Hand formula

The Hand formula, also known as the Hand rule, calculus of negligence, or BPL formula, is a conceptual formula created by United States Judge Learned Hand, which describes a process for determining whether a legal duty of care has been breached (constituting negligence). The original description of the calculus was in United States v. Carroll Towing Co., in which an improperly secured barge had drifted away from a pier and caused damage to several other boats.