Abstract: The object of this study is a set of legal relations arising in the organization of judicial structures and court structures based on the principles of singleness and collegiality. The subject of this study is the definition of the concepts of "judicial composition" and "composition of the court". The conducted research contributes in the future to the development of a system of theoretical ideas about the principles of collegiality and singleness in the organization of Russian justice, about the criteria for their implementation and the systemic links between these principles and other principles, as well as the development on the basis of proposals designed to correct the relevant provisions of the current legislation of the Russian Federation. The research method is comparative legal analysis, which allows to study the subject both from the standpoint of analytics and comparative studies. The result of the work are the author's definitions of "judicial composition" and "composition of the court". The scope of the results is the development of public law doctrine and current legislation governing the organization of justice in the Russian Federation. The scientific novelty of the research consists in enriching the conceptual apparatus that defines the elements of the justice system, as well as in suggesting a possible direction for reforming the current legislation of the Russian Federation regulating the organization of justice. The conclusion is that the proposed differentiation of concepts is designed to achieve both doctrinal uniformity and, in the legislative sphere, to help eliminate conflicts through unification. The introduction of these definitions into scientific circulation in the future may lead to changes in the relevant procedural codes.