Law enforcement agencies play an important rolein ensuring internal security and protecting thesuperiority of law. In order to ensure the executionof this duty, law enforcement officers are equippedwith a number of special authorizations such assearch, seizure, use of force and use of weapons,unlike other public officials. Due to the potential ofthe use of such powers to violate the fundamentalrights and freedoms of people, law enforcementpersonnel are also supervised by some internaland external mechanisms. In addition to the supervision by hierarchical control and disciplinaryboards, civilian oversight by legislative, executiveand judicial bodies, administrative authorities,independent boards, the public, the media andnon-governmental organizations is also very important. Within the scope of the research, one of the components of civilian oversight ‘independent lawenforcement complaint systems’ have been examined. Countries with specialized institutionstasked with investigating complaints against law enforcement officers; Belgium, Denmark, Englandand Wales, Ireland, Scotland, Northern Ireland,Luxembourg, Hungary, Malta and Norway from themember states of the Council of Europe and alsoinstitutions in South Africa, Canada, Kenya and NewZealand have been examined in a comparativemanner by benefiting from establishment laws,corporate websites, performance programs and annual reports within some criterias such as authority,resource, independence, transparency, reportingand civil society participation. Some suggestionshave been made to increase the effectiveness ofthese systems. Although there are some examplesin accordance with the principles of “independent,impartial and civil structure”, it has been seen thatthere is a need for some reforms that will increasethe effectiveness of the system.