Peace officer

In the broad sense a peace officer is any public sector person charged to uphold the peace. In modern times this refers primarily to police officers, constables, American sheriffs or marshals and their deputies, and their equivalents under various legal and cultural systems, but in olden times the category also included knights, other nobility, and certain judges of first instance (from which derives the term Justice of the Peace).

Modern legal codes use the term "peace officer" as an inclusionary term for every public sector person vested by the legislating state with law enforcement authority. Hence city police officers, county sheriff's deputies, and state troopers are usually vested with the same authority within a given jurisdiction.