Since the late 1990s it has become increasingly clear that the Commonwealth Constitution is the dominant influence upon judicial review of administrative action in Australia. The Constitution provides for a minimum entrenched provision of judicial review by recognising and protecting the supervisory jurisdiction of the High Court. This protection comes at a price because the separation of powers doctrine and the division and allocation of functions it fosters impose many limits upon the reach and content of judicial review of administrative action. This protective and restrictive effect of the separation of powers upon judicial review of administrative action arguably reflects a wider tension in the separation of powers, in which the powers and limits of each arm of government are balanced in a wider sense.