In 1979, following the overthrow of the Shah, he played a pivotal role in instituting Iran's new constitution. He was one of the leaders of the movement to replace the democratic and secular draft constitution proposed for the Islamic Republic with one where the supervision of Islamic jurists was recognized. He distributed "a detailed commentary and alternate draft" for Iran's new constitution. It included proposals to specify that Twelver Shi'ism—and not Islam in general—was the official religion of the state and to state that Islamic jurists should appoint judges with the right of veto over all laws and actions that are against the Islamic principles. Later he served on the Assembly of Experts ("Majles-e-Khobregan") that wrote the constitution and that implemented many of his proposals.