He gained the university’s silver medal for Greek at both public examinations. In 1907 he was Rhodes scholar for Queensland. Macrossan passed the Barristers’ Board examinations and was admitted to the Bar on 27 August 1912 and subsequently served as Judge, Supreme Court of Queensland (1940), Senior Puisne Judge, Supreme Court of Queensland (1940-1946), Acting Chief Justice, Supreme Court of Queensland (1944-1945), Acting Chief Justice, Supreme Court of Queensland (1945-1946) and Chief Justice, Supreme Court of Queensland (1946-1955).