The constitution of the Islamic Republic of Iran was passed by the assembly of constitution Experts in 1979. It was reviewed by the council for the Revision of the constitution in 1989. In order to answer questions about origins and causes of amending the constitution, and reasons for change in quality of political authority in post-islamic revolutionary Iran s political-legal system, are based on Iranian well-known proposition. Because it seems that contemporary political and social changes of Iran are the result of the challenges between traditionalism and modernity. On the one hand, the need for economic reconstruction after Iraq s eight year war against Iran required concentration of power in the executive branch and a fast dispute settlement mechanism between the three branches of power. Therefore, a review of constitution was a reasonable choice. But the dismissal of Ayatollah Montazeri from his position as the successor of the supreme leader, Sever illness of Imam Khomeini, suitable time that derived from the acceptance of 598 resolution and the end of the Iraq – Iran war, on the other hand, expedited the process of amendment of the constitution of Islamic Republic. The departure of Imam Khomeini caused the emerging a kind of qualitative change in political authority and the legal-Political system. Charismatic authority of Imam Khomeini caused reconciliation between the two paradoxical traditional and Modernist discourses; and brought about the collapse of the Pahlavi dynasty. Extra constitutional Practices and the bypassing of legal institutions performed by Imam Khomeini, could not continue by the new leader Ayatollah Khamenei; because he lacked not only the charisma but also the necessary conditions for being a religious authority. Therefore, there was a change in the structural-functional discourse, and the charismatic authority developed in to a traditional – clerical authority; and then to pseudo – rational and legal authority.

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