In Shi'a Islam the guidance of clergy and keeping such a structure holds a great importance. The clergy structure depends on the branch of Shi'ism is being referred to. Twelver Usooli and Akhbari Shia Twelver Muslims believe that the study of Islamic literature is a continual process, and is necessary for identifying all of God's laws. Twelver Shia Muslims believe that the process of finding God's laws from the available Islamic literature will facilitate in dealing with any circumstance. They believe that they can interpret the Qur'an and the Twelver Shi'a traditions with the same authority as their predecessors. This process of ijtihad has provided a means to deal with current issues from an Islamic perspective. Generally, clergy in Twelver Shi'a have exerted much more authority in their religious community than the Sunni ulema in theirs. Usooli Shia considering it obligatory to obey a mujtahid when seeking to determine Islamically correct behavior. They believe the 12th Imam, ordered them to follow the scholars (Fuqaha) who: "...guard their soul, protect their religion, and follow the commandments of their master (Allah)..." The mujtahid they follow or emulate is known as a Marja' Taqleedi. As of 2014 there were over 60 recognized Marj in the Shia Muslim world. Historical role in politics and society Modern history The Shia clerics in this period were closely tied with the bazaars that were in turn strongly linked with the artisans and farmers that together formed traditional socioeconomic communities and centers of associational life with Islamic occasions and functions tying them to clerics who interpreted Islamic laws to settle commercial disputes and taxed the well-to-do to provide welfare for devout poorer followers. A succession of prayer-meetings and rituals were organized by both clergy and the laity. Bazaars also enjoyed ties with more modern sectors of Iranians society as many Iranian university students were from the merchant class. But since 1970s, the Shah of Iran aroused the defense and oppositions of the bazaar by attempts at bring under control their autonomous councils and marginalizing the clergy by taking over their educational and welfare activities. This combined with the growing public and clerical dissatisfaction with Shah's secular policies and his reliance on foreign powers particularly the United States, led to a nationwide revolution, that saw a high ranking cleric Ayatollah Khomeini and his clerical disciples as its top leadership, that deposed the Pahlavi Shah and founded the Islamic Republic