The Shah's autocratic rule and his extensive use of the secret police led to widespread popular unrest throughout  1978. The religious-based protests were conservative in nature, directed against the Shah's policies. Imam Khomeini, who was expelled from Iraq in Feb 1978, called for the abdication of the Shah. Martial law was declared for all major cities. As governmental controls faltered, the Shah fled Iran on 16 Ian 1979. Imam Khomeini returned to Iran in 01 Feb 1979 and took over the leadership of religious revolutionaries. The coalition which had united against the monarchy, composed of different social classes each with its own political aims, collapsed as soon as the latter was abolished, leaving two main forces in confrontation: the Army, which the Bakhtiar's government was unable to control; and the clergy. Imam Khomeini's return to Tehran, marks the beginning of the last phase in the formation of an Islamic Government. On 09 February, clashes broke out between the imperial guard and units of the air forces faithful to Imam Khomeini. This was followed by two days of insurrection during which the inhabitants of Tehran took over several strategic buildings in the capital. On 12 February, a provisional Islamic government was named with Mahdi Bazargan as prime minister. The Islamic Republic was proclaimed by Ayatollah Khomeini during the night of01 Apri11979.
For nearly fifteen years following the victory of the Islamic Revolution (11 February 1979) Iran had been going through a period of ordeal in order to take the first steps towards the final establishment of an Islamic government. The basic measures to organize the Islamic system of administration were taken quite soon after the Revolution. But the Islamic Government as it is, took shape gradually over the last few years.
A referendum to decide thetype of regime was held on I April 1979, only 50 days after the revolutionary takeover. According to official reports, 98.2% of the electorate voted for an Islamic Republic in preference to the previous monarchical regime. A draft Constitution was prepared before the summer of 1979 and a 72-member Assembly of Experts approved it after lengthy deliberations. The Constitution was subsequently ratified by the leader of the Islamic Republic, the late Ayatollah Khomeini, as well as by a direct vote on 3 December 1979. This time, according to official sources, 98.5% of the voters cast their votes for the Constitution. The general framework of the Islamic system of government was therefore decided upon, but many details had yet to be worked out.
The first general election on 28 May 1980, and the convening of the first Parliament (Majlis) were the subsequent steps in that direction. Ever sJ.nce, the laws passed by the Maj lis have brought the founders of the Islamic Republic step by step closer to their objectives. Nevertheless, Iranian leaders and officials are unanimous that there is still along way to go to achieve the ultimate goal.
The government's proclaimed aim is to create a fully-fledged Islamic system of government based on the teachings of the Prophet Mohammad and his successors, which has never been in operation anywhere during the 14-century history of Islam. This makes the Iranian government perhaps the only existing example of theocratic government in the late 20th century.
As to the secular aspects of the country's administration, one might say that the new Constitution has followed the Western Democracies and the former regime's Constitution -as far as the separation of the Executive, the Legislative, and the Judiciary powers is concerned.

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