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Investigatory Powers Commissioner’s Annual Report 2019
Thematic warrants
8.27
We examined a number of thematic targeted interception warrants where applications
had been made for both major and minor modifications to add new subjects and factors.
All were properly authorised and consistently completed to a very high standard, with a
clear rationale for adding or removing factors. Each modification clearly demonstrated the
necessity and proportionality case as well as linking the new factor or individual to the
subject and purpose of the warrant. If there was any change in potential collateral intrusion
as a result of a new factor being added this was clearly addressed. There was good
evidence that factors were being deleted promptly when no longer required, demonstrating
good housekeeping.
Definition: factors
A factor is a description used to identify the communications to be intercepted under a warrant
such as an address, a number or piece of apparatus. This could include a postal or email
address, a telephone number or a device’s Media Access Control (MAC) address.
General descriptors
8.28
The IPA allows for the use of “general descriptors” in circumstances where it is not practical
to name or describe all of the subjects at the point the warrant is issued. The Interception
and EI Codes of Practice (CoP) advise that the practicability of providing individual names or
descriptions will need to be assessed on a case by case basis and will depend, for example,
upon the existing intelligence picture, the scale and pace of the operation, the nature of the
communications to be intercepted and/or from where secondary data is to be obtained,
the nature of the factors (or equipment to be interfered with) and the time constraints of
the particular operation.
8.29
We reviewed a number of warrants which included general descriptors. Overall, MI5
officers provided clear justification for why they needed this type of warrant and the
flexibility of adding new subjects under the general descriptor. In some earlier applications
we noted a degree of confusion as to what was necessary to justify the use of a general
descriptor with some applications focussing on why all of the potential future subjects of
the warrant were not identified yet, or the fact that, at the point MI5 required coverage
of new subjects, they may not be fully identified. This is not relevant to the question
MI5 is required to address. Rather, the use of a general descriptor should be justified
in the application taking account of both the IPA’s other requirements on necessity and
proportionality and the guidance in the CoP that the overall intrusion to be authorised
must be clear to the issuing authority at the time the warrant is issued. We saw no such
confusion in more recent applications.
Testing and training warrants
8.30
Section 17(2)(c) of the IPA provides for agencies to obtain interception warrants for
testing and training purposes, whilst sections 101(1)(g) and (h) provides for warrants for
the testing, maintenance and development of equipment interference capabilities and
training in the use of such capabilities. In 2019 MI5 applied for small number of training
and testing warrants under the IPA. All but one of these superseded pre-existing warrants
(including one which was put in place to supersede several earlier authorisations including
non-IPA warrants).