Introduction. The article is devoted to the study of the role of modern constitutional law in the system of sectoral legal sciences. The author notes that jurisprudence in general is a formal science, the subject of which are formal systems, which, mainly, it postulates itself - specific branches of law. Until a certain period (the formation of the Constitutional Court of the Russian Federation and the adoption of the new Constitution of the Russian Federation) state law could also be considered as a sectoral science, the subject of which was mostly the system of state power organisation. However, unlike mathematics (which is also a formal science), jurisprudence possesses regulatory potential and relates to the impact on human behavior. In this way it cannot be encapsulated exclusively in the system of legal constructions outside the «life world». Research methods. A set of methods was used in the work: analysis and synthesis, induction and deduction, dialectical approach, method of comparative jurisprudence. Results. The author proves that the special role of constitutional law in the modern stage of development is that, on the one hand, through processes of constitutionalisation of other branches of law constitutional law claims to be a general system. In a certain sense, the science of constitutional law is gradually taking the place of theory of law in legal epistemology.