18 DRAGOJEVIĆ v. CROATIA JUDGMENT held, in cases nos. U-III-621/2005 and U-III-4921/2013, that a constitutional complaint could not be lodged directly against an indictment. III. RELEVANT INTERNATIONAL MATERIAL 62. The relevant part of the Recommendation Rec(2005)10 of the Committee of Ministers to member States on “special investigative techniques” in relation to serious crimes including acts of terrorism of 10 April 2005 reads: “Chapter I – Definitions and scope For the purpose of this Recommendation, “special investigation techniques” means techniques applied by the competent authorities in the context of criminal investigations for the purpose of detecting and investigating serious crimes and suspects, aiming at gathering information in such a way as not to alert the target persons. For the purpose of this Recommendation, “competent authorities” means judicial, prosecuting and investigating authorities involved in deciding, supervising or using special investigation techniques in accordance with national legislation. Chapter II – Use of special investigation techniques at national level a. General principles 1. Member states should, in accordance with the requirements of the European Convention on Human Rights (ETS No. 5), define in their national legislation the circumstances in which, and the conditions under which, the competent authorities are empowered to resort to the use of special investigation techniques. 2. Member states should take appropriate legislative measures to allow, in accordance with paragraph 1, the use of special investigation techniques with a view to making them available to their competent authorities to the extent that this is necessary in a democratic society and is considered appropriate for efficient criminal investigation and prosecution. 3. Member states should take appropriate legislative measures to ensure adequate control of the implementation of special investigation techniques by judicial authorities or other independent bodies through prior authorisation, supervision during the investigation or ex post facto review. b. Conditions of use 4. Special investigation techniques should only be used where there is sufficient reason to believe that a serious crime has been committed or prepared, or is being prepared, by one or more particular persons or an as-yet-unidentified individual or group of individuals. 5. Proportionality between the effects of the use of special investigation techniques and the objective that has been identified should be ensured. In this respect, when deciding on their use, an evaluation in the light of the seriousness of the offence and taking account of the intrusive nature of the specific special investigation technique used should be made.