Commentary on provisions of the Act Section 12: Period for which persons may be detained
This section replaces, in part, the common law Hardial Singh principles with a codified statutory version of the second and third principles. The four Hardial Singh principles, which apply with necessary modification to all immigration detention powers, are as follows:
	the Secretary of State must intend to deport the person and can only use the power to detain for that purpose;
the deportee may only be detained for a period that is reasonable in all the circumstances;
if, before the expiry of the reasonable period, it becomes apparent that the Secretary of State will not be able to effect deportation within a reasonable period, they should not seek to exercise the power of detention;
the Secretary of State should act with reasonable diligence and expedition to effect removal.
	As well as codifying, in part, the Hardial Singh principles, this section also overturns the common law principle established in R(A) v SSHD [2007] EWCA Civ 804 (and later authorities) that it is for the court to decide, for itself, whether there is a reasonable or sufficient prospect of removal within a reasonable period of time.
	Subsection (1)(a) inserts new sub-paragraph (5) in paragraph 16 of Schedule 2 to the 1971 Act, which confers a power to detain persons liable to examination or removal, the purpose of which is to signpost the provisions in new paragraph 17A.
	Subsection (1)(b) inserts new paragraph 17A(1) to (7) into Schedule 2 to the 1971 Act. It provides that a person liable to detention under paragraph 16 may be detained for such period as, in the opinion of the Secretary of State, is reasonably necessary to enable the examination, decision, removal or directions to be carried out, made or given. The powers to detain under paragraph 16 apply irrespective of any impediment to those statutory purposes for the time being. The effect of this section is to clarify that it is for the Secretary of State, rather than the courts, to determine what is a reasonable period to detain an individual for the specific statutory purposes (for example, to effect removal from the UK), subject to any statutory limitations on the period of detention where relevant. If the Secretary of State does not consider that the examination, decision, removal or directions will be carried out, made or given within a reasonable period of time, the person may be detained for a further period that is, in the opinion of the Secretary of State, reasonably necessary to enable arrangements to be made for release that the Secretary of State considers to be appropriate. This section also covers the detention of those who are to be removed from or on a ship or aircraft.
	Subsections (2) to (6) amend paragraph 2 of Schedule 3 to the 1971 Act, (detention pending deportation), section 10(9) of the 1999 Act (detention of persons unlawfully in the UK), section 62 of the 2002 Act (detention by Secretary of State), section 36 of the 2007 Act (detention relating to deportation) and regulation 32 of the Immigration (European Economic Area) Regulations 2016 respectively, so that the codification of the second and third Hardial Singh principles, as described in paragraph 101 above, applies to the detention powers provided for in those provisions.