The constitution sets out the framework for the republic of Singapore, including a President, who is elected every six years, and a Prime Minister. The Prime Minister leads the government and is appointed by the President, but is responsible to the Parliament and must be accepted by it. Singapore's constitution is also based on the Westminster system, which means all ministers must be members of Parliament (MPs). If they, including the Prime Minister, are not elected to Parliament, they cannot remain in their position. The judiciary also has a strong role in the constitution, with judges acting independently of the President, the government and the Parliament. Judges are appointed for a long time, and cannot be removed except for misconduct. The highest court is the Supreme Court of Singapore, which was set up in 1970, five years after the constitution. 