18(1)The Secretary of State must issue a code of practice with regard to the exercise of functions under this Schedule.
(2)The code of practice must in particular deal with the following matters—
(a)the procedure for making designations under paragraphs 1(4) and 17;
(b)training to be undertaken by persons who are to exercise powers under this Schedule;
(c)the exercise by constables, immigration officers and customs officials of functions conferred on them by virtue of this Schedule;
(d)information to be given to a person in whose case a power under this Schedule is exercised;
(e)how and when that information is to be given;
(f)reviews under paragraph 6.
(3)A constable, immigration officer or customs official must perform functions conferred on him or her by virtue of this Schedule in accordance with any relevant provision included in the code by virtue of sub-paragraph (2)(c) to (e).
(4)The failure by a constable, immigration officer or customs official to observe any such provision does not of itself make him or her liable to criminal or civil proceedings.
(5)The code of practice—
(a)is admissible in evidence in criminal and civil proceedings;
(b)is to be taken into account by a court or tribunal in any case in which it appears to the court or tribunal to be relevant.