Negligence per se is a common-law doctrine, most developed in U.S. and other Anglo-American tort systems, under which a defendant who violates a statute, ordinance, or regulation is deemed to have breached the standard of care owed to the plaintiff—without the jury having to independently weigh what a "reasonable person" would have done. The plaintiff still must prove causation and damages, but the duty and breach elements collapse into the fact of the statutory violation.
For the doctrine to apply, courts typically require that:
- The statute was designed to protect a class of persons that includes the plaintiff.
- The harm suffered is of the type the statute was intended to prevent.
- The violation proximately caused the injury.
- The plaintiff is within the zone of risk the legislature contemplated.
These criteria are reflected in the Restatement (Second) of Torts § 286 and were articulated in influential opinions such as Judge Cardozo's in Martin v. Herzog, 126 N.E. 814 (N.Y. 1920), where driving without lights at night, in violation of a statute, was held to be negligence as a matter of law rather than mere evidence of negligence.
Jurisdictions differ on the doctrine's strength. Some treat the statutory violation as conclusive of breach; others, following the Restatement (Third) of Torts: Liability for Physical and Emotional Harm § 14, treat it as creating a rebuttable presumption; still others—a minority—regard it only as evidence of negligence to be weighed by the jury. Recognized excuses include incapacity, emergency, or where compliance would itself be more dangerous.
The doctrine is most commonly invoked in traffic-accident cases, building-code violations, workplace safety claims, and pharmaceutical or food-labeling suits. It is not generally available where the statute provides its own exclusive remedy, where it creates no private right of action by implication, or where the legislature explicitly disclaims civil liability. Criminal statutes, licensing requirements, and purely administrative rules are treated unevenly across states.
Example
In *Martin v. Herzog* (1920), the New York Court of Appeals, in an opinion by Judge Benjamin Cardozo, held that a buggy driver's failure to use headlights as required by statute constituted negligence per se in a collision suit.
Frequently asked questions
In ordinary negligence, the jury decides whether the defendant's conduct fell below the reasonable-person standard. In negligence per se, a statutory violation supplies the standard of care, so duty and breach are established by the violation itself.
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