formational self-determination itself. Article 2.1 in conjunction with Article 1.1 of the
Basic Law does not prohibit every precautionary collection and storage of data whatsoever, but merely lays down special requirements for the justification of such precautionary data collections and subjects them to a restrained formulation (see BVerfGE 125, 260 <317>). In contrast, the storage of personal data for purposes that
are indefinite and cannot yet be determined is strictly prohibited (see BVerfGE 65, 1
<46>; 100, 313 <360>; 125, 260 <317>). But the present case does not relate to such
a storage of data, which is as a matter of principle impermissible. On the contrary, in
§ 111 TKG the legislature lays down a selective retention of particular data, restricted
in their scope and with a precisely defined information content, for the purposes defined in detail in §§ 112, 113 TKG. The supply structured in this way of a data basis
for specific information is not subject to this strict prohibition of data retention.
b) The collection and storage of the data governed by § 111 TKG is suitable to
achieve the legislative objective. § 111 TKG creates a data basis in order to be able
to attribute telecommunications numbers to their subscribers under §§ 112, 113. Admittedly, these data do not reveal who actually uses or has used the respective connection as a party to telecommunications. At all events, however, the relevant data
are clearly suitable as the starting point for further investigations. It is not necessary
that the goal of the legislation is actually attained in every case; for it to be suitable, it
is merely necessary that the attainment of the goal is facilitated (see BVerfGE 63, 88
<115>; 67, 157 <175>; 96, 10 <23>; 103, 293 <307>; 125, 260 <317-318>). The provision therefore does not fail the test of suitability for the reason that criminal offenders who wish to circumvent the provision sometimes use telecommunications services anonymously, under false names or with mobile phone cards acquired from
third parties, or because the customer data given by the users with regard to email
services remain unexamined and may therefore be false.
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c) The duty of storage of § 111 TKG is necessary to make reliable information possible. Admittedly, the data governed by § 111.1 TKG are predominantly stored by the
service providers in any case to conduct their contractual relationships under § 95
TKG. But § 111.1 TKG also ensures that data are available in cases in which their
storage is not necessary for the providers to conduct contractual relationships, as is
the case in particular with customers who use prepaid mobile phone cards.
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d) § 111 TKG does not violate the requirements of proportionality in the narrow
sense. Even if the provision orders a precautionary collection and storage, without
occasion, of a great range of telecommunications data, in view of the relatively restricted information content of the collected data this is an encroachment of limited
weight.
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aa) However, the encroachment is non-trivial. It has weight insofar as § 111 TKG
makes it possible to attribute telecommunications numbers and subscribers almost
completely for all telecommunications services and for this purpose individualising
data such as address, date of birth and date when the contract commences are
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