The Reasonable Person’s Response: Calculus of Negligence
Wyong Shire Council v Shirt (1980) 146 CLR at (47-8).
Mason J :
“In deciding whether there has been a breach of the duty of care the tribunal of fact must first ask itself whether a reasonable man in the defendant’s position would have foreseen that his conduct involved a risk of injury to the plaintiff or to class of persons including the plaintiff. If the answer be in the affirmative, it is then for the tribunal of fact to determine what a reasonable man would do by way of response to the risk. The perception of the reasonable man’s response calls for a consideration of the magnitude of the risk and the degree of probability of its occurrence, along with the expense, difficulty and inconvenience of taking alleviating action and any other conflicting responsibilities which the defendant may have. It is only when these matters are balanced out the tribunal of fact can confidently assert what is the standard of response to be ascribed to the reasonable man placed in the defendant’s position.”
Civil Liability Act 2003 (Qld)
(2) In determining whether a reasonable person would have taken precautions against a risk of harm, the court is to consider the following (amongst other relevant things):
a) the probability that the harm would occur if care were not taken,
b) the likely seriousness of the harm,
c) the burden of taking precautions to avoid the risk of harm,
d) the social utility of the activity that creates the risk of harm.
That means that to determine standard of care and whether defendant discharged his or her duty to take care, the probability of the risk happening, and its gravity of it actually happening are measured against the practicability of precautions necessary to reasonably guard against foreseeable risk and the social utility of the defendant’s conduct.