The issue surrounds "out-of-country" appeals. These are appeals against immigration decisions made by the Home Secretary which immigrants are entitled to bring before the First-tier Tribunal (Immigration and Asylum Chamber) ("the tribunal") but only if they bring them when they are outside the UK.
Mr Kiarie, the first appellant, has Kenyan nationality. He is aged 23 and has lived in the UK with his parents and siblings since 1997, when he was aged three. In 2004 he was granted indefinite leave to remain in the UK. He has been convicted of serious offences in relation to drugs. Sent to him under cover of a notice dated 10 October 2014 was an order made by the Home Secretary for his deportation to Kenya.
Mr Byndloss, the second appellant, has Jamaican nationality. He is aged 36 and has lived in the UK since the age of 21. In 2006 he was granted indefinite leave to remain in the UK. He has a wife and their four children living here; and he has three or four other children also living here. He has been convicted of a serious offence in relation to drugs. Sent to him under cover of a notice dated 6 October 2014 was an order made by the Home Secretary for his deportation to Jamaica.
In deciding to make deportation orders against them, the Home Secretary rejected the claims of Mr Kiarie and Mr Byndloss that deportation would breach their right to respect for their private and family life under article 8 of the European Convention on Human Rights ("the Convention"). Mr Kiarie and Mr Byndloss have a right of appeal to the tribunal against her rejection of their claims and they propose to exercise it. But, when making the deportation orders, the Home Secretary issued certificates, the effect of which is that they can bring their appeals only after they have returned to Kenya and Jamaica.
As I will explain in paras 33 and 55, it may well, for obvious reasons, be difficult for Mr Kiarie and Mr Byndloss to achieve success in their proposed appeals. But the question in these proceedings is not whether their appeals should succeed. It is: are the two certificates lawful?
Yes, said the Court of Appeal (Richards LJ, who gave the substantive judgment, and Elias and McCombe LJJ, who agreed with it) on 13 October 2015,  EWCA Civ 1020,  1 WLR 1961, when dismissing the applications of Mr Kiarie and Mr Byndloss for judicial review of the certificates.
A requirement that some appeals against immigration decisions be brought "out-of-country" has been a feature of the legal system referable to immigration ever since the Immigration Act 1971 ("the 1971 Act") came into force. An obvious example is when people abroad apply unsuccessfully to entry clearance officers in British embassies and High Commissions for entry clearance, ie permission to be admitted to the UK. They often have a right of appeal to the tribunal against the refusal of entry clearance and they are required to bring their appeals from abroad. But such appellants are already abroad; indeed their appeals are often in a narrow compass which surrounds their ability to satisfy the evidential (in particular the documentary) requirements of the Immigration Rules; their appeals do not usually include human rights claims and it is the oral evidence of their sponsors in the UK, rather than of themselves, which is often the more important. The situation is different when the proposed appeal is based on human rights and when the requirement to bring it from abroad is imposed on an appellant who is in the UK and who must therefore leave before he can bring it.
not having been begun or not having been exhausted, removal of P to the country or territory to which P is proposed to be removed, pending the outcome of an appeal in relation to P's claim, would not be unlawful under section 6 of the Human Rights Act 1998 (public authority not to act contrary to Human Rights Convention).
(3) The grounds upon which the Secretary of State may certify a claim under subsection (2) include (in particular) that P would not, before the appeals process is exhausted, face a real risk of serious irreversible harm if removed to the country or territory to which P is proposed to be removed."
With effect from 1 December 2016, section 94B of the 2002 Act (to which I will refer simply as section 94B) has been amended by section 63 of the Immigration Act 2016 so as to extend the Home Secretary's power to certify under the section. Since then she has had power to certify any human rights claim irrespective of whether the claimant is liable to deportation. The extended power does not fall to be considered in these appeals but our decision today will surely impact on the extent of its lawful exercise.
Section 3(5)(a) of the 1971 Act provides that a person who is not a British citizen is liable to deportation from the UK if the Home Secretary deems his deportation to be conducive to the public good.
Section 32(4) of the UK Borders Act 2007 ("the 2007 Act") provides that, for the purpose of section 3(5)(a) of the 1971 Act, the deportation of a "foreign criminal" is conducive to the public good. Section 32(1) and (2) defines a "foreign criminal" as a person who is not a British citizen and who is convicted in the UK of an offence for which he is sentenced to a period of imprisonment of at least 12 months. My future references to a foreign criminal will be to a person as thus defined.
Section 32(5) of the 2007 Act provides that, unless an exception specified in section 33 applies and therefore, in particular, unless his removal would breach his rights under the Convention, the Home Secretary must make a deportation order in respect of a foreign criminal.
At the material times, section 82(1) and (3A) of the 2002 Act provided that, where a deportation order in respect of a person was stated to have been made in accordance with section 32(5) of the 2007 Act, he might appeal to the tribunal. By section 82(4), however, the right of appeal was subject to limitations.
One limitation, relevant to the present appeals, arose in the conjunction of section 92(1) and (4)(a) of the 2002 Act with section 94(1) and (2) of it. Section 92(1) provided that an appeal under section 82 could not be brought while the appellant was in the UK unless it fell within one of the exceptions specified in later subsections. Subsection (4)(a) specified one exception, namely where the appellant had made a human rights claim while in the UK. Section 94(1) and (2), however, provided that an appellant could not rely on section 92(4)(a), ie in order to be entitled to bring his appeal from within the UK, if the Home Secretary certified that his human rights claim was "clearly unfounded".
But another limitation is of even greater relevance to the present appeals. This was the provision which accompanied the coming into force of section 94B on 28 July 2014. The provision was that, where under that section the Home Secretary certified a human rights claim made by a person liable to deportation, his appeal could be brought only from outside the UK. In relation to the deportation orders made in relation to Mr Kiarie on 10 October 2014 and to Mr Byndloss on 6 October 2014, such was the effect of article 4 of the Immigration Act 2014 (Commencement No 1, Transitory and Saving Provisions) Order 2014 (SI 2014/1820), continued by article 15 of a third commencement order (SI 2014/2771). In relation to deportation orders made on or after 20 October 2014, such was the effect of section 92(3)(a) of the 2002 Act.
There is no right of appeal to the tribunal against a certification under section 94B. As these proceedings show, the challenge is by way of judicial review.