s 18 Investigation in arrestable cases
18.—(1) A police officer may exercise all or any of the special powers of investigation under sections 21, 22, 34, 39 and 111 when investigating any arrestable case.(2) The action of a police officer in such a case may not be called into question at any time on the ground that he or she lacked authority under this section to exercise the special powers of investigation under sections 21, 22, 34, 39 and 111. —(1) A police officer may exercise all or any of the special powers of investigation under sections 21, 22, 34, 39 and 111 when investigating any arrestable case. (2) The action of a police officer in such a case may not be called into question at any time on the ground that he or she lacked authority under this section to exercise the special powers of investigation under sections 21, 22, 34, 39 and 111.