The coup d'état of 14 July 1958 established an autocratic regime headed by the military. Until his execution in February 1963, 'Abd al-Karim al-Qasim ruled Iraq, with a council of state and a cabinet. On 27 July 1958, a fortnight after taking over, Qasim's regime issued a provisional constitution, which has been repeatedly amended to accommodate changes in the status of the Kurdish regions. Since the 1968 coup, the Ba'ath Party ruled Iraq by means of the Revolutionary Command Council, "the supreme governing body of the state," which selected the president and a cabinet composed of military and civilian leaders. The president (Saddam Hussein from 1979–2003) served as chairman of the Revolutionary Command Council, which exercised both executive and legislative powers by decree. He was also prime minister, commander-in-chief of the armed forces, and secretary-general of the Ba'ath Party. A national assembly of 250 members that was elected by universal suffrage in 1980, 1984, 1989, 1996, and 2000, had little real power. Most senior officials were relatives or close associates of Saddam Hussein; nevertheless, their job security was not great.
The precarious nature of working in the regime of Saddam Hussein, even for relatives, was made evident in 1995 when two of his sons-in-law defected to Jordan along with President Hussein's daughters. The defection was widely reported in the international media and considered a great embarrassment to the regime as well as a strong indicator of how brutal and repressive its machinations were. After a promise of amnesty was delivered to the defectors by Iraq, the men returned and were executed shortly after crossing the border into Iraq.
In the aftermath of the Iraq war which began in March 2003, Iraq was effectively ruled by the US-installed Office of Reconstruction and Humanitarian Assistance, and then by a Coalition Provisional Authority. In December 2003, Saddam Hussein was captured and brought into US custody; beginning in October 2005, he went on trial for the killing of 143 Shias from Dujail. In June 2004, sovereignty was transferred back to Iraq and an interim Iraqi government was installed, led by Prime Minister Iyad Allawi. On 30 January 2005, Iraqi voters elected a 275-member Transnational National Assembly. In April 2005, the National Assembly appointed Jalal Talabani, a prominent Kurdish leader, president. Ibrahim al-Jaafari, a Shia, was named prime minister. A constitution was written and presented to the people in a national referendum held on 15 October 2005: more than 63% of eligible voters turned out to vote. The constitution passed with a 78% majority.
Under the 2005 constitution, the government is broken down into four branches: legislative, executive, judicial, and independent associations. In the legislative branch, two councils were created: a Council of Representatives, the main law-making body, and the Council of Union, whose primary task is to examine bills related to regions and provinces. The executive branch is composed of a president, who is not directly elected and whose powers are primarily ceremonial; a deputy president; a prime minister, who as head of government is appointed by the president from the leader of the majority party in the Council of Representatives; and a cabinet chosen by the prime minister. The judiciary is independent and composed of the following: a Supreme Judiciary Council; a Supreme Federal Court; a Federal Cassation Court; a Prosecutor's Office; a Judiciary Inspection Dept.; and other federal courts organized by law. The "fourth branch" is that of independent associations whose actions are subject to legislation and supervision by the other branches. They include: a Supreme Commission for Human Rights; a Supreme Independent Commission for Elections; an Integrity Agency; an Iraqi Central Bank; a Financial Inspection Office; a Media and Communications Agency; Offices of (religious) Endowments; Institution of the Martyrs; and the Federal Public Service Council.
On 15 December 2005, new parliamentary elections were held to elect a permanent government. Sunni Arab parties won 58 of the 275 seats in the Council of Representatives, which was the second-largest bloc of seats. In all, four main coalitions won 250 of the 275 seats in the parliament, which will lead the country until 2009. Of the remaining 25 seats, most were won by smaller groups with ideological or geographic links to the winning coalitions. The United Iraqi Alliance, the alliance of the main Shia parties, took 128 seats. The Kurdistan Alliance, an alliance of the primary Kurdish parties, won 53 seats. The Iraqi Consensus Front, an alliance of predominantly Sunni parties, took 44 seats, and the Iraqi List, an alliance of the main secular parties, won 25 seats.