“In Lumba’s case Lord Dyson stated (at [22]) that the Hardial Singh principles reflect the basic public law duties to act consistently with the statutory purpose and reasonably in the Wednesbury sense. But he also stated (at [30]) that they are not exhaustive, and do not therefore preclude the operation of the public law duty of adherence to published policy. Chapter 55.1.1 of the policy is to the same effect. It states that “(t)o be lawful detention must not only be based on one of the statutory powers and accord with the limitations implied by domestic and Strasbourg case law but must also accord with stated policy.”
“55.10 Persons considered unsuitable for detention The following are normally considered suitable for detention in only very exceptional circumstances… … • Those suffering from serious medical conditions which cannot be satisfactorily managed within detention (and) • Those suffering serious mental illness which cannot be satisfactorily managed within detention…”
“37. As the judge held, Chapter 55.10 is clearly directed to the normal circumstances in which the policy is required, ie detention in removal centres and prisons. When read in this way the consequence of the applicability of the policy is not that those to whom it applies become unsuitable for detention anywhere simply because their conditions are unsuitable for treatment in a removal centre or prison. Its effect is not that, in the absence of very exceptional circumstances, continued detention is unsuitable but that the detention in the removal centre or prison is unsuitable. As both Ouseley J and Stewart J observed, the result is not that a detainee must be released unless there are very unusual circumstances but that the detainee must be moved to a suitable place of detention. A person may be fit to be detained in a hospital even if not fit to be detained in an IRC. 38 ……The failure of the policy to make express provision for those who require removal to hospital but who otherwise remain in detention is, as the judge observed, because it was so obvious as to be not worth saying that those who needed medical treatment not available in an IRC or prison would pursuant to the proper application of the policy be transferred to hospital in detention. Furthermore, any failure to state in a published policy that those not suitable for detention in an IRC should be removed in detention to hospital where their medical needs could more suitably be met does not limit the exercise of the power conferred on the respondent. She does not need to announce a policy covering a particular situation or to act in accordance with it in order to make the exercise of her powers lawful.”