William Harrison Moore was an journalist, lawyer and academic. His early career saw him working as a gallery journalist at the British House of Commons, and with the help of a Barstow law scholarship from the Council of Legal Education, he gained entry at King's College at the University of Cambridge in 1887. Moore graduated from Cambridge in 1891 with a Bachelor of Arts degree, and from the University of London with a Bachelor of Laws, winning both the George Long prize and the Chancellor's medal from King's College.
Poor health led Moore to make the decision to immigrate to Australia, and he arrived in 1892 having been appointed to the positions of professor and Dean of the Law School of the University of Melbourne. As an enthusiastic supporter of Federation he studied the various draft constitutions, and by the time of the Second Constitutional Convention in Adelaide in 1897, had become an authority on the area. His first major work, The Constitution of the Commonwealth of Australia (1902) is both an examination of the Constitution of Australia and a history of the Federation movement.
Moore retired from the Melbourne Law School in 1927, and was appointed professor emeritus the following year. Between 1927 and 1930 he was also Australia's delegate to the League of Nations.