-9A B A matter in question. The court exercises a supervisory function over the B legality and constitutionality of administrative decisions. As final relief C C in judicial review proceedings, it may make an order quashing the D E administrative decision in question or declaring it to be vitiated by some error of law or to be unconstitutional. In general, however, the court does D E not tell the administrative body what to do or make the decision for it. F G The court may say a certain policy is unlawful, but the court does not substitute a policy in its place. That would be to usurp the function of the F G body from which the judicial review lies. It is in my opinion crucial to H I J K bear this in mind when considering applications for mandatory orders and, a fortiori, for interim mandatory orders in judicial review proceedings. 21. The same idea is encapsulated in the following passage from the judgment of Laws LJ in R v Ealing LBC ex parte Parkinson (1997) 29 H I J K HLR 179, 185–186: L M N O P Q R S T L “If a defendant’s duty is to exercise discretion and judgment as the delegate of the legislature, the court cannot, generally at least, hold that it should have carried out its task in a particular way — and so deliver a particular result — without usurping the authority which Parliament has conferred by constituting itself a substitute decision-maker on the merits. Even in a case where a decision is struck down in the public law court on Wednesbury grounds, it is by no means a necessary or usual consequence that the public body ought to have acted in one way and one way only. The relief typically given is an order of certiorari to quash the decision, with the result that the respondent must think again. There are, it is true, rare cases where the public law court is able to conclude that only one result was legally open to the body in question, and in that case an order of mandamus may issue to require that result to be arrived at. Even there, however, the court does not undertake the role of primary fact-finder, substituting its judgment on the merits for that of the body reviewed. It merely recognises the existence of a situation in which a public authority, properly directing itself on the facts according to the law, has only one choice legally open to it.” M N O P Q R S T U U V V