The first principle of Australian administrative law is that judicial review of administrative action is limited to the legality of decisions, not the merits.
Parliament marks out the metes and bounds of the decision-maker’s power, and within those boundaries, the decision-maker is free to reason and determine matters as he or she likes.
As His Honour Justice Brennan put it in Attorney-General v Quin:
“The duty and jurisdiction of the court to review administrative action does not go beyond the declaration and enforcing of the law which determines the limits and governs the exercise of the repository’s power. If, in so doing, the court avoids administrative injustice or error, so be it; but the court has no jurisdiction simply to cure administrative injustice or error. The merits of administrative action, to the extent that they can be distinguished from legality, are for the repository of the relevant power and, subject to political control, for the repository alone.”
In other words, the role of the court is simply to ensure that the decision-maker acts within the power given to the decision-maker by parliament. It is not the role of the court to substitute its own view about the correct or preferable decision.
His Honour even went on in Quin to suggest that if the court were to engage in merits review it would put its own legitimacy in risk, and several judges have said it would alter the balance between the legislature and the judiciary, and thus undermine the balance of power between them.
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