tematic collection of telephone customer data is of indispensable added value for the
security authorities in contrast to access to other data sets. It is also proportionate in
the narrow sense. Its unquestionable benefit stands against an encroachment which
has little weight. Finally, § 111 TKG does not provide for an impermissible data retention, for the provision defines the purpose with sufficient clarity in referring to public
security.
The statutory amendments referred to by the complainants extend the duties of collection and storage to other line identification numbers in order to react to the fact that
today the stored telephone numbers alone are insufficient to guarantee that the subscriber data can be determined, for example because other identifiers are also issued
in DSL technology. In this way, the collection of customer data is extended to include
a new phenomenon, without acquiring a new quality. The duty to store the device
numbers of mobile telephones is also only a reaction to a de facto phenomenon
which threatens to defeat the purpose of the information on customer data. For if persons charged with an offence use more than one mobile phone card for only one mobile phone, information relating to the line is no longer sufficient. The storage of customer data in connection with email services serves to implement Directive 2006/24/
EC. It takes account of the fact that the identifier of an email account has now become
a fundamental identification feature of accessibility in telecommunications, comparable to telephone number and address.
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f) § 112 TKG is also in conformity with the Basic Law. The encroachment upon the
right to informational self-determination constituted by automated information on
telecommunications customer data may be attributed to § 112 TKG only to a limited
degree, since the legal relationship between the security authority and telecommunications customers is shaped by the non-constitutional law which contains the authorising provisions for data collection. The only duty of § 112 TKG is to support the nonconstitutional authorising provision with a retrieval procedure and a duty to make data
available, but not to formulate the relevant threshold of encroachment. In addition,
§ 112.2 TKG defines the criterion of necessity, as an additional condition for encroachment. The encroachment is insignificant, since it affects basic identification data with a low degree of personal relevance and a high degree of social reference. For
this reason, the secrecy of the retrieval does not have the same weight as in other
combinations of circumstances. The question as to how far the person affected is to
be informed of retrievals of customer data or how far the person affected has a right of
information, on the other hand, is to be answered by non-constitutional law. In addition, in mass procedures in the case of insignificant encroachments there is no constitutional duty of notification. The subsequent use of the data obtained under § 112 is
based on the relevant non-constitutional law of the requesting authorities, which contains corresponding limitations to specific purposes.
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The possibility contained in § 112.1 sentence 4, 112.3 TKG of using incomplete
search data or a search with a similarity function is unobjectionable. Admittedly, the
search may have a certain range, but the encroachment even here is insignificant,
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