Born in Rockhampton, he was educated at Downlands College in Queensland (BA and LLB) and in 1951 he was admitted to the Queensland Bar. Sir Gerard was appointed a QC in Queensland in 1965 and subsequently in New South Wales, Northern Territory, Papua New Guinea and Fiji. Although his practice was based in Brisbane, he was senior counsel for the Alliance Party in Lord Denning's arbitration in Fiji Sugar Industry in 1969; in 1972, senior prosecutor in the long-running trial for the murder of the District Commissioner in Rabaul, Papua New Guinea; and, in 1974, senior counsel for the Northern Land Council in the Woodward Commission into Aboriginal Land Rights in the Northern Territory.
He was President of the Bar association of Queensland 1974 - 1976 and of the Australian Bar Association 1975 - 1976 and a member of the Executive of the Law Council of Australia 1974 - 1976. In 1975 he was a part-time member of the Australian Law Reform Commission, retiring in 1977.
He was the first President of the Administrative Appeals Tribunal in 1976, at which time he also served as a Judge of the Australian Industrial Court and an additional Judge of the Supreme Courts of the Australian Capital Territory and of the Northern Territory.
Sir Gerard has variously been Judge of the Hong Kong Court of Final Appeal (2000), and External Judge of the Supreme Court of Fiji (1999 - 2000), Chancellor of the University of Technology, Sydney (1999 - 2005) and Foundation Scientia Professor of Law at the University of New South Wales (1998). He has been an Honorary Visiting Professor of Law at UNSW. In Hong Kong, he is known by a Chinese name (布仁立爵士, bù rén lì jué shì).
Sir Gerard was created a Knight Commander of the Order of the British Empire in 1981, and a Companion of the Order of Australia in 1988. He has been awarded honorary degrees by the University of Melbourne (Hon LLD), University of Technology, Sydney (Hon LLD), University of Queensland (Hon LLD), Griffith University (Hon Duniv), Central Queensland University (Hon Dlitt) and Trinity College, Dublin (Hon LLD).