Unlawful Detention in UK Law

In these cases, there is no lawful authority to detain unless a lawful decision is made by the Secretary of State. The mere existence of an internal, unpublished policy or practice at variance with, and more disadvantageous to the FNP than, the published policy will not render a decision to detain unlawful. It must be shown that the unpublished policy was applied to him.

But I do not think that this difference means that Nadarajah offers no assistance in this case. On the contrary, it seems to me to indicate that a failure by the executive to adhere to its published policy without good reason can amount to an abuse of power which renders the detention itself unlawful. I use this expression to describe a breach of public law which bears directly on the discretionary power that the executive is purporting to exercise.

I accept the submission on behalf of the Home Secretary that where there is a risk of absconding and a refusal to accept voluntary repatriation, those are bound to be very important factors, and likely often to be decisive factors, in determining the reasonableness of a person's detention, provided that deportation is the genuine purpose of the detention. The risk of absconding is important because it threatens to defeat the purpose for which the deportation order was made.

Principle (ii) is that the Secretary of State may not lawfully detain a person "pending removal" for longer than a reasonable period. Once a reasonable period has expired, the detained person must be released. Thus, once it becomes apparent that the Secretary of State will not be able to effect the deportation within a reasonable period, the detention becomes unlawful even if the reasonable period has not yet expired.

But in my view they include at least: the length of the period of detention; the nature of the obstacles which stand in the path of the Secretary of State preventing a deportation; the diligence, speed and effectiveness of the steps taken by the Secretary of State to surmount such obstacles; the conditions in which the detained person is being kept; the effect of detention on him and his family; the risk that if he is released from detention he will abscond; and the danger that, if released, he will commit criminal offences.

There can, however, be a realistic prospect of removal without it being possible to specify or predict the date by which, or period within which, removal can reasonably be expected to occur and without any certainty that removal will occur at all. There must be a sufficient prospect of removal to warrant continued detention when account is taken of all other relevant factors.