(1)In deciding whether to approve a decision to issue a warrant under section 138, a Judicial Commissioner must review the Secretary of State’s conclusions as to the following matters—
(a)whether the warrant is necessary as mentioned in subsection (1)(b) of that section,
(b)whether the conduct that would be authorised by the warrant is proportionate to what is sought to be achieved by that conduct,
(c)whether—
(i)each of the specified operational purposes (see section 142) is a purpose for which the examination of intercepted content or secondary data obtained under the warrant is or may be necessary, and
(ii)the examination of intercepted content or secondary data for each such purpose is necessary as mentioned in section 138(1)(d)(ii), and
(d)any matters taken into account in accordance with section 139.
(2)In doing so, the Judicial Commissioner must—
(a)apply the same principles as would be applied by a court on an application for judicial review, and
(b)consider the matters referred to in subsection (1) with a sufficient degree of care as to ensure that the Judicial Commissioner complies with the duties imposed by section 2 (general duties in relation to privacy).
(3)Where a Judicial Commissioner refuses to approve a decision to issue a warrant under section 138, the Judicial Commissioner must give the Secretary of State written reasons for the refusal.
(4)Where a Judicial Commissioner, other than the Investigatory Powers Commissioner, refuses to approve a decision to issue a warrant under section 138, the Secretary of State may ask the Investigatory Powers Commissioner to decide whether to approve the decision to issue the warrant.