The judiciary consists of a Supreme Court, a Supreme Judicial Council, and lower courts. The chief justice and the prosecutor general must be specialists in Shiʿi canon law who have attained the status of mujtahid. Under the 1979 constitution all judges must base their decisions on the sharia (Islamic law). In 1982 the Supreme Court struck down any portion of the law codes of the deposed monarchy that did not conform with the sharia. In 1983 the Majles revised the penal code and instituted a system that embraced the form and content of Islamic law. This code implemented a series of traditional punishments, including retributions (Arabic qiṣāṣ) for murder and other violent crimes—wherein the nearest relative of a murdered party may, if the court approves, take the life of the killer. Violent corporal punishments, including execution, are now the required form of chastisement for a wide range of crimes, ranging from adultery to alcohol consumption. With the number of clergy within the judiciary growing since the revolution, the state in 1987 implemented a special court outside of the regular judiciary to try members of the clergy accused of crimes.

Political process

Under the constitution, elections are to be held at least every four years, supervised by the Council of Guardians. Suffrage is universal, and the minimum voting age is 18. All important matters are subject to referenda.

Political parties are quite numerous but institutionally weak. The constitution guarantees freedom of association but does not permit parties that oppose the existing system of government or the state ideology that underlies it. The Ministry of Interior approves and regulates party activities according to statute. The role of political parties in the political process has been relatively minor since the 1980s. The Islamic Republic Party became the ruling political party at the outset of postrevolutionary Iran, but it subsequently proved to be too volatile, and Khomeini ordered it disbanded in 1987. The Muslim People’s Republic Party, which once claimed more than three million members, and its leader, Ayatollah Mohammad Kazem Shariat-Madari, opposed many of Khomeini’s reforms and the ruling party’s tactics in the early period of the Islamic republic, but in 1981 it too was ordered to dissolve. The government likewise outlawed several early opposition parties, such as the Tūdeh (“Masses”) Party, the Mojāhedīn-e Khalq (“Holy Warriors for the People”) Party, and the Democratic Party of Iranian Kurdistan.

In the absence of any strong political parties, elections center on personalities, who are generally regarded as belonging to one of three ideological camps. Principlists (uṣūl-garāyān; also called “conservatives”) profess dedication to the principles of the Islamic revolution, including the need to safeguard Iranians from corrupting and foreign influences. Reformists (eslāḥ-ṭalabān) seek to liberalize the political system and take a more cooperative approach toward international relations. Political figures who do not fit neatly into either camp are often regarded as “centrists” or “moderates.”

The sidelining of reformists during the presidency of Mahmoud Ahmadinejad (2005–13) and of centrists after the presidency of Hassan Rouhani (2013–21) left the conservatives with almost unfettered power in the 2020s. Factions among the conservatives then jockeyed for dominance, and the fundamentalist Paydari Front (Jebheh-ye Pāydāri-ye Enqelāb-e Eslāmī, “Front of Steadfastness of the Islamic Revolution”) challenged a weakened faction of establishment figures.