議會制
In parliamentary systems, the executive is responsible to the elected legislature, i.e. must maintain the confidence of the legislature (or one part of it, if bicameral). In certain circumstances (varying by state), the legislature can express its lack of confidence in the executive, which causes either a change in governing party or group of parties or a general election. Parliamentary systems have a head of government (who leads the executive, often called ministers) normally distinct from the head of state (who continues through governmental and electoral changes). In the Westminster type of parliamentary system, the principle of separation of powers is not as entrenched as in some others. Members of the executive (ministers), are also members of the legislature, and hence play an important part in both the writing and enforcing of law.