Ordinary negligence asks whether a person acted the way a reasonably careful person would have acted under the same circumstances, and a jury or judge typically has to evaluate the specific facts to decide whether that standard was met.

This standard is flexible by design, allowing courts to account for the specific context of each situation, but it also means the plaintiff has to build a factual case showing exactly how the defendant's conduct fell short.

Negligence per se applies when a defendant violates a specific law or regulation designed to protect public safety, such as a traffic law or building code, and that violation is treated as automatically satisfying the duty and breach elements of a negligence claim.

This shortcut exists because the legislature or regulatory body has already determined that violating the specific rule is unreasonably dangerous, removing the need for a case-by-case reasonableness analysis on that particular point.

Even in a negligence per se case, the plaintiff still generally needs to show that the statutory violation actually caused their injury, and that they were a member of the class of people the statute was intended to protect.

This means negligence per se simplifies part of the case but does not eliminate the need to connect the violation to the specific harm suffered, which remains a separate factual question.

Frequently cited examples include violations of traffic laws that lead to a car accident, building code violations that lead to a structural injury, or violations of specific safety regulations in a workplace setting.

Whether a particular statute supports a negligence per se claim depends on how courts in that jurisdiction have interpreted the statute and whether it was intended to create this kind of civil liability.