The concept of Welayat al Faqih (Authority and Governance of the Jurist) is a long known, well-established and original one in Shiite ideology. With the start of the major occultation in the year 326 hijri great scholars, i.e. Sheikh Saduq (381 H.), Sheikh Mofid (413 H.), Sayyid Murteza (436 H.) and Sheikh Tusi (460 H.), undertook the responsibility of teaching and promoting Islam to the Islamic society in accordance with the needs and circumstances of their time. They effectively sheltered the sacred teachings of Islam before its enemies. Regarding why the implementation of their welayat was not as vast as it is today, it must be said that: before the Islamic Revolution of Iran and in all periods where there was no Islamic Government, religious scholars would apply their welayat in the areas that they had the liberty and freedom to do so. The grounds necessary to execute a vaster sense of welayat were definitely not available for Mirza Shirazi which never gave him the chance to establish an Islamic Government.
The issue of Welayat al-Faqih (authority and governance of the Islamic jurist) has been derived from the core of Islamic teachings of the infallible Imams. With the start of the major occultation in the year 326 A.H. great scholars, i.e. Sheikh Saduq (381 A.H.), Sheikh Mufid (413 A.H.), Sayyid Murteza (436 A.H.), Sheikh Tusi (460 A.H.) undertook the responsibility of teaching and promoting Islam to the Islamic society in accordance with the needs and circumstances of their time. They effectively sheltered the sacred teachings of Islam before its enemies. Ijtihad (the process of making a legal decision by independent interpretation of the legal sources) in fiqh, explication of aqa’id and fundamental beliefs, ethics, history, interpretation of the quran, teaching Islamic sciences, propagating religion, Islamic cultivation of society, purifying the souls of the people and standing against the transgression of colonizers were the most important things they did. In the time of the major occultation, great scholars and faqihs had the responsibility of looking over and supervising the Shiite society. One of the early scholars who undertook this responsibility and whose remarks on wilayat al faqih are still available was Sheikh Mufid (333 or 338 – 413 A.H.). He is one of the renowned faqihs of Shiite history in the fourth and fifth century. His words invariably prove that this great scholar believed in wilayat al faqih and that according to the infallible Imams, in the time of occultation, the faqihs are the ones who must manage and govern the Islamic society. These rich and invaluable remarks still shine even after a thousand years, although some people do not wish to acknowledge it.
After Shiekh Mufid other scholars came along, one after another, discussing and debating about the topic of wilayat al faqih, namely: Sheikh Abu-Salah Halabi (447 A.H.), Ibn Idiris Hili (598 A.H.), Muhaqiq Hili (676 A.H.), Muhaqiq Karaki (940 A.H.), Mawla Ahmad Muqaddas Ardabili (990 A.H.), Jawad bin Muhammad Husseini Ameli (1226 A.H.), Mulla Ahmad Naraqi (1245 A.H.), Mir Fattah Abdulfattah ibn Husseini Maraghi (1266-1274 A.H.), The famous author of Jawahir al-Kalam (1266 A.H.), Sheikh Murteza Ansari (1281 A.H.), Haj Agha Reza Hamadani (1322 A.H.), Sayyid Muhammad Bahr Al-ulum (1326 A.H.), Ayatollah Burujerdi (1382 A.H.), Ayatollah Sheikh Murteza Ha’eri (1362 H.S.) and Imam Khomeini (1368 H.S.).,
Thus the topic of wilayat al faqih is a long known and well established subject in Shiite beliefs.
Regarding whether or not the wali faqih can be more than one person please see Question 1439 (website: 1445) of this website.
As for the reason why the implementation of wilayat by the Faqihs was limited and had a smaller scope before the Islamic Revolution of Iran, we must say: before the Islamic Revolution of Iran and in all periods when there was no Islamic Government, religious scholars would apply their wilayat in areas that they had the liberty and freedom for doing so. This fact is also even true about the Prophet (S.A.) himself and the infallible Imams (A.S.); despite their inherent inner wilayat over the world, in manifesting their wilayah among the people, they were restricted to their jurisdictions and how much the contemporary rulers would allow them without causing them problems and harm.
One of the great faqihs in the history of Islam that has exercised the wilayat is Mirza Shirazi, famous for his fatwa against tobacco by which he used his privileges as Wali Faqih to issue.
Although, without doubt, the necessary grounds didn’t exist at that time and the governing circumstances were not in favor for him to practice his wilayat in a vaster and more open way and maybe establish an Islamic Government.
In conclusion, before the Islamic Revolution of Iran and throughout the history of the Shia, a lot of faqihs such as; Sheikh Tusi, Shiekh Mufid, Sayyid Murteza, Shahid Awwal, Shahid Sani and Allamah Majlesi attested to the validity of wilayat al faqih and exercised it, and since their fatwas were acted upon in different regions and there usually wasn’t any conflict between their fatwas, there were times that more than one faqih would issue an authoritative judgment and verdict in the same country, such is Iran.
 See: Wilayah Faqih and Sheikh Mufid, Question 22 (website: 255).
 See: Wilayah Faqih and the Ulema, Question 23 (website: 256) and Question 24 (website: 257).
 With help from Question 21 (website: 254).
 In al-Lum’ah al-Damishqiyyah, Shahid Thani (The Second Shahid) engages extensively in his fiqhi-political views. We will point to two of those viewpoints:
a) As with Shahid Awwal, Shahid Thani sees judging as the responsibility of the qualified jurist during the occultation of the imam (aj). In their opinion, jurists have the permission to carry out shar’i punishments, given that no other harm is entailed and that they are qualified for issuing fatwas, meaning that they bear: iman (being Shia), idalah (are just) and knowledge of Islamic Law. Also, Shahid Thani believes that it is wajib for the jurist to accept this responsibility, given that he isn't compelled to commit haram in the process, and that he possesses the sway and power to do amr bil maruf wa nahy anil munkar (enjoin good and forbid evil). In this case, it is upon the people to refer to and accept his fatwas and act upon them. This theory encouraged the ulema of that time to accept the judging done by the Safavid dynasty.
b) Shahid Thani was the first jurist to not only say that the Friday Prayer isn't haram or a takhyiri (voluntary) wajib during the occultation of the imam (aj), but to proclaim it being an eyni wajib (wajib upon each and every person). See: Shirudi, Morteza, Andisheye Siyasiye Mosalmanan, pg. 145.
 Shirudi, Morteza, Andisheye Siyasiye Mosalmanan, pg. 148.