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

The adoption of the Constitution of the Commonwealth of Australia marked the formal creation of Australia as a unified nation. Before federation, the Australian continent consisted of six separate British colonies—New South Wales, Victoria, Queensland, South Australia, Western Australia, and Tasmania—each with its own government and laws. During the late nineteenth century, many political leaders and citizens began to support the idea of uniting these colonies under a single federal system. Federation was seen as a way to improve trade, strengthen defense, and develop a shared national identity while still allowing each colony to maintain a level of self-government.

The movement toward federation led to a series of constitutional conventions in the 1890s, where delegates from the colonies met to draft a constitution. These conventions, held in cities such as Adelaide, Sydney, and Melbourne, involved debates over issues like the balance of power between the federal and state governments, representation in parliament, and the structure of the judiciary. Influenced by systems such as the British parliamentary model and aspects of the United States federal system, the delegates produced a document that established a federal parliament, a High Court, and a division of powers between national and state governments.

After the constitution was drafted, it had to be approved by the people of the colonies through a series of referendums held between 1898 and 1900. Most colonies voted in favor of federation, although some required multiple votes before the proposal passed. Once the colonies agreed to unite, the constitution was sent to Britain for approval. The British Parliament passed the Commonwealth of Australia Constitution Act 1900, which incorporated the Australian Constitution and provided the legal authority for the new nation to be formed.

The Constitution officially came into effect on 1 January 1901, when the six colonies became states within the newly established Commonwealth of Australia. This event is known as Australian Federation, and it marked the beginning of Australia as a self-governing nation within the British Empire. The Constitution continues to serve as the foundation of Australia’s political system today, outlining the structure of government, the powers of parliament, and the relationship between the federal government and the states.