During the Iranian Constitutional Revolution (1906-1911) Iranians took part in a national debate over whether or not a constitution and a consultative assembly would free them from years of monarchical absolutism and a judiciary system that was grounded in Islamic law [sharia‘] in the hands of Shi‘ite clerics. They wished to free themselves from years of injustice and corruption that supposedly kept Iranians from attaining meaningful liberty and prosperity. Among Constitutionalists, a number of Shi‘ite clerics participated in this discourse which at a glance seem to have been unlikely allies. Mullah Muhammad Kazim Khurasani, the highest-ranking Shi‘ite leader in Najaf at the time who led the clerics, supported the constitution and the parliament by grounding his argument on freedoms that the interpretation of Islamic jurisprudence [fiqh] granted him. Careful not to violate any Islamic value or doctrine, Khurasani supported the Constitutionalists despite opposition from some prominent clerics. He based his argument on the fact that Iranians needed such change, if they were to prosper in the future. He viewed his support as part of his role as a Source of Imitation [marja‘] for many Iranians. That’s what the twelve Shi‘ite imams would have done, he argued, and since he represented the twelfth imam (al-mahdi, who was in hiding only to return at the end of time), he was obligated to protect the rights of the people by supporting new ventures that would improve their conditions. In offering such conclusion for the first time, in addition to the standard scholarship on the era, I examine Khurasani’s Sufficiency of Principles [Kifayat al-usul] (in Arabic), a seminary text that is still taught as part of the seminary curriculum, and his letters (in Persian) to the Qajar royalty including the crown prince, Muhammad Ali (1902), and subsequent letters to Muzaffar al-din Shah until 1907 in addition to correspondents to other constitutional and anti-constitutional leaders, including Fazlullah Nuri and Ayatullahs Bihbahani (the two brothers); and to the Parliament. Through examining and comparing his jurisprudential writings with his political prose addressed to different groups before and during the Constitutional Revolution, this study suggests that a) Khurasani was a pivotal character in success of the Revolution, and, b) he succeeded in his endeavor by not violating Islamic values, but pragmatically interpreting specifically Iranian Shi‘ite doctrines which deemed it necessary for him as a source of imitation to support Iranians in their efforts of establishing these essential institutions.