Are grounds of judicial review so poorly defined that they enable the courts to pick and choose the cases in which they will grant judicial review? Should that be the case?
Substantive Grounds of Review: Unreasonableness
Unreasonableness as a ground of review is difficult to define with any clarity or certainty and as a direst result has often been branded as a problem ridden aspect of administrative law. The concept of Wednesday unreasonableness, formulated in the case of Associated Provincial Picture Houses v. Wednesbury Corporation  and further developed in Council of Civil Service Unions v. Minister for the Civil Service  per Lord Diplock was that courts would intervene to correct an administrative action based on the ground of reasonableness only if it was "so outrageous in its defiance of logic or accepted moral standards that no sensible person who had applied his mind to the question to be decided could have arrived at it."
Indeterminacy as to the definition of Unreasonableness: Poorly defined grounds of review?
The concept of unreasonableness as propagated by Lord Greene and adopted by Australian courts is inherently indeterminate. Whether a particular decision is reasonable or not is often nothing more than a question of degree and opinion by the courts. This creates an overt sense of arbitrariness which then calls into question the consistency and subsequently effectiveness of such a ground of review as illustrated by case law.
The effectiveness of unreasonableness as a ground of review was blatantly called into question in the case of Chan v Minister for Immigration and Ethnic Affairs where the High Court and the Federal Court differed in opinion as to what constituted unreasonableness which was manifestly unfair. This apparent inability of the courts to reach a consensus on what precisely constitutes the required degree of unreasonableness in order to allow a reversal of the disputed administrative decision calls into question the consistency with which it can be applied by courts.
Although subsequent cases (Prasad v Minister for Immigration and Ethnic Affairs/ Luu v Renevier/ Minister for Aboriginal Affairs v Peko-Wallsend) seemed to prefer an expansive interpretation of unreasonableness, in neither of these cases can it be said that the delegate’s decision represented something that was manifestly unfair or overwhelming as required by Lord Greene’s original version. Conversely, it can be argued that the Federal Court simply reviewed the merits of the case and substituted its decision for that of the original one. In these cases although it was difficult to reach the conclusion that the decision was so unreasonable that no reasonable person would have come to them, that is exactly what the courts did. This further prompts arguments that the ground of unreasonableness is so poorly defined that courts can pick and choose the cases in which they grant judicial review.
The wider the interpretation of unreasonableness greater the risk that courts are in essence given greater opportunity to conduct a merits based review with the effect being that judicial review becomes less effective as it loses the element of consistency. In light of this realization, this ground has recently come under close scrutiny by both the judiciary and the legislature. Where unreasonableness does exist as a ground of review, both the High Court and the Federal Court have held unequivocally that it must be strictly construed and that the courts must abstain from using unreasonableness as a guise to hear an appeal and so engage in merits review of a case. In the cases of Minister of immigration and Ethnic Affairs v Eshetu and Minister for Immigration and Multicultural Affairs v Betkhoshabeh, the Court established strict constraints for unreasonableness, insisting that it is only to be used in the most extreme of cases and that the review should only extend to...