can take place “at scale” and “cover a large geographic area”. Nonetheless, it is
true of these warrants as it is of their EI equivalents that they have some of the
potential range of bulk warrants but without the same safeguards: the comments
at 2.52-2.58 below are therefore of relevance here also.
How bulk interception works
2.13.
Interception is the process of collecting communications in the course of transit,
such that the content becomes available to someone other than the sender or
recipient. The fruits of interception (the main focus of which must be overseasrelated: clause 129(2)) can include both the content of such communications and
information about them. Bulk interception typically involves the collecting of
communications as they transit particular bearers (communication links).64
2.14.
Bulk interception involves three stages, which may be called collection, filtering
and selection for examination.65
First stage: collection
2.15.
GCHQ selects which bearers to access based on an assessment of the likely
intelligence value of the communications they are carrying. GCHQ does not have
the capacity, or legal authority, to access every bearer in the world. Instead it
focuses its resources on those links that it assesses will be the most valuable. At
any given time, GCHQ has access to only a tiny fraction of all the bearers in the
world.
Second stage: filtering
2.16.
GCHQ's processing systems operate on the bearers which it has chosen to
access. A degree of filtering is then applied to the traffic on these bearers,
designed to select communications of potential intelligence value while
discarding those least likely to be of intelligence value. As a result of this filtering
stage, the processing systems automatically discard a significant proportion of
the communications on the targeted bearers.
Third stage: selection for examination
2.17.
64
65
The remaining communications are then subjected to the application of queries,
both simple and complex, to draw out communications of intelligence value.
Examples of a simple query are searches against a “strong selector” such as a
Bearers are explained in the 2015 ISC Report, p.26 at fn 48. There were then c. 100,000
bearers joining up the global internet. The ISC gave the example of 47 separate 10 gigabit per
second bearers carried in a single transatlantic cable, but noted that the capacity of both
bearers and cables is expanding fast as technology develops.
Further information is given (I believe accurately, though with many redactions from the open
version) in the 2015 ISC Report, para 49-77.
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