A look at the leadership structure and powers in Iran

Supreme Leader Ayatollah Ali Khamenei: The ultimate decision-maker on all major state and religious matters. He appoints all key positions in the ruling theocracy and controls judiciary and Revolutionary Guards. Supporters believe he is incapable of error and answerable only to God.

Guardian Council: Vets all candidates for parliament, president and other elected posts. Power to veto any legislation. Comprised of six Islamic clerics and six legal scholars hand-picked by Khamenei.

Expediency Council: A 32-member unelected group dominated by conservatives and led by former President Akbar Hashemi Rafsanjani. Mediates in disputes between Guardian Council and parliament. Advises supreme leader.

Expert Assembly: A group of 87 Islamic clerics. Constitution says it oversees supreme leader, but actual role is unclear.

President Mohammad Khatami: Highest elected leader. Leads most aspects of government, but important decisions need backing of supreme leader. Khatami's second and final term expires in 2005.

Parliament: Structured as Western-style legislative branch, but all key measures by 290-seat chamber must have the backing of supreme leader. Main powers in setting budget and other fiscal matters. Law makers have four-year terms.