Judgment Approved by the court for handing down.
“93. ... foreseeability in the special context of secret
measures of surveillance, such as the interception of
communications, cannot mean that an individual should
be able to foresee when the authorities are likely to
intercept his communications so that he can adapt his
conduct accordingly (see, inter alia, Leander v. Sweden,
judgment of 26 August 1987, Series A no. 116], p. 23, §
51). However, especially where a power vested in the
executive is exercised in secret, the risks of arbitrariness
are evident (see, inter alia, Malone, cited above, p. 32, §
67; Huvig, cited above, pp. 54-55, § 29; and Rotaru). It is
therefore essential to have clear, detailed rules on
interception of telephone conversations, especially as the
technology available for use is continually becoming
more sophisticated (see Kopp v. Switzerland, judgment of
25 March 1998, Reports 1998-II, pp. 542-43, § 72, and
Valenzuela Contreras v. Spain, judgment of 30 July 1998,
Reports 1998-V, pp. 1924-25, § 46). The domestic law
must be sufficiently clear in its terms to give citizens an
adequate indication as to the circumstances in which and
the conditions on which public authorities are empowered
to resort to any such measures (see Malone, ibid.; Kopp,
cited above, p. 541, § 64; Huvig, cited above, pp. 54-55, §
29; and Valenzuela Contreras, ibid.).
94. Moreover, since the implementation in practice of
measures of secret surveillance of communications is not
open to scrutiny by the individuals concerned or the
public at large, it would be contrary to the rule of law for
the legal discretion granted to the executive or to a judge
to be expressed in terms of an unfettered power.
Consequently, the law must indicate the scope of any
such discretion conferred on the competent authorities
and the manner of its exercise with sufficient clarity to
give the individual adequate protection against arbitrary
interference (see, among other authorities, Malone, cited
above, pp. 32-33, § 68; Leander, cited above, p. 23, § 51;
and Huvig, cited above, pp. 54-55, § 29).
95. In its case-law on secret measures of surveillance, the
Court has developed the following minimum safeguards
that should be set out in statute law in order to avoid
abuses of power: the nature of the offences which may
give rise to an interception order; a definition of the
categories of people liable to have their telephones
tapped; a limit on the duration of telephone tapping; the
procedure to be followed for examining, using and storing
the data obtained; the precautions to be taken when
communicating the data to other parties; and the
circumstances in which recordings may or must be erased
Davis & Ors v SSHD