James Sands Elliott was born at Randalstown, County Antrim, Ireland, on 28 May 1880, the son of James Kennedy Elliott, a Presbyterian minister, and his wife, Margaret Dickson. When he was four he was brought to Wellington, New Zealand, where his father became minister to the Kent Terrace Presbyterian Church.
Elliott was educated at Wellington College and spent one year at the University of Otago Medical School. His father then sent him to the University of Edinburgh to complete his medical course. As a senior student he served with the medical corps in the South African War (1899–1902). As a result his father, who was ideologically opposed to the war and upset that Elliott had interrupted his studies, withdrew further financial support. Elliott had to obtain odd jobs and use his savings from military service to complete his medical education. He would later repay his father and the rift was repaired.
Graduating MB, ChB in 1902, Elliott returned to New Zealand the following year and was the first house surgeon at Wellington District Hospital. He then began a surgical and general practice, serving also as honorary surgeon to the hospital. On 12 December 1905, at Wellington, he was married by his father to Annie Allan Forbes from Edinburgh; they were to have five children. In 1912 Elliott took the Edinburgh MD degree. He became a fellow of the American College of Surgeons in 1926 and, the following year, a foundation fellow of the College of Surgeons of Australasia.
An influential member of the New Zealand Branch of the British Medical Association (NZBMA), Elliott was chairman of council for three terms and president in 1929. He was a notable public speaker and a powerful writer with an erudite and flamboyant style, peppered with literary allusions and quotations. His greatest service to medicine was his editorship of the New Zealand Medical Journal from 1911 to 1933. He spoke his mind clearly and did not spare trenchant criticism when he thought the integrity of the medical profession had been impugned. In 1933 he wrote an editorial accusing the executive of the NZBMA of 'mild acquiescence in encroachments on the dignity, rights and liberty of the medical profession'. The executive decided that editorials should reflect official opinion and Elliott resigned. The next editor wrote an appreciation of his services, which Elliott considered 'a poor preliminary epitaph'.
Fluent in Latin and less so in Greek, Elliott wrote Outlines of Greek and Roman medicine in 1914. His autobiography, Scalpel and sword, was published in 1936 and Firth of Wellington, a biography of his old headmaster, in 1937. He also wrote a novel of early New Zealand life, The hundred years, in 1939 and edited and revised H. F. Carleton's life of Henry Williams in 1948. He was a member and president of the New Zealand Centre of PEN.
In the First World War Elliott was medical commander of the hospital ship Maheno and later assistant director of medical services in New Zealand. In the Second World War he was chairman, from 1940 to 1945, of the Joint Council of the Order of St John and the New Zealand Red Cross Society. A leading advocate of cancer research, he organised the New Zealand Branch of the British Empire Cancer Campaign Society (later the New Zealand Cancer Society) and was its president from 1929 to 1955. He was a member of the Medical Council, the Board of Health, the Medical Research Council and the Waitangi National Trust Board.
Elliott was active in the work of the Order of St John from 1906, and served as first chancellor of the Priory in New Zealand from 1946 to 1954. He was promoted to the highest grade in the order, Bailiff Grand Cross, in 1955. During the controversy over the introduction of social security medicine in the 1930s, he was uncompromisingly in favour of preserving medical freedom. He was knighted in 1936, one of the first two knights nominated by the Labour government. In 1939 he received an honorary LLD from the University of Aberdeen.
James Elliott died in Wellington on 26 October 1959. Annie Elliott, MBE and a Dame of Grace of the Order of St John, had died in 1955. Elliott had been an outstanding leader of the medical profession and an outspoken upholder of the ethos of that profession. As his obituary in the New Zealand Medical Journal said: 'His firm belief was in a powerful medical profession with its watchword the unfettered and complete clinical responsibility of the doctor for his patient. In defence of this he laboured mightily'.