Latin for “by itself,” in other words, inherently. For example, in tort law, a statutory violation is negligence per se. One of the elements a person has to prove in a negligence claim is that the defendant breached their duty owed. There is a duty to obey the law bound up in the duty to act non-negligently. Violating a statute is by definition a breach of the duty a person has to follow the law. If a defendant violated a statute, the plaintiff does not need to prove the defendant breached their duty because a person inherently breaches this duty when they violate the statute. Violating a statute is negligence per se.
[Last updated in August of 2020 by the Wex Definitions Team]