Geektastic: It is a very long time now since I studied law as part of my degree - and a reasonable while since I had any need to put that knowledge to use - but IIRC there was a case (Smith v Leech Brain & Co I think) which established the doctrine known as 'Eggshell Thin Skull' in tort and in criminal cases.
It holds that a tortfeasor must take their victim 'as they find them' and that means they are liable for the extent of injuries even where they are greater than what might be expected given normal circumstances.
Now, this is UK law and precedent but I have seen UK cases referred to in NZ court judgments before, so clearly they are relevant in some way. Without actually reading the judgment in full, I have no idea what was argued in court or whether the judge referenced the doctrine but discounted it for some reason.
Overall, I find judges in NZ to be unduly lenient, however, and far too willing to accept excuses.
Excellent post with some actual legal basis for a conclusion - I have never heard of the eggshell skull, but having read wikipedia on it - it is very interesting.
Assuming the principle is held in NZ, and since its from UK law I would think it would - how come it doesnt appear to have been applied in this case?