Pakistan, formally known as the Islamic Republic of Pakistan, is indeed a multi-party system. Pakistan is a federal republic, with a bicameral (two house) legislature, consisting of the Senate and the National Assembly. Members are elected to the legislature by proportional representation vote. Senators serve 6-year terms, and Assembly members serve 5-year terms. The government is divided into three branches, the Executive, Legislative, and Judicial. The Executive branch consists of the President, who is the chief of state (diplomatic role), and the Prime Minister, who is the head of government (domestic political role). The Judicial branch consists of a high court, called the Supreme Court, and subordinate courts, including a Federal Shariat Court, as Pakistan is governed by both common law and Sharia (Islamic) law. Pakistan has twelve official political parties.