The Rt Hon Sir Edmund Barton (1849–1920) was a key player in the federation movement and a leader of the Constitutional Conventions. In September 1903 he resigned as the first Prime Minister of the Australian federation that he had helped to form, to accept a commission as a Justice of the High Court. The Governor-General, Lord Tennyson, signed the commissions appointing Sir Samuel Griffith, Sir Edmund Barton and Richard O’Connor as the first Justices of the Court on 5 October 1903. Bea Maddock's mural outside Court 1 represents the appointments and inauguration ceremony, and Marcus Beilby’s painting on Level 3 depicts the swearing in of Justice Richard O’Connor. Justice Barton sat on the High Court from 5 October 1903 to 7 January 1920.
Edmund Barton graduated with a Bachelor and Masters of Arts degree from the University of Sydney, and studied law in the solicitor’s office of Burton Bradley and G.C. Davis’ chambers. He was admitted to the NSW Bar in 1871. He was appointed a Queen's Counsel (QC) in 1889. He held various parliamentary and executive government appointments during his time as a Member of the NSW Parliament (1879–94, 1897–99), including those of Speaker (1883–87), Attorney-General (1889, 1891–93), Leader of the Opposition (1898–99). In the new Federal Parliament he served as Prime Minister (Protectionist Party) and Minister for External Affairs (1901–03). He was appointed to the Privy Council in 1901 and accepted a knighthood in the Grand Cross of St Michael and St George (GCMG) in 1902, after refusing knighthoods in 1887, 1891 and 1899.