The first supervisory control is performed at the level of the Internal Security Service (KAPO), above all in regard to the justification of initiating surveillance proceedings. Surveillance proceedings are very resource demanding, both in terms of workforce and finances. Therefore it is obviously not possible to cover all threat sources by surveillance activities and relevant choices need to be made already at the agency level. There is no option with respect to initiating criminal proceedings - if an act has elements of criminal offence, proceedings have to be initiated.
In order to ensure compliance with the Acts, supervisory control is also exercised over the personnel within the agency.
The activities of the Internal Security Service are additionally supervised by a number of other agencies exercising executive, judicial and legislative power:
- The Government of the Republic and the Public Prosecutor' s Office. The Ministry of Internal Affairs performs supervisory control over the activities related to the collection of information and surveillance of all agencies within its area of government, including the Estonian Internal Security Service, without intervening in criminal proceedings. The Internal Security Service reports about its activities to the Government of the Republic twice a year. The Prosecutor's Office in its turn exercises supervision over surveillance activities in criminal proceedings. In criminal matters it is possible to perform surveillance activities only with the knowledge and consent of the Prosecutor's Office.
- Judicial supervision. The surveillance activities infringing fundamental human rights most shall be performed only with the consent of the court and at the reasoned request of the prosecutor.
- The Chancellor of Justice and the State Audit Office. The Chancellor of Justice monitors the conformity of the activities of the Internal Security Service with the Constitution of the Republic of Estonia and other legal acts and any individual who perceives infringement of his/her constitutional rights and freedoms have the right to turn to the Chancellor of Justice. The State Audit Office monitors the legality of the use of budgetary means of the Internal Security Service.
- The Security Authorities Surveillance Select Committee of the Parliament, also popularly known as the "KAPO Committee". It exercises parliamentary supervision, constituting the highest authority that exercises supervision over the Estonian Internal Security Service.
Consequently, the Estonian Internal Security Service operates under the watchful eye of executive, legislative and judicial power. Supervision is continual, active and efficient, undoubtedly serving the best interests of both the Estonian Internal Security Service and the Republic of Estonia as a whole.