The subject matter of the research is the legal category of subinstitutes of law. The author formulatesthe definition of the substitute of law addressing the essence of scientific classification in general andin law in particular. Reasons are given as to the objective necessity in carrying out scientific researchin this area as they may contribute to theoretical and practical aspects. Classifying will let considerthe legal category of subinstitutes from different angles in detail. In turn, it will promote to refiningthe concept and attributes of subinstitute and further the ultimate recognition of subinstitute as anintegral part of Russian legal system. The research is seen relevant as Russian legal science lacksthe background for the problem. The paper calls for embarking an academic discussion on this issueas it is vital to set up its clear interpretation. Further, the research studies versions of classifications forthe legal category in question. Various criteria are proposed to search for the types of subinstitutes oflaw in Russian legal system. The classifications are supported with practical examples. The conclusionpresents the summation of the carried out research. The classifications are the first step in developing aclear scientific attitude on this problem. Further, challenging and accurate research is required to set upthe final list of possible classifications in question. Due to the dynamic development of public relationsand hence legal system, the discussion mentioned cannot be postponed. Theory should assist practiceand as we see subinstitutes of law are part of Russian legal system. However, an insufficient theoreticalstudy of the legal category, in particular in classifying, may hinder its functioning in practice or evencause breakdowns in legal system, which is inadmissible.