103. As a principle, it seems to me to be self-evident that, if a public body is under an obligation to provide accommodation and other services to meet a statutory requirement, the public body must ascertain the requirement it is obliged to meet, before deciding how it should be met.

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105. Section 3(1) is a general duty (see paragraph 17 above); and, as the authorities emphasise, the ‘obligation is limited to providing the services identified to the extent that [the relevant authority] considers that they are necessary to meet all reasonable requirements’ (Coughlan at [23] per Lord Woolf MR, in relation to the similarly worded provision in the 1977 Act: emphasis in the original). This necessarily places considerable discretion – or judgment as, in this context, it is perhaps better described – in the hands of the authority.

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107. However, the exercise of judgment is not restricted to the substantive scope of the reasonable requirements, and the services the relevant authority considers necessary to meet those requirements. The authority also has a substantial degree of flexibility as to how it goes about its task. That principle is derived from cases such as CREEDNZ Inc v Governor General of New Zealand [1981] 1 NZLR 172 and In re Findlay [1985] AC 318, and described by Laws LJ in R (Khatun) v London Borough of Newham [2004] EWCA Civ 55; [2005] QB 37 at [35].

108. The principle bears upon this case in two ways.

109. First, before making an assessment of reasonable requirements or necessary services to meet them, the authority must consider whether the information it has is sufficient for it to make a properly informed decision; but that in itself requires an exercise of judgment with which this court will only interfere on public law grounds.

110. Second, Mr Wise submits that the various authorities here – notably the UHB and the WHSS Committee – erred in not focusing upon a category of patient which he has defined for the purpose and into which the Claimant falls, namely women with ASD and LD who require or may require in-patient mental healthcare (see, eg paragraph 1 of his skeleton argument). They erred, he says, in not collecting information and data about that group, and in not making a distinct discrete decision with regard to commissioning and financing (or not) of further secure accommodation in Wales for that group.

111. However, that, in my respectful view, is a somewhat simplistic view of the relevant decision-making, which misunderstands the nature of the relevant decisions. Mr Wise criticises the UHB and the WHSS Committee for not collating data in respect of a group he defines – ie women who require secure accommodation because of behaviour stemming from ASD and LD – and, thereafter, for not considering and making decisions concerning the requirements of the individuals in that group. But:

i) It is for the relevant authorities (the LHBs and the WHSS Committee in this case) to consider the criteria for the scope relevant clinical areas in respect of which, in their considered view, planning can best be made. The authorities have a wide margin of discretion in respect of the criteria they chose, and how they apply them. This assessment too requires judgment with which, for the reasons I have given, the courts will not lightly interfere.ii) It is in any event, in my view, arguably artificial to create a cohort by reference to the primary criterion lit upon by Mr Wise, i.e. a diagnosis of both ASD and LD, coupled with or uncoupled from the secondary criterion of a potential need for secure placement. A cohort is a group of people with a characteristic in common; and, in this context, that characteristic must be such that the individuals in the cohort have at least some common ‘reasonable requirements’. However, as Mr Williams submitted, individuals with complex diagnoses including (but often, as in the Claimant’s case, not restricted to) ASD and LD have varying degrees of mental health and often physical health disabilities, with different consequential behaviours and care and treatment needs, which (as again the Claimant illustrates) themselves can vary greatly over time. This is particularly so with behavioural conditions such as LD which, as I understand it, are not curable, treatment going to the goal of enabling individuals to cope with the disability. That inevitably requires a particularly subjective approach. As the Claimant’s mother emphasises in her statement of 2 November 2015, such patients may at times need particularly specialised assessment, treatment and care, tailored to his or her particular condition and behaviour. Even if patients need secure provision, the nature of the required facilities will vary. Such individuals are clinically idiosyncratic, and may not have any or sufficient commonality in their ‘reasonable requirements’ to classify as a ‘cohort’ (see, eg, paragraphs 11–12 of Mr Andrew’s statement dated 16 September 2015). That is particularly so if, as here, they are small in number.iii) However, even if they can be properly categorised as Mr Wise suggests, the decision to be made about their reasonable requirements and how they might be met does not concern simply them. Such decisions cannot be made in a vacuum, or (as Mr Williams put it) in isolation from the competing needs and priorities of other cohorts of patients. To consider reasonableness of their requirements means assessing them in the context of the needs of a multiplicity of other patients and potential patients, and the many other calls on public resources allocated to NHS Wales. It is unrealistic to impose upon the relevant authority an obligation discretely to consider every possible group and subgroup of patients and potential patient, no matter how narrowly defined, who may wish to use the services of NHS Wales; and to make a discrete decision as what their precise requirements will be and whether to prioritise their needs or otherwise favour them over others with different health requirements. The relevant decision-making process is therefore particularly sophisticated. It can sensibly be done – and, perhaps, only sensibly done – in the context of a scheme whereby the requirements of all patients and potential patients are taken into account somewhere along the line.iv) NHS Wales has such a scheme. It is described in paragraphs 59–60 above. The scheme, on a bottom up basis, is designed to identify and consider the requirements of all patients and potential patients; and the prioritisation of those requirements for the purposes of planning, including planning capital and other public expenditure. That scheme is not challenged in these proceedings.