The decision of the Supreme Court in R (Lumba) v Secretary of State for the Home Department  UKSC 12,  2 WLR 671 is important both for what it says about the rule of law (see ch 2 of the book) and for what it says about unpublished Government guidelines or policies (see ch 7 of the book). The case was formerly known as WL (Congo) v Secretary of State for the Home Department.
The case is one of a number that arises out of a political storm in 2006, when it became public that more than 1000 foreign national prisoners in the UK had been released rather than considered for deportation. The media storm was such that the incumbent Home Secretary (Charles Clarke) was replaced, John Reid becoming the new Secretary of State.
Home Office policy had been to presume that foreign national prisoners should be released upon completion of their sentence, rather than re-detained with a view to deportation, although the latter course would be adopted in some circumstances. John Reid abandoned this policy and replaced it with a new one: namely, that there would be a “near blanket ban” on releasing foreign national prisoners. This policy remained unpublished — that is, secret — from its adoption in April 2006 until September 2008.
Mr Lumba was one of numerous foreign national prisoners who were caught by the Home Office’s unpublished change of policy. Instead of being released from prison on the completion of his sentence, he was detained pending deportation. On his behalf, it was argued that his detention was unlawful (and was therefore false imprisonment) on the basis, among other matters, that his detention was on the basis of a secret policy which, moreover, was in direct conflict with the published policy of HM Government. Argument in the case was heard over four days in front of a panel of nine Supreme Court Justices who ruled six-to-three in Lumba’s favour. The lead judgment for the majority was delivered by Lord Dyson.
Lord Dyson stated as follows:
The rule of law calls for a transparent statement by the executive of the circumstances in which the broad statutory criteria will be exercised. Just as arrest and surveillance powers need to be transparently identified through codes of practice and immigration powers need to be transparently identified through the immigration rules, so too the immigration detention powers need to be transparently identified through formulated policy statements.
The individual has a basic public law right to have his or her case considered under whatever policy the executive sees fit to adopt provided that the adopted policy is a lawful exercise of the discretion conferred by the statute: see In re Findlay  AC 318, 338E. There is a correlative right to know what that currently existing policy is, so that the individual can make relevant representations in relation to it …
The precise extent of how much detail of a policy is required to be disclosed was the subject of some debate before us. It is not practicable to attempt an exhaustive definition. It is common ground that there is no obligation to publish drafts when a policy is evolving and that there might be compelling reasons not to publish some policies, for example, where national security issues are in play. Nor is it necessary to publish details which are irrelevant to the substance of decisions made pursuant to the policy. What must, however, be published is that which a person who is affected by the operation of the policy needs to know in order to make informed and meaningful representations to the decision-maker before a decision is made.
The Court ruled that, because the policy was unpublished it was unlawful. And the Court further ruled that, because Lumba had been detained under an unlawful policy, his detention was unlawful. His claim for false imprisonment was therefore made out. The Secretary of State had argued that Lumda would have been detained pending deportation even if the published policy had been applied to him. The majority of the Supreme Court ruled that this was irrelevant. On this matter, Lord Dyson stated as follows:
All that a claimant has to prove in order to establish false imprisonment is that he was directly and intentionally imprisoned by the defendant, whereupon the burden shifts to the defendant to show that there was lawful justification for doing so … All that the claimant has to do is to prove that he was detained. The Secretary of State must prove that the detention was justified in law. She cannot do this by showing that, although the decision to detain was tainted by public law error …, a decision to detain free from error could and would have been made.
The fact that, had the Secretary of State applied the published policy, there was no doubt that Mr Lumba would in any event have been detained pending deportation upon the completion of his prison sentence, the Court ruled that he was entitled to nominal damages only, and not to exemplary damages.
Lord Hope, Lord Walker, Lady Hale, Lord Collins and Lord Kerr accompanied Lord Dyson in the majority; Lords Phillips, Rodger and Brown dissented. A follow-up decision is R (Kambadzi) v Secretary of State for the Home Department  UKSC 23,  1 WLR 1299 (formerly known as SK (Zimbabwe) v Secretary of State for the Home Department).