Following Labor's victory at the 1972 federal election, Gough Whitlam appointed Murphy as Attorney-General and Minister for Customs and Excise. He oversaw a number of reforms, establishing the Family Court of Australia, the Law Reform Commission, and the Australian Institute of Criminology, and developing the "Family Law Act 1975", which fully established no-fault divorce. He also authorised the 1973 Murphy raids on ASIO. In 1975, following the death of Douglas Menzies, Murphy was appointed to the High Court. He is the most recent politician to be appointed to the court.