History and role
By 1987, the legislative process as well as the country's long-term policy formation had come to a standstill due to the doctrinal conflict between radical factions of the Islamic Consultative Assembly and the Guardian Council, which officials described as coercive at the time. Consultations in February the following year led to
Ayatollah Khomeini ordering the appointment of a 13-member council that was given legislative authority: it could pass temporary laws (effective for three-year periods). Article 112 of Iran's Constitution states the EDC will be convened by the Supreme Leader to determine expedience cases where the Guardian Council finds an Islamic Consultative Assembly decision against the principles of religious law or the constitution, and where the Consultative Assembly is unable to satisfy the Guardian Council in view of the expedience of the Islamic Republic of Iran. Formally, the Expediency Discernment Council of the System (or Regime) is primarily a constitutional advisory body for the Supreme Leader (at the latter's behest), as described in article 112 of the Islamic Republic's Constitution. It is meant to "discern the interests of the Islamic Republic" by resolving internal regime conflicts.
 The Council consisted of thirteen members when originally convened, and included six clergy members (appointed by the Supreme Leader), six public officials (President, Prime Minister, Majles Speaker, Supreme Court Chief Justice, Prosecutor General, and a Supreme Leader representative), as well as the Majles member whose legislation was overturned. The EDC Chairman is appointed every five years by the Supreme Leader.
 Even though the Supreme Leader is a member of the Council itself (and it being his advisory council), he can deputize the Council. Nine years later, in 1997, Khamenei expanded its membership to thirty-four, twenty-five of whom were thence appointed for five-year terms. During February 2007, a new Council was formed, with twenty-seven members being directly chosen by the Supreme Leader this time.
Among other roles, the Council determines if and when the Supreme Leader can no longer rule because of certain circumstances, such as character flaws. As stated by article 111, if the position of Supreme Leader is undeclared for whatever reason, a council composed of President, head of the Judiciary, and one of the jurisconsults of the Guardian Council chosen by the EDC shall discharge his functions collectively and temporarily. If any of them is unable to discharge his duties, another person shall be appointed by the EDC in his place. The Council also resolves disputes that concern the
Guardian Council and the
Majles. Domestic and foreign policies of the regime are determined only after consultation with the Expediency Council, according to article 110 of the Constitution (with oversight of the Supreme Leader). The Expediency Council is only meant to act on behalf of the legislative branch, althouth in reality it intercedes as a mediator between all bureaucratic branches, including the executive. If ratification of the Consultative Assembly is not confirmed by the Guardian Council (and deputies insist on implementing the ratification), the EDC can intervene to make a decision. The Expediency Discernment Council can advise the
faghih on policy and strategy (in accordance to article 111 of the Constitution), and despite not being part of the legislative branch, it can remove parliamentary powers. As an example of this, in April 2000 it removed from parliamentary capacity the faculty to investigate institutions under the control of the Supreme Leader, such as the
Pasdaran and the Council of the Guardians. In practice, its composition almost guarantees its rulings mirror the legal opinion the Guardian Council, and more importantly, the Supreme Leader's. Being dominated by conservative
ulama, this has furthered the faction's grip over Iran.
During august 2001, the Council was convened by the Supreme Leader to resolve the dispute between the Judiciary and the Assembly. The latter was dominated by reformers, while the former was dominated by conservatives, so the
Ali Khamenei wanted the EDC to settle this political confrontation. The confrontation referred to the parliament's rejection to approve conservative candidates's appointments to the Guardian Council. Conservatives did not want to lose control of the Guardian Council, dreading president
Mohammad Khatami and reformist allies would push through political and social reforms. Members of the Council are generally
hojatolesiams (a step before ayatollah). In 2005, the capacity of the Council to act as a government supervisory body was supplemented to its powers. The EDC's influence grew when cleric
Hashemi Rafsanjani joined it.