The result of appeal will have satisfied neither side; both sides losing their appeal and cross-appeal respectively and most importantly for Mr Rahmatullah there is no remedy against his current unlawful detention. He remains detained without any immediate prospect of release despite the issue of a writ of habeas corpus ad subjiciendum in his favour. The case does, however, represent a significant and interesting decision in respect of the law of habeas corpus in a cross-border setting, and in its analysis of whether the Courts may stray into an area contended by the Secretaries of State to be the preserve of diplomatic relations.

Judgment in was handed down on Wednesday by a seven strong bench; the majority (Lords Phillips, Kerr, Dyson, Wilson and Reed) refusing the Secretaries of State’s appeal and the appellant’s cross-appeal and a minority (Lady Hale and Lord Carnworth) dissenting from the majority on the cross-appeal.

The appeal concerned a habeas corpus application made on behalf of Mr Rahmatullah, a Pakistani citizen, who was taken into custody by British forces in Iraq in 2004 and then transferred to US Forces in accordance with the terms of a Memorandum of Understanding. The appellant was subsequently transferred by US Forces out of Iraq to a detention facility in Bagram Air Field in Afghanistan, where he remains to this day.

The majority of habeas corpus cases have concerned individuals who were held in the jurisdiction and where there was no question of control. Prior to this judgment there was only two cases (Barnado v Ford [1892] AC 326 and ex p O’Brien [1923] 2 KB 361) in which the English court had issued the writ where the defendant had unlawfully removed the prisoner from the jurisdiction and where it was uncertain whether the defendant retained sufficient control over the prisoner to procure his release. The purpose of the issue of the writ in those cases was to test the question of control. The appellant in this case sought to uphold the decision of the Court of Appeal to issue the writ and further the impose on the Secretaries of State the obligation to take further steps to persuade the United States to release him. The Secretaries of State submitted that there was no prospect of the US acceding to any request for release and therefore that the issuing of a writ in these circumstances was not appropriate. They further argued that the issue of whether to request the US to release the appellant was a matter which fell within the conduct of the foreign affairs of the UK such that the Courts should not interfere (the so-called forbidden territory argument).

The present appeal marks a step further along the route of issuing writs. Both the earlier cases involved an unlawful detention that had taken place within the jurisdiction followed by an unlawful transfer out. In Rahmatullah there was no suggestion that the UK had acted unlawfully in detaining the appellant in Iraq, nor in transferring him to the custody of the US. The criticism levied at the UK was in its failing to observe its obligations under one or other Geneva Conventions.  As such it will likely have important implications for other detainees who have been arrested by British forces and then handed over to a foreign state whether under a Memorandum of Understanding or otherwise. It will affect the UK’s treatment of detainees in present and future conflicts. It also is significant in that it overrides the Secretaries of State’s arguments about non-interference in an area involving foreign affairs.

The leading judgment in the appeal was given by Lord Kerr (with whom Lords Dyson and Wilson agreed) who analysed in some detail the existing authorities and held that it was proper to apply the O’Brien approach to resolve the uncertainty as to whether the US would respond to a request to release the appellant. He found it significant in the case that there was clear prima facie evidence that Mr Rahmatullah was unlawfully detained (para. 53) in that his detention was in violation of the Geneva Convention Relative to the Protection of Civilian Persons in Time of War. He also considered it important that the Court of Appeal had unequivocally found that there was sufficient reason to conclude that the Secretaries of State would be able to assert control over the custody of the appellant (para. 54). He held that this did not tread on the forbidden territory and rejected the argument that the writ in this case required the Secretaries of State to engage at a diplomatic level with the US. He dealt with the argument of interference in diplomacy by stating that the Court of Appeal’s judgment in fact did not require the Secretaries of State to act in any particular way in order to demonstrate whether they could or could not exert control. What was required of them was to show by whatever means they could, whether or not control existed. It did not require the UK government to engage in a process of persuasion or make any particular diplomatic move (paras. 63, 70).

On the cross-appeal Lord Kerr held that on the evidence that the letter from US unequivocally asserted that the US was legally entitled to hold Mr Rahmatullah. On this area he allowed the Secretaries of State rather more scope in terms of not second-guessing diplomatic correspondence.

The debate as to the extent the writ of habeas corpus may be used in a ‘foreign’ case is by far from exhausted. Both the judgments of Lord Phillips and Lord Reed, which additionally succinctly analyse the main points in contention, make clear that they consider a number of interesting and difficult legal issues to be as yet undecided: see paras. 106 and 115. In particular they raised the question of the interface between habeas corpus, judicial review and the doctrine of legitimate expectation.

There is a powerful dissent on the question of the cross-appeal in this case. Lady Hale and Lord Carnworth questioned why the US government should have had any diplomatic problem in expressing its position clearly as to whether the UK retains an interest as detaining authority and under the Memorandum of Understanding. In the sphere of liberty of the subject they noted that it was not the Court’s job to speculate as to the political sensitivities which may be in play (para. 129). Their reasoning is compelling and indeed given the unfortunate position of the appellant might have provided at least some form of clarification as to his status in US detention.