Part 6: Bulk warrants Chapter 2: Bulk acquisition warrants Section 164: Modification of warrants
This section sets out the modifications that may be made to a bulk acquisition warrant.
	The only modifications that may be made are adding, varying or removing any operational purpose specified in the warrant or providing that the warrant no longer provides for the acquisition of data covered by the warrant.
	Subsections (4) and (5) require that any modification to add or vary an operational purpose (a major modification) must be made by the Secretary of State and, except in urgent cases, approved by a Judicial Commissioner.
	Subsection (6) provides that a senior official, acting on behalf of the Secretary of State, may make a modification to remove an operational purpose or to cancel the collection of data (a minor modification). Where a minor modification is made by a senior official, the Secretary of State must be personally notified of the modification, as well as the reasons for making it.
	Subsection (8) places an obligation on the Secretary of State, or senior official acting on their behalf, to remove an operational purpose where selection for examination of data for that purpose is no longer necessary.
	Subsection (10) provides that where there is a need to make a major modification, but it is not reasonably practicable for the Secretary of State to sign the instrument making the modification, it can be signed by a senior official acting on behalf of the Secretary of State, but the modification must be personally authorised by the Secretary of State. Such a modification is not an urgent modification and must still be approved by a Judicial Commissioner before taking effect.