'Referendums are both ordinary and extraordinary. Ordinary because all constitutions have a method to allow for the future alteration of the text, recognising that societies are not static and change over time. But referendums can also be extraordinary because they can lead to transformative, once-in-a-blue-moon change. In constitutional law we sometimes call this “a constitutional moment”. The last successful change to the Australian Constitution, in 1977 – introducing a retirement age for judges in federal courts – was practical. Uninspiring? Yes. Sensible? Also yes. A constitutional moment? No. Yet in the dying days of the Trump presidency, when Americans debated a mandated retirement age for Supreme Court justices, and the reality of brazenly ideological, judicial appointments-for-life dawned upon many, we were reminded of our sage pragmatism 43 years ago.' (Introduction)