By virtue of his being an infallible leader and authoritative interpreter of Islamic revelation through his designation to exercise al-wilayat al-tasarruf, the Imam is the sole legitimate authority who could establish the Islamic public order. However, as historical circumstances unfolded, the Imamate became divided into temporal and spiritual spheres. The temporal authority of the Imam was regarded as having been usurped by the ruling dynasty, but the spiritual authority remained intact in the Imam who was regarded as Allah's (unanswerable) demonstration (of divine omnipotence) - Hullat Allah (lit. the proof of Allah), empowered to guide the spiritual lives of his adherents as the true Imam. This spiritual authority was not contingent upon the Imam's being invested as the ruling authority (sultan) of the Ummah. Accordingly, the Imamate in the form of religious leadership that began with the Prophet's proclamation about the wilaya of Imam Ali at Ghadir Khum in 632 AD continued through all the political circumstances until the last Imam, the Twelfth Imam al-Mahdi, went into occultation (874 AD). It was during this period that questions regarding Imami political authority during the absence of the Imam began to be treated methodically, especially when, for the first time, following the last manifest Imamate of Imam Ali (656-660 AD), the temporal authority of the Shia Imami Buyid dynasty was established de facto.
In view of the prolonged occultation of the Imam and the absence of special designation during this period, the Shi`i scholars in their works on jurisprudence reemphasized the separation between power (which could exact or enforce obedience) and wilaya (authority, which reserved the right to demand obedience, depending on legal-rational circumstances) that had existed even during the lifetime of the Imams. Only the investiture of authority and the assuming of political power could establish the rule of justice and equity.
However, delegation of the Imam's wilaya to an individual who
could assume both the authority and power of the Imam when the Imam in occultation could not monitor the exercise of that authority was dangerous. This danger was perceived by some jurists, who, pending the return of the Twelfth Imam, ruled out the possibility of absolute claim to political power and authority (wilaya) resembling that of the Imam himself. Nevertheless, the rational need to exercise authority in order to manage the affairs of the Ummah was recognized and authoritatively legalized. The establishment of the Shia dynasties during the occultation did not change the basic doctrine of the Imami leadership whose direction was set on the occasion of Ghadir Khum by the Prophet.