Subject. The article is devoted to analysis of some issues concerning realization of adversary principal in proceedings in the Constitutional Court of the Russian Federation.Purpose. The purpose of the article is to analyze foreign experience of legal regulation of the status of constitutional court process participants as parties and/or interested persons in constitutional court proceeding, to give arguments in favor of introducing the category of ‘interested privies’ in Russian legislation regulating constitutional court proceedings.Methodology. The author uses theoretical analysis as well as legal methods including formal legal analysis and the method of legal comparison.Results, scope of application. Law often does not specify the party opposing the claimant during the proceedings in the Constitutional Court of the Russian Federation. The need to introduce the adversary principal in such cases requires to introduce the category of ‘interested privies’, whose rights and duties may be affected during the case solution in the Constitutional Court of the Russian Federation.The following persons and entities may become interested privies in Constitutional proceedingst: persons whose claims brought against the decision of intergovernmental body for protecting human rights and freedoms - in cases on possibility of executing the decision of intergovernmental body for protecting human rights and freedoms; the State Duma and the Council of Federation of the Federal Assembly of the Russian Federation as bodies participating in ratification of the treaty - in cases on the check of constitutional legitimacy of a treaty about accepting new subject into the Russian Federation; constitutional bodies and public offices whose constitutional legal status may be changed as a result of official interpretation of constitutional rules - in cases on interpreting the Constitution; the RF Central Election Committee - in cases on the check of constitutional legitimacy of an issue introduced for the referendum of the Russian Federation; the President of the Russian Federation (if the request comes from the Supreme Court of the Russian Federation); the State Duma, the Supreme Court of the Russian Federation, President of the Russian Federation - in cases on providing the ruling about the observance of the established rules public prosecution of the President of the Russian Federation for treason or another serious offence.

Conclusions. The category ‘interested persons’ will enable to provide guarantee of fair trial in resolving constitutional court conflicts, if such category would be included into Russian legislation.