145. The establishment, implementation and application of the powers and procedures provided for in this Section of the Convention shall be subject to the conditions and safeguards provided for under the domestic law of each Party. Although Parties are obligated to introduce certain procedural law provisions into their domestic law, the modalities of establishing and implementing these powers and procedures into their legal system, and the application of the powers and procedures in specific cases, are left to the domestic law and procedures of each Party. These domestic laws and procedures, as more specifically described below, shall include conditions or safeguards, which may be provided constitutionally, legislatively, judicially or otherwise. The modalities should include the addition of certain elements as conditions or safeguards that balance the requirements of law enforcement with the protection of human rights and liberties. As the Convention applies to Parties of many different legal systems and cultures, it is not possible to specify in detail the applicable conditions and safeguards for each power or procedure. Parties shall ensure that these conditions and safeguards provide for the adequate protection of human rights and liberties. There are some common standards or minimum safeguards to which Parties to the Convention must adhere. These include standards or minimum safeguards arising pursuant to obligations that a Party has undertaken under applicable international human rights instruments. These instruments include the 1950 European Convention for the Protection of Human Rights and Fundamental Freedoms and its additional Protocols No. 1, 4, 6, 7 and 12 (ETS N°s 005 (4), 009, 046, 114, 117 and 177), in respect of European States that are Parties to them. It also includes other applicable human rights instruments in respect of States in other regions of the world (e.g. the 1969 American Convention on Human Rights and the 1981 African Charter on Human Rights and Peoples’ Rights) which are Parties to these instruments, as well as the more universally ratified 1966 International Covenant on Civil and Political Rights. In addition, there are similar protections provided under the laws of most States.
146. Another safeguard in the convention is that the powers and procedures shall “incorporate the principle of proportionality.” Proportionality shall be implemented by each Party in accordance with relevant principles of its domestic law. For European countries, this will be derived from the principles of the 1950 Council of Europe Convention for the Protection of Human Rights and Fundamental Freedoms, its applicable jurisprudence and national legislation and jurisprudence, that the power or procedure shall be proportional to the nature and circumstances of the offence. Other States will apply related principles of their law, such as limitations on overbreadth of production orders and reasonableness requirements for searches and seizures. Also, the explicit limitation in Article 21 that the obligations regarding interception measures are with respect to a range of serious offences, determined by domestic law, is an explicit example of the application of the proportionality principle.
147. Without limiting the types of conditions and safeguards that could be applicable, the Convention requires specifically that such conditions and safeguards include, as appropriate in view of the nature of the power or procedure, judicial or other independent supervision, grounds justifying the application of the power or procedure and the limitation on the scope or the duration thereof. National legislatures will have to determine, in applying binding international obligations and established domestic principles, which of the powers and procedures are sufficiently intrusive in nature to require implementation of particular conditions and safeguards. As stated in Paragraph 215, Parties should clearly apply conditions and safeguards such as these with respect to interception, given its intrusiveness. At the same time, for example, such safeguards need not apply equally to preservation. Other safeguards that should be addressed under domestic law include the right against self-incrimination, and legal privileges and specificity of individuals or places which are the object of the application of the measure.
148. With respect to the matters discussed in paragraph 3, of primary importance is consideration of the “public interest”, in particular the interests of “the sound administration of justice”. To the extent consistent with the public interest, Parties should consider other factors, such as the impact of the power or procedure on “the rights, responsibilities and legitimate interests” of third parties, including service providers, incurred as a result of the enforcement measures, and whether appropriate means can be taken to mitigate such impact. In sum, initial consideration is given to the sound administration of justice and other public interests (e.g. public safety and public health and other interests, including the interests of victims and the respect for private life). To the extent consistent with the public interest, consideration would ordinarily also be given to such issues as minimising disruption of consumer services, protection from liability for disclosure or facilitating disclosure under this Chapter, or protection of proprietary interests.