Apart from the common techniques intelligence services use in carrying out their activities and gathering information, there are also special intelligence techniques that can be used. However, it is essential that the way they are used and the reasons for their use always comply with the law. The Slovak Information Service is authorized to use special techniques to collect information in order to fulfill its duties set forth in the Protection against Wiretapping Act 166/2003. When the Service uses the special techniques, it can infringe upon the rights and freedoms of citizens only to the extent and manner established by the above-mentioned law. The special techniques include operational-intelligence techniques and technical-intelligence techniques. The Slovak Information Service is required to protect them from any disclosure or misuse and keep records on their use. Under the Slovak Information Service Act, the Operational-Intelligence techniques include: a) surveillance of persons and events, b) legally authorised alias documentation, c) the use of persons acting on behalf of the Information Service. The Director, or a deputy delegated by him, shall decide on the use of surveillance by the Information Service in performing its duties within the scope of its activities. Legally authorised alias documentation are documents and things serving to conceal the true identity of an officer. Identity cards of representatives of the National Council of the Slovak Republic, of members of the Government of the Slovak Republic, and official identity cards of judges and prosecutors cannot be used as legally authorised alias documentation. A person acting on behalf of the Information Service is a natural person who willingly and in a covert manner offers his or her services to the Information Service in the fulfilment of its tasks. According to the Protection against Wiretapping Act, technical intelligence techniques include primarily electro-technical, radio-technical, photo-technical, optical, mechanical, and other technical means and equipment or their components used in a covert manner in: a) the search for, opening and examination of transported packages and examining them by using forensic methods, b) the intercepting and recording of telecommunications transmissions, c) making and using visual, audio, and other recordings. In a democratic society technical intelligence techniques can be used only in cases concerning protection of security and defence of the state, preventing and investigating criminal activities and protection of rights and freedoms of citizens. The initiation and use of technical information techniques shall limit the rights and freedoms of citizens only when unavoidable and only to the necessary extent required. Information collected by technical information techniques shall be used exclusively for achieving the objective. Technical intelligence techniques shall be used only on the basis of previous written permission from a judge and only for a set period of time, lasting no longer than six months. The term shall go into effect on the day the permission is granted. If it is necessary to use simultaneously or consequently more than one technical intelligence technique, each shall be used to the extent permitted. If technical intelligence techniques are to be used in places, not open to the public, a judge must decide whether the permission applies to those places.