The Guardian Council comprises twelve jurists including six appointed by the Supreme Leader. The others are elected by the Iranian Parliament from among the jurists nominated by the Head of the Judiciary. The Council interprets the constitution and may veto Parliament. If a law is deemed incompatible with the constitution or Sharia (Islamic law), it is referred back to Parliament for revision. The Expediency Council has the authority to mediate disputes between Parliament and the Guardian Council, and serves as an advisory body to the Supreme Leader, making it one of the most powerful governing bodies in the country. Local city councils are elected by public vote to four-year terms in all cities and villages of Iran.