On 14 June 1938, Bourne was arrested after performing an operation without fee at St Mary's Hospital to terminate the pregnancy of six weeks of a 14-year-old girl who had been sexually assaulted by five off-duty British soldiers, officers in the Royal Horse Guards, in a London barracks.
His defence had been based on the Infant Life (Preservation) Act 1929 in which, under British law, the only recognised justification for the termination of a pregnancy was if the life of the woman was in danger.