The article states that the implementation of the ideas of the fundamental values of a democratic state is possible only when there will be a reliable mechanism of control over the power. Such control is a prerequisite not only legitimize public authorities, but also human rights. The author uses the concept of three periods in the historical development of democracy J. Keane (assembly democracy, representative democracy and controlling democracy), stressing that the control mechanisms of democracy provide protection from the tyranny of the majority, responsive to the output power beyond its mandate. It is noted at the required connection control public authority with the rule of law through the institutions of national sovereignty, separation of powers, representative government, limited and responsible governance, constitutional and administrative review. Emphasized that the important factors in the implementation of social control in a democratic state are such elements as elections, referendums, public movements and organizations, political parties, independent media, public opinion, various forms of social protest. The tendency to increase the role of private institutions in the exercise of public power in the modern world is stated.