Before the 1979 revolution, Iran was an absolute monarchy, with the constitution of 1906 modified by a supplement of 1907 and amendments of 1925, 1949, and 1957. The shah was the chief of state, with sweeping powers. He commanded the armed forces, named the prime minister and all senior officials, and was empowered to dissolve either or both legislative houses. The legislative branch comprised the national assembly (Majlis) and the senate. Members of the Majlis were elected for four-year terms from 268 constituencies by adults 20 years of age and older. Half of the 60 senators were named by the shah, and half were elected. Members of the Majlis ostensibly represented all classes of the nation, while the somewhat more conservative Senate consisted of former cabinet ministers, former high officials, and retired generals.
The constitution of December 1979, which was approved in a public referendum and revised in 1989, established an Islamic republic in conformity with the principles of the Shi'a faith. Guidance of the republic is entrusted to the country's spiritual leader ( faqih) or to a council of religious leaders. An appointed Council of Guardians consists of six religious leaders, who consider all legislation for conformity to Islamic principles, and six Muslim lawyers appointed by the supreme judicial council, who rule on limited questions of constitutionality. In accordance with the constitution, an 86-member Assembly of Experts chooses the country's spiritual leader and may nullify laws that do not conform to Islamic tenets. In 1998, seats on the council (which have eight-year terms) were opened for the first time to nonclerics.
The executive branch consists of a president and council of ministers. The president is elected by popular vote to a four-year term and supervises government administration. Candidates for the presidency and parliament must have the approval of Iran's spiritual leaders. As of 2003, the Majlis consisted of 290 members elected directly to four-year terms. Suffrage is universal for those over age 15.
There were more than 800 candidates for president in 2001, and the Council of Guardians narrowed them to 10. Khatami was the sole moderate, with all of the other candidates having ties to conservative or hard-line parties. On 8 June 2001, Khatami secured 77% of the popular vote, with four-fifths of 43 million eligible voters turning out.