The Expediency Council, which Ayatollah Khomeini created in 1988, wields influence through its role as national policy adviser to the supreme leader. The council also mediates legislative disputes between the parliament and the Guardian Council.
Its members include heads of the three government branches, the clerical members of the Guardian Council and various other members appointed by the supreme leader for three-year terms. Cabinet members and parliamentary leaders also serve as temporary members when issues under their jurisdictions are under review.
Sources: U.S. Department of State Background Notes, Iran Chamber Society: "The Structure of Power in Iran," BBC: "Iran: Who Holds the Power?"