Garran had been made a Knight Bachelor in 1917[29] and was appointed as a Knight Commander of the Order of St Michael and St George (KCMG) in 1920.[30] Garran attended two Imperial Conferences, accompanying Prime Minister Stanley Bruce in 1923 and in 1930 joining Prime Minister James Scullin and Attorney-General Frank Brennan, chair of the Drafting Committee which prepared drafts of agreements on various topics, such as merchant shipping. He also attended the eleventh League of Nations conference that year with them in Geneva, Switzerland. At the Royal Commission on the Constitution in 1927, Garran was invited to give evidence by Prime Minister Bruce, where he discussed the history and origins of the Constitution and the evolution of the institutions established under it.