28 In my respectful view this passage in Lord Diplock's speech states clearly the basis for the view that the validity of an exercise of statutory power to arrest under subs.352(2) is not established conclusively by showing that the circumstances in subs.352(2)(a) exist, and that the validity of the decision to arrest and the lawfulness of the arrest also depend on the effective exercise of the discretion alluded to by the word "may".
29 Substantially the same view is expressed in the judgment of the Supreme Court of South Australia (Napier CJ, Bright and Mitchell JJ) in Drymalik v. Feldman [1966] SASR 227 at 231 where their Honours said:
In our view, therefore, the appellants, when they arrested the respondent, honestly believed, on reasonable grounds, that he had committed an offence.
However, that is not an end of the matter. The power, which s.75 of the Police Offences Act 1953-1961 entrusts to every member of the Police Force, is admittedly very wide indeed, but that, as it seems to us, imports a power that has to be exercised within the limits, and for the purposes, contemplated by the enactment. It seems to us that it is incumbent on this Court to insist upon this view of the enactment. So that, even if the arrest is effected ostensibly in execution of the statutory power and within its letter, it must nevertheless be held not to come within the power, unless it is effected in good faith, and for the purposes contemplated by the enactment ( Maxwell on the Interpretation of Statutes 9th ed (1946) p.129; Stockton & Darlington Railway Co. v Brown (1860) 9 H.L.C. 246, at p.256 (11 E.R. 724. at p. 728).
…
We think therefore that the appellants were rightly adjudged guilty of the tort of false imprisonment, but we cannot, with all respect, accept the basis upon which that finding has proceeded. We think that the appellants had reasonable grounds for suspecting that the plaintiff had committed the offence for which the appellants purported to arrest him, and, if he had been taken before the justice without unnecessary delay, the plaintiff would have had no ground of complaint. But if the purpose of the arrest was to afford an opportunity for questioning, then the arrest was unlawful, and, be that how it may, the detention whilst the plaintiff was being questioned was unlawful.
30 Lord Diplock eschewed repetition of the Wednesbury principles. Associated Provincial Picture Houses Ltd v. Wednesbury Corporation [1948] 1 KB 223 contains a classic exposition of principles which has been applied many times in England and in Australia when examining validity of exercise of statutory and common law powers of many different kinds. It seems useful to refer to the judgment of Lord Greene MR in Wednesbury at 228-229 on the power of the Courts to review an exercise of discretion by an executive authority. His Lordship said:
When an executive's discretion is entrusted by Parliament to a body such as the local authority in this case, what appears to be an exercise of that discretion can only be challenged in the courts in a strictly limited class of case. As I have said, it must always be remembered that the court is not a court of appeal. When discretion of this kind is granted the law recognises certain principles upon which that discretion must be exercised, but within the four corners of those principles the discretion, in my opinion, is an absolute one and cannot be questioned in any court of law. What then are those principles? They are well understood. They are principles which the court looks to in considering any question of discretion of this kind. The exercise of such a discretion must be a real exercise of the discretion. If, in the statute conferring the discretion, there is to be found expressly or by implication matters which the authority exercising the discretion ought to have regard to, then in exercising the discretion it must have regard to those matters. Conversely, if the nature of the subject-matter and the general interpretation of the Act make it clear that certain matters would not be germane to the matter in question, the authority must disregard those irrelevant collateral maters. There have been in the cases expressions used relating to the sort of things that authorities must not do, not merely in cases under the Cinematograph Act but, generally speaking, under other cases where the powers of local authorities came to be considered. I am not sure myself whether the permissible grounds of attack cannot be defined under a single head. It has been perhaps a little but confusing to find a series of grounds set out. Bad faith, dishonesty-those of course, stand by themselves- unreasonableness, attention given to extraneous circumstances, disregard of public policy and things like that have all been referred to, according to the facts of individual cases, as being matters which are relevant to the question. If they cannot all be confined under one head, they at any rate, I think, overlap to a very great extent. For instance, we have heard in this case a great deal about the meaning of the word "unreasonable."
It is true the discretion must be exercised reasonably. Now what does that mean? Lawyers familiar with the phraseology commonly used in relation to exercise of statutory discretions often use the work "unreasonable" in a rather comprehensive sense. It has frequently been used and is frequently used as a general description of the things that must not be done. For instance, a person entrusted with a discretion must, so to speak, direct himself properly in law. He must call his own attention to the matters which he is bound to consider. He must exclude from his consideration matters which are irrelevant to what he has to consider. If he does not obey those rules, he may truly be said, and often is said, to be acting "unreasonably." Similarly, there may be something so absurd that no sensible person could ever dream that it lay within the powers of the authority. Warrington L.J. in Short v. Poole Corporation [1926] Ch.66, 90, 91 gave the example of the red-hared teacher, dismissed because she had red hair. That is unreasonable in one sense. In another sense it is taking into consideration extraneous matters. It is so unreasonable that it might almost be described as being done in bad faith; and, in fact, all these things run into one another.
31 When Lord Diplock went on in Holgate-Mohammed v. Duke to apply the Wednesbury principles his Lordship reached a conclusion which, it is altogether clear, would not be reached in Australian law because his Lordship treated the following as relevant to the exercise of the discretion:
Detective Constable Offin thought that she would be more likely to confess to what he had reasonable cause to believe to be the truth, if she were arrested and taken for questioning to the police station. In other words, the reason why Detective Constable Offin arrested her was that he held the honest opinion that the police inquiries were more likely to be fruitful in clearing up the case if Mrs. Holgate-Mohammed were compelled to go to the police station to be questioned there…
32 In Australian law such conclusion is clearly not a relevant basis, but is a vitiating basis on which to decide to effect an arrest. There is marked divergence between the law as understood in England, commencing with Dallison v. Caffery [1965] 1 QB 348 in which Lord Diplock as Diplock LJ was a member of the Court of Appeal, and the law in Australia, distinctly stated in Williams v. The Queen and appearing also in many other places. Mason and Brennan JJ in Williams v. The Queen reviewed and stated the Australian law at 292-299, referring to the authorities theretofore, the leading authorities being Bales v. Parmeter (1935) 35 SR (NSW) 182 at 188-190 (Jordan CJ) and R v. Banner [1970] VR 240 at 249-250. There are statements in Bales v. Parmeter at 188 to the effect that an arrest merely for the purpose of asking questions is not lawful; and in Ex parte Evers Re Leary (1945) 62 WN (NSW) 146 at 147 (Maxwell J) to the effect that because the arrest was for the purpose only of questioning it was at all times illegal.
33 The passages from the judgment of Jordan CJ in Bales v. Parmeter show that a purported exercise of the power of arrest for a purpose extraneous to the purpose of taking the person arrested before a magistrate is not authorised by law. At 188, his Honour said:
Where the imposition of physical restraint is authorised by law it may be imposed only for the purpose for which it is authorised.