Rule or discretion In Islamic central banking

The rule against discretion is a key issue in monetary policy research. There are many studies that each recommends the use of one or a combination of both Islamic Central Banking has not been the exception, now the question is about the Islamic central banking, which one under the ideal assumption and realistic condition is comply with the Islamic teaches, it needs research.
By a definition, the discretion has three completely arbitrary, optimistic, and re-optimal types between the time when the former and the second are not desirable, but the third one has advantages that it can verified against the rule.
This paper by descriptive-analytic method shows that within the framework of an Islamic state with an ideal assumption although re-optimization has the positive points of the rule and it has no weaknesses of that, it is preferable to prefer the rule, but given the institutional characteristics of the central bank, The money authority is not directly chosen by the Vali-e- Faghih and is not monitored by him. According to the existing empirical evidence, the existence of time incompatibility, political business cycles and financial domination in the Iranian economy, from the point of view of the Maslaha of the system, obliges the monetary authority to use an appropriate monetary rule is better in the context of a secondary verdict.