Since the time of the Norman Conquest, the relation between church and state was always tendentious. There were two parallel legal systems, one under the aegis of the church, the other under the crown, that continuously vied for jurisdiction and power. Bracton gave samples of writs that could be used in the case of a recalcitrant Bishop who refused to produce a witness for the common law or king's court. These indicate difficulties in defining jurisdiction, as well as recalcitrance on the part of Church officials to partake in civil and common law matters outside the Church court structure.