jected to qualified thresholds (see para. 220 et seq. below).
c) Based on the above considerations, the instrument of strategic surveillance, including the use of formal search terms targeting specific individuals and the collection
and analysis of traffic data, sometimes in its entirety, is not in principle incompatible
with Art. 10(1) GG or the proportionality requirements resulting therefrom. However,
given that it is not based on specific grounds and essentially guided and restricted
only by the purpose pursued, the power to conduct strategic surveillance is an exceptional power that must be restricted to foreign surveillance conducted by an authority
that itself has no operational powers for averting dangers to public security. It can
only be justified by the authority’s particular tasks and the specific conditions under
which these tasks are performed. In accordance with the principle of proportionality,
the specific design of this power must be in line with these considerations.
166
2. The legislative design of data collection and processing in the framework of
strategic surveillance is subject to further requirements, which must take into account
the particular weight of the interferences with fundamental rights and the specific justification provided by the particular task and conditions of foreign surveillance.
167
a) An overarching aim of the requirements arising from the principle of proportionality is to limit strategic telecommunications surveillance by ensuring that it is designed
as a sufficiently focussed instrument despite its broad scope and indiscriminate effect. The Basic Law does not allow for global and sweeping surveillance, not even for
the purpose of gathering foreign intelligence (cf. BVerfGE 100, 313 <376>).
168
Therefore, the legislator must restrict the volume of data to be taken from the respective transmission channels ([…]) and the geographical area covered by surveillance. Since the technical possibilities for processing data are changing quickly,
merely referring to actual capacity limits in this respect is insufficient ([…]). Yet above
all, the legislator must circumscribe the powers in accordance with the rule of law so
as to structure and partially restrict data collection and processing. In particular, this
includes rules on the use of filtering techniques (see b) below), the purposes of surveillance (see c) below), the design of the surveillance process (see d) below), the
focused use of search terms (see e) below), the limits of traffic data retention (see f)
below), the methods of data analysis (see g) below), the protection of relationships of
trust (see h) below) and the protection of the core of private life (see i) below), as well
as the imposition of obligations to delete data (see j) below). In addition, the legislator
must adhere to requirements regarding transparency, individual legal protection and,
above all, extensive independent oversight (for general considerations on this, see V.
below).
169
b) Given that strategic surveillance can only be justified as an instrument for gathering foreign intelligence, further data processing must be based on clear provisions
requiring that data stemming from domestic communications be removed.
170
aa) Provisions on the removal of data stemming from telecommunications in which
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