Schedule 3, Part 3 Review of detention (paras. 52-55)
General requirements
(1) The detention of a person ("the detainee") under Part 1 of this Schedule must be periodically reviewed by a review officer.
(2) The first review must be carried out before the end of the period of one hour beginning with the detainee's detention under that Part.
(3) Subsequent reviews must be carried out at intervals of not more than two hours.
(4) The review officer may authorise a detainee's continued detention under Part 1 of this Schedule only if satisfied that it is necessary for the purposes of exercising a power under paragraph 1 or 2.
(5) If on a review under this paragraph the review officer does not authorise a detainee's continued detention, the detainee must be released (unless detained under another power).
(6) In this Part of this Schedule "review officer" means a senior officer who has not been directly involved in questioning the detainee under paragraph 1 or 2.
(7) "Senior officer" means -