Barton was chosen as the Speaker of the New South Wales Legislative Assembly in 1883. He served as the speaker until 1887. In 1891, he was a member of the committee writing the Constitution of Australia. In 1900, he led a group of Australians to London to present the country's first Constitution to the British Parliament. Barton was elected as Australia's first Prime Minister on 1 January 1901, when the new constitution went into effect. He also served as the Minister External Affairs (foreign policy and international relations). He resigned on 24 September 1903, and became a senior judge in the new High Court of Australia, and held that position until his death in 1920. 