Australia is a parliamentary constitutional monarchy. A hereditary monarch serves as head of state, while political executive power is exercised by a prime minister and cabinet drawn from or supported by the elected legislature. The monarch's duties are largely constitutional and ceremonial, although the formal powers of the crown vary according to national law and convention.
Legislative authority is exercised through a bicameral national parliament. The two chambers share responsibility for passing laws and approving public finances, with their precise powers and methods of selection defined by the constitution. Parliamentary committees and plenary sessions provide formal mechanisms for scrutiny, while the courts are institutionally separate and may review government action as permitted by law.
Australia is organized on a federal basis, so constitutional authority is divided between national institutions and constituent states, regions, provinces, or other federal units. Those subnational governments have their own legally protected responsibilities, while defense, foreign affairs, national finance, and other sovereign functions remain principally at the federal level. Political authority is exercised through the constitutional institutions described above, with elections, parliamentary confidence, or other constitutional procedures determining who holds office.