Medieval county administration performed four major functions. It provided the central government with some of its finance; it protected the king's feudal rights and revenues within the shire; it was responsible for providing the military support demanded by the crown and, through its judicial activities, it maintained the king's peace. In the generation following the Conquest, the official most responsible for performing these duties was the sheriff who, unlike his Anglo-Saxon forebear, was drawn from the ranks of the regional magnates, the baronage. The baronial sheriffs were powerful men indeed, occasionally holding the office in a number of shires at once, often treating the shrievalty as an hereditary fief and, at times, using their vice–regal authority to launch rebellions against the crown.

Nevertheless, by the fifteenth century two developments had occurred. First, the powers of the sheriff had been trimmed by the appointment of additional, more specialized, officials. Second, the great baronial families had ceased personally to fill the offices of local government. Instead, these offices had passed to lesser men of gentle status who, for the most part, held lands and lived in the counties where they served. During the Angevin and Plantagenet periods, government became not only local rather than regional but it also became self-government.

The first limitation to the powers of the sheriff came at the end of the twelfth century with the arrival of the coroner whose office, from 1246 onwards, was filled by election for life in the county court.