The role of Supreme Leader in the constitution is based on the ideas of Ayatollah Khomeini, who positioned the leader at the top of Iran's political power structure.

The Supreme Leader, currently Ayatollah Ali Khamenei, appoints the head of the judiciary, six of the members of the powerful Guardian Council, the commanders of all the armed forces, Friday prayer leaders and the head of radio and TV. He also confirms the president's election. The Leader is chosen by the clerics who make up the Assembly of Experts.

Periodic tension between the office of the Leader and the office of the president has often been the source of political instability. It increased during former president reformist Mohammad Khatami's term in office - a reflection of the deeper tensions between religious rule and the democratic aspirations of many Iranians.