Al-Hakim co-founded the modern Islamist political movement in Iraq in the 1960s, along with Ayatollah Sayed Mohammed Baqir Al-Sadr, with whom he worked closely until the latter's death in 1980. Though not among the most hard-line of Islamists, Al-Hakim was seen as dangerous by the ruling Baath regime, largely because of his agitation on behalf of Iraq's majority Shia population (the ruling regime was comprised mostly of Sunnis). This led to his arrest in 1972, but he was released shortly thereafter.