tutional law to also collect the data in question for the changed purpose using comparably intrusive means (cf. BVerfGE 141, 220 <327 et seq. para. 287 et seq.>).
However, special circumstances must be taken into consideration for the constellation at hand. While authorities usually collect data specifically for their own operational purposes and the data is then used for a new purpose when it is shared with
other authorities, the Federal Intelligence Service does not collect data for its own
operational purposes, but merely with the aim to share it with the Federal Government and, as the case may be, other bodies after having identified and processed the
relevant information (cf. § 1(2) BNDG). Moreover, the powers to collect data in question here are not tied to objective thresholds but are essentially only guided by the
purpose pursued.
217
Especially for this constellation, adherence to substantial requirements regarding
data sharing is thus of great significance. Data collection for the purpose of foreign
surveillance does not require verifiable thresholds so as to allow for the identification
of and proactive search for threats and situations of danger as purely precautionary
measures long before specific dangers (konkrete Gefahren) actually arise. Under
constitutional law, this requires that such thresholds must apply at least to the sharing
of intelligence thus obtained ([…]). The purpose of data collection and the purpose of
data sharing converge: The Federal Intelligence Service has far-reaching powers to
gather intelligence to enable it to identify important information from a large volume
of largely unstructured data before any operational actions are taken. A key purpose
of data collection is the distinction between relevant and irrelevant data, which determines what information is provided to the government and, as the case may be, further bodies that have executive powers. However, the provisions on data sharing
must then ensure that intelligence obtained on the basis of powers that are essentially not tied to specific grounds can only be used further if it were permissible, under
the general requirements arising from the rule of law, to collect the data for the purposes for which the shared data is to be used .
218
Thus, whether the sharing of data is constitutional depends on whether it were permissible, under constitutional law, to collect the data for the purpose for which the
shared data is to be used using comparably intrusive means (cf. BVerfGE 141, 220
<328 para. 288>). Since it is impermissible from the outset to make an instrument
which is as sweeping as telecommunications surveillance that is not based on specific grounds available to domestic security authorities, the constitutional requirements that are also applicable to other particularly severe and intrusive measures
such as the surveillance of private homes or remote searches apply (cf. BVerfGE
141, 220 <271 para. 110; 273 and 274 paras. 115 and 116; 327 et seq. para. 287 et
seq.>), unless measures merely serve to provide reports to the Federal Government
(see para. 223 et seq. below). This is in line with, and further determines, the requirement of an exceptionally significant public interest and of sufficiently specific and
qualified thresholds for data sharing that the Federal Constitutional Court laid down
in its decision on the Counter-Terrorism Database in relation to the sharing of infor-
219
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