(1)The Secretary of State, or a senior official acting on behalf of the Secretary of State, may cancel a bulk acquisition warrant at any time.
(2)If the Secretary of State, or a senior official acting on behalf of the Secretary of State, considers that any of the cancellation conditions are met in relation to a bulk acquisition warrant, the person must cancel the warrant.
(3)The cancellation conditions are—
(a)that the warrant is no longer necessary in the interests of national security,
(b)that the conduct authorised by the warrant is no longer proportionate to what is sought to be achieved by that conduct,
(c)that the examination of communications data obtained under the warrant is no longer necessary for any of the specified operational purposes (see section 161).
(4)But the condition in subsection (3)(a) does not apply where the warrant has been modified so that it no longer authorises or requires the carrying out of activities falling within section 158(6)(a).
(5)Where a warrant is cancelled under this section, the person to whom the warrant was addressed must, so far as is reasonably practicable, secure that anything in the process of being done under the warrant stops as soon as possible.
(6)A warrant that has been cancelled under this section may not be renewed.