In Melbourne, the representatives of five colonies adopt a constitution, which would become the basis of the Commonwealth of Australia.

The Constitution of Australia, which came into effect on January 1, 1901, is the supreme legal framework that establishes the country’s system of government. It was enacted through the Commonwealth of Australia Constitution Act 1900 (UK) and primarily defines the structure, powers, and functions of the federal government, including the division of powers between the Commonwealth and the states. Australia operates as a constitutional monarchy with a parliamentary democracy, where the British monarch remains the head of state, represented by the Governor-General. The Constitution outlines the roles of the Executive, Legislature, and Judiciary, emphasizing the separation of powers. It also includes provisions for federalism, detailing the responsibilities of the national and state governments. Unlike some constitutions, it lacks a comprehensive Bill of Rights, relying instead on legislation and common law for civil liberties. Constitutional changes require a referendum, following the double majority rule, which demands approval by both a majority of voters nationwide and a majority of states.