Calculus of Negligence - Articulation of The Rule

Articulation of The Rule

Hand stated:

he owner's duty, as in other similar situations, to provide against resulting injuries is a function of three variables: (1) The probability that she will break away; (2) the gravity of the resulting injury, if she does; (3) the burden of adequate precautions.

This relationship has been formalized by the law and economics school as such: an act is in breach of the duty of care if:

where B is the cost (burden) of taking precautions, and P is the probability of loss (L). L is the gravity of loss. The product of P x L must be a greater amount than B to create a duty of due care for the defendant.