This encyclopedia entry is about the relationships between judges and rulers in Medieval Islam. In early Islam, the qadi was no more than a legal official under the ruler's supreme judicial power. Between the eighth and the tenth centuries, as Islamic law developed into a specific field governed by legal scholars, the qadis were increasingly identified with a religious jurisdiction that necessarily had to escape from under the authority of the ruler. Therefore, two sets of judicial institutions developed, which came to complement and sometimes compete with each other. For a ruler who needed to govern according to the public interest, to ensure security beyond the prescriptions of the Shari'ah, or simply to serve state interests, it was necessary to rely on institutions that were not bound by the strict prescriptions of Islamic law and could be monitored more easily.