Calculus of negligence refers to a principle used to determine as to whether a legal duty of care has been breached. This principle is usually accepted in the negligence law. The term calculus of negligence was coined by Judge Hand in United States v. Carroll Towing Co., 159 F.2d 169 (2d Cir. N.Y. 1947) In this case the judge observed that “The owner's duty, as in other similar situations, to provide against resulting injuries is a function of three variables:
(1) The probability that s/he will break away;
(2) the gravity of the resulting injury, if s/he does; and
(3) the burden of adequate precautions.”
The term calculus of negligence is also known as hand rule or hand formula.