Often plaintiffs either have pre-existing health conditions or have suffered non-work related health conditions by the time of trial resulting in the defendant seeking a discount of damages to account for the effect of the non-work related condition. This is especially so in the case of psychiatric conditions which are often considered to be multi factorial in origin. In White v Hertz Australia Pty Ltd  QSC 82, Daubney J considered in detail, the evidentiary burden to be discharged by the defendant in order for such a discount to be applied.
The plaintiff was a car detailer who sustained a needlestick injury when removing rubbish from a car and then developed a psychiatric injury due largely to the fear he had contracted a blood borne illness. Three months after the injury, he was clear of having contracted such an illness but he continued to experience psychiatric symptoms which increased over time culminating in his admission as a psychiatric inpatient.
At trial, the defendant employer alleged the plaintiff’s work related psychiatric condition ceased after the blood test results were conveyed to the plaintiff and that after that time the psychiatric condition was maintained by other factors including:
- ongoing shoulder pain from a different injury;
- ongoing wrist pain from a different injury;
- workplace interpersonal issues;
- loss of employment; and
- relationship breakdown.
The defendant therefore contended a discount of the damages should be made to reflect the contribution of the non-work related factors to the plaintiff’s loss and damage.
First, the plaintiff must establish that the defendant’s negligence caused the relevant injury. Here, the defendant conceded negligence in relation to the needlestick injury and the causal link between that injury and the psychiatric condition, albeit for a limited period. The evidential burden then falls on the defendant to establish that, had there been no negligence, the plaintiff would have suffered disability from the non-work related condition/s. If this is established, the court can then make a comparison between the plaintiff’s current position and the possible position, but for the negligence.
In considering the medical evidence, Daubney J found:
- the plaintiff suffered a mental disorder as a result of the needlstick injury and that disorder was continuous from that time on;
- having suffered the mental disorder, the plaintiff was more vulnerable to being adversely affected by other life stressors;
- even if the severe shoulder pain contributed to a deterioration of the plaintiff’s mental condition, it did not completely supplant the ongoing effect of the original mental condition;
- even if the negligence had not occurred, the ongoing shoulder pain was of such a severity that it would of itself more likely than not have caused the plaintiff to suffer a degree of mental decompensation;
- he was not persuaded by the medical evidence that the wrist pain or relationship breakdown adversely affected the plaintiff’s mental health;
- it was not established that the “interpersonal issues” at work did any more than contribute to the original condition; and
- there was nothing in the evidence to suggest that the plaintiff’s resignation in itself contributed to his mental disorder.
Having made those findings, Daubney J applied a 50% discount to the past and future economic loss awards to reflect the likelihood of the plaintiff suffering mental decompensation as a consequence of his pre-existing shoulder condition. He also applied a discount to future expenses by way of global allowance.
Although the defendant was unable to demonstrate that the entirety of the plaintiff’s ongoing disability related solely to the pre-existing shoulder condition, they were successful in obtaining a very substantial discount to the damages to reflect the effect of the shoulder condition.
In order to obtain a discount in these circumstances, a defendant must prove:
- the existence of the non-work related condition, that is a diagnosable condition not related to the plaintiff’s work; and
- the possible consequences of the non-work related condition. In this regard, the evidence must be such that a reasonable person having considered the evidence of the non-work related condition could draw the inferences about the condition’s consequences contended for by the defendant.