In simple terms, the Department of Internal Security is a “defense department”. Oversight activities of the Department of Internal Security focus on protecting the Service against activities and phenomena potentially threatening its internal security, e.g. it protects the BIS against potential infiltration by foreign intelligence services.
Furthermore, the Department of Internal Security detects attitudes and activities violating internal service regulations unacceptable for a Service officer. The Department investigates cases of classified information leaks and vets applicants for BIS officers. Moreover, in compliance with Act No. 412/2005 Coll., on the Protection of Classified Information the Department screens BIS officers and is in charge of protecting the Service as a whole.
Basically, the activities of the Department of Internal Security are based on the Act on the Protection of Classified Information requiring the BIS to comply with provisions in the areas of physical, administrative and personnel security, and in the area of information and communication system security.