Torts
Breach of Duty
Definition
Breach of duty occurs when a person fails to meet the applicable standard of care. Courts use the reasonable person standard — an objective measure of how a person of ordinary prudence would act under the same circumstances. The Hand Formula (B < P x L) is an influential economic approach: a party breaches their duty when the burden of precaution (B) is less than the probability of harm (P) multiplied by the gravity of the harm (L). Custom in an industry is relevant but not dispositive.
Example
A tugboat company fails to keep a bargee aboard during working hours, and its barge breaks free. Judge Learned Hand found the low cost of prevention constituted a breach.