legal and evidential burden of demonstrating the causal link between the
breach or wrongful act and the injury.
324
[292] In relation to consecutive causes, and natural causes in particular, Luntz
summarises the position as follows:
325
It is now well established that where the effects of the defendant’s
wrong would have occurred in any event owing to a natural condition
from which the plaintiff was already suffering or which develops
before the trial, the defendant is not liable for these effects, i.e.
casual responsibility is attributed to the natural condition and not the
wrongful act.
[293] Counsel for the respondent has drawn the Court’s attention to a number of
relevant authorities, in particular Queen Elizabeth Hospital v Curtis,
326
where Kourakis J has usefully dealt with a similar issue:
[128] It is not sufficient that a plaintiff prove that the injury was
first discovered after the wrongful conduct. If it is not shown that
the injury occurred after the relevant breach of duty the inductive
force of the reasoning to which I have referred vanishes. At least in
the world as we know it, conduct cannot be the cause of an injury
that precedes it. A plaintiff cannot prove that a breach of duty has
caused the injury for which damages are sought without proving that
he or she did not suffer that injury before the occurrence of the acts
or omissions by which the duty was breached. I accept that a
plaintiff may prove his or her previous good health in a number of
ways. The absence of symptoms, the opinion of a medical
practitioner who has conducted a medical examination prior to the
conduct, or the temporal features of the aetiology of the disease are
the most obvious examples. Less obviously, the previous good
health of the plaintiff might also be established by evidence that the
plaintiff was not previously exposed to any conditions that could
have caused the injury. However, in this case the evidence showed
the very opposite. It showed that the plaintiff had been suffering the
324
Consistent with Watts v Rake (1960) 108 CLR 158.
325
Luntz, Assessment of Damages for Personal Injury and Death at [2.6.4].
326
(2008) 102 SASR 534 at [128], [130].