Where a defendant alleges that part of a plaintiff's disability or loss is caused by some unrelated condition or event, it's for the defendant to prove the extent of the loss suffered by the plaintiff as a consequence of that unrelated condition or event and when she would have suffered that loss.
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The law says that insofar as there needs to be some disentanglement of the conditions or injuries suffered by the plaintiff leading to her disability or inability to work, it's for the defendant to prove on the evidence that the plaintiff would have suffered such loss or disability by reason of that unrelated condition, illness or circumstance, so that insofar as the defendant might say to you ... 'well look, she had pre-existing degenerative changes in her back - that increases as one ages'. You heard that evidence from a number of doctors. She may well not have been able to work past December 2006, or some time between now and then, in any event. What the law says is if that's the defendant's case it bears an evidentiary onus of establishing that that was the case to your satisfaction.
Likewise, if the defendant says, 'well, look, this thrombocytosis or the carpal tunnel condition, let's lump them all together - polyarthritis condition - she may not have been able to work past December 2006, or much longer, in any event, regardless of our negligence', assuming you were to find such negligence on the part of the defendant, and what the law says is that where the defendant makes that allegation or puts that up as an answer to the plaintiff's claim or part of it, then it bears the evidentiary onus of showing that that was likely to be so.
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Now, I direct you that insofar as that issue [degenerative changes] is concerned, whether the pre-existing degenerative change would have been likely to have interfered with her capacity to work up until the present time, that it is the defendant who carries the onus of showing that.
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Now [Mr Klug] was never taken by either [counsel] to the extent or the severity of the pre-existing back pain. So it seems that the evidence before you is that there is simply a risk that that might have occurred, but no more evidence. Likewise in relation to the other unrelated illnesses or conditions, the thrombocytosis and the carpal tunnel syndrome, there is no evidence that I can recall before you to the effect that those conditions would have interfered with her ability to work on until the present time.
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When it comes to assessing any future loss of earning capacity that you may get to consider or you may not, but if you do the fact that these conditions have been established as having been in play, so to speak, you could certainly take them into account in terms of vicissitudes of life that might affect [the appellant].