstances that resulted in him sexually abusing her.

The state was not found to have been negligent by returning the plaintiff to her natural father as the harm she suffered was not foreseeable, but the state was found to have breached its duty to the plaintiff by not later removing her from her natural father’s care when it should have been reasonably aware of the ongoing abuse she was experiencing. The date of breach was May 1985, given that this was when the plaintiff’s annual review by the relevant department was to occur.

Consideration of causation in this matter raised issues of separating the impacts of the abuse by the foster father and the abuse by the natural father, in addition to an early history of severe maternal neglect. This was considered in respect of multiple psychiatric disorders and conditions including Borderline Personality Disorder (BPD), PTSD, anxiety, depression, panic attacks and agoraphobia.

Evidence was adduced in respect of each of the above conditions and their connection with the maternal neglect, abuse by the foster father, abuse by the natural father before May 1985, and abuse by the natural father after May 1985. The BPD, for example, was shown to have originated in the plaintiff’s early childhood and further developed as a result of the abuse by the foster father, such that it had firmly developed before the plaintiff was returned to her natural father. As such, the development of BPD was not a compensable loss; however, the ‘more florid episodes’ of BPD were related to her natural father’s ongoing abuse and thus any loss due to that exacerbation was to be compensated.^[17]

By contrast, the PTSD was less easily disentangled from either the abuse of the foster father or the natural father, with Redlich J noting that ‘[n]o expert was prepared to exclude either of the periods of abuse as a significant contributory cause.’^[18] Nevertheless, Redlich J did accept the defendant’s submission that the combined impacts of the maternal neglect and abuse from the foster father accounted for some part of the plaintiff’s PTSD.^[19]

In DC v New South Wales,^[20] two sisters had been subjected to ongoing sexual and physical abuse by their stepfather, for which he was later convicted. It was uncontested that the plaintiffs had been abused by their stepfather from 1974 to shortly before 20 April 1983, when the abuse was first notified to the relevant state welfare agency. The plaintiffs’ claim related to the abuse that was alleged to have occurred after the 1983 notification. They argued that the state had breached a statutory duty to notify the police, which would have prevented any abuse after 1983.

The plaintiffs were unsuccessful at first instance,^[21] with Campbell J finding on balance that no further abuse was experienced by the plaintiffs after the 1983 notification. Notwithstanding this finding, Campbell J did set out his views on the quantum of damages. It was uncontested that the state could not be liable for the abuse predating 20 April 1983^[22] and it was found that the impacts of this earlier abuse had to be apportioned out of any total damages to avoid overcompensating the plaintiffs.^[23] Justice Campbell said that the disentanglement required – due to the principles in Watts and Crittenden – was easier in a matter such as this where the independent cause was not simply a case of increasing the susceptibility of injury in a plaintiff, but rather was a significant source of injury in its own right.^[24] It was found in this matter that the best course of action was to apply an ‘across the board’ discount for all heads of damages – that discount figure being 70 per cent – representing the ‘contribution’ of the abuse prior to 1983.

The plaintiffs appealed the decision^[25] on numerous grounds; including the finding that no abuse had occurred after 1983 and that the apportionment of part of the damages was non-compensable. A majority of the NSW Court of Appeal (Ward JA and Sackville AJA, Basten JA dissenting) overturned the earlier decision and found that, on the balance of probabilities, the stepfather did continue to abuse the plaintiffs after the 1983 notification,^[26] overcoming the usual limitations of appellate review due to the nature of the evidence relied upon by the primary judge.^[27]

In respect of the apportionment of damages, the plaintiffs contended that the defendants had not satisfactorily discharged the evidentiary onus required pursuant to Purkess, and thus his Honour had erred in apportioning any damages between compensable and non-compensable causes. In submissions, both parties confirmed that in the event that it was found that the plaintiffs were not to receive 100 per cent of their damages, the split of 30 per cent and 70 per cent between compensable and non-compensable damages was appropriate.^[28]

It was noted that the defendant had not adduced any evidence establishing the apportionment of harm or damage but had ‘certainly adduced evidence establishing that there was another contributing cause to the ultimate harm’, that being the pre-1983 abuse.^[29] The tension between the principles in Watts and Purkess and the method proposed in Malec was identified, and it was determined that while the defendant had not successfully disentangled the relevant causes of harm as required by the former case, it had sufficiently shown a very real chance that the plaintiffs would have developed similar symptoms but for the post-1983 abuse as required by Malec. The Malec approach was considered appropriate by the majority and the overall reduction of each head of damage to 30 per cent was maintained.^[30] Special leave for the matter to be heard in the High Court was granted in respect of unrelated issues; however, that leave was later revoked.^[31]

No choice but to disentangle

The principles set out in Watts and Purkess mean that where the available evidence indicates that the different causes of a psychiatric injury cannot be disentangled from one another, the full amount of damages in respect of the psychiatric injury will be awarded. But what happens in a case that involves multiple defendants, where the separation of different causes is necessary to ensure a fair distribution of liability for damages among tortfeasors?

This issue arose in Cunningham v Traynor^[32] where the Court had to determine the extent to which each of the defendants (three police officers and the state) should be held liable. An equal apportionment of liability would not have been fair given the involvement, and the varying seriousness, of each defendant’s alleged tort. Despite Davis DCJ’s opinion that the relative impacts could not, on the evidence given, be disentangled, she nevertheless was required to engage in this process in order to properly apportion general damages.^[33] Given the lack of expert opinion to guide this decision, common sense and reason is to be employed. Justice Davis considered each of the torts and how they may have affected each plaintiff; for example, the experience of being wrongfully arrested and imprisoned was said to have been particularly embarrassing and stressful for one of the plaintiffs, who was a lawyer.^[34]

This ‘common sense’ approach was applied many years earlier in Paten v Bale,^[35] a case regarding five separate sexual assaults that were committed by the defendant against the plaintiff, a family friend, when she was eight years old, for which he was convicted. Justice Wilson was required to apportion general damages in respect of each of the five assaults. In doing so, she noted that the evidence available ‘scarcely distinguishes between the incidents’^[36] and that there was no helpful Australian case law upon which to rely.^[37] Instead, a ‘broad and commonsense approach’^[38] was adopted and it was found that the initial assault would have resulted in the greatest injury to the plaintiff (amounting to 80 per cent), with each subsequent assault resulting in an aggravation of the initial injury (amounting to 5 per cent for each).^[39] It is noted that the judges in Cunningham v Traynor and Paten v Bale both employed the common judicial refrain – ‘doing the best I can ...’ – to indicate the limited guidance available.^[40]

CONCLUSION

The threshold required to prove independent causation differs depending on whether preference is given to the requirement to disentangle in Watts and Purkess or the method of calculating risk proposed in Malec. Defendants in matters involving psychiatric injuries will find it much easier to produce evidence of any difference in risk than to produce evidence that disentangles the causes of a plaintiff’s psychiatric presentation. In any event, defendants must do more than merely note the existence of additional causes; evidence must be adduced as to the specific impact of those causes or the change in a plaintiff’s outcomes based on those causes.

The author wishes to acknowledge the assistance of Martin Slattery, Partner, Carroll & O’Dea Lawyers for his assistance with this article.

Alex Collie is an Associate for Carroll & O’Dea Lawyers, Sydney. EMAIL acollie@codea.com.au.

^[1] [1960] HCA 58; (1960) 108 CLR 158.

^[2] Ibid, [160].

^[3] [1965] HCA 34; (1965) 114 CLR 164, 168.

^[4] (1990) 169 CLR 638.

^[5] Malec v JC Hutton Pty Ltd [1988] QSCFC 152.

^[6] Malec v JC Hutton Pty Ltd (1990) 169 CLR 638, [8].

^[7] Ibid, [12].

^[8] Ibid, [2].

^[9] S Suliman et al, ‘Cumulative effect of multiple trauma on symptoms of posttraumatic stress disorder, anxiety, and depression in adolescents’, Comprehensive Psychiatry, Vol. 50(2), 2009, 121–7.

^[10] (2012) 79 SR(WA) 259.

^[11] Ibid, [110].

^[12] Ibid, [113].

^[13] Ibid, [114]. It is noted that in any event, the defendant was found liable for both the harassment and sexual assaults.

^[14] [2016] WADC 168.

^[15] Ibid, [902], [1069].

^[16] [2004] VSC 514; (2004) 13 VR 527.

^[17] Ibid, [581].

^[18] Ibid, [583].

^[19] Ibid, [584].

^[20] [2016] NSWCA 198.

^[21] TB v State of New South Wales and Quinn; DC v State of New South Wales and Quinn [2015] NSWSC 575.