The author represents the research project of the Institute of Law and Public Policy (Moscow) concerning the main Russian constitutional principles and the results of their implementation in the past 20 years. On the basis of cognitive methodology and sociological approach he reconstructs the authentic meaning of such principles as pluralism, separation of powers, federalism, the independence of judicial power and guarantees of political rights and freedoms. He demonstrates the possibility to measure the level of constitutional deviances in each of them regarding such areas of constitutional practices as legislation, judicial decisions, administrative influence and the role of informal practices. The balance between constitutional stability and institutional changes is conceptualized as an empirical problem of the constitutional monitoring.