The office of Chief Justice is established under section 71 of the Australian Constitution, which establishes the High Court as consisting of a Chief Justice and at least two other Justices.
The Chief Justice is first among equals among the Justices of the High Court, and the position differs little from that of the other members. The one substantial difference between a Chief Justice and any of the other members of the Court is that, by operation of section 23(2) of the Judiciary Act 1903, where opinion on the court is evenly divided, that side of the question supported by the Chief Justice is the side which prevails.
As with all other Justices of Federal courts, appointment is until the mandatory retirement age of seventy. Before 1977, appointment was for life. As the workload of the Court has steadily increased, more Justices have retired before reaching the mandatory retirement age.