The article investigates the concept and essence of constitutional law as a legal category, the appointment of the Federal Constitutional Law in the legislation of the Russian Federation and its place in the hierarchy of rules of law, the relationship of federal constitutional laws with the constitution and other legal acts. The article defines the specific features and characteristics of the federal constitutional laws. The study discusses the features of the use of constitutional law at the federal level and at the level of the republics within the Russian Federation, notes differences in the appointment of federal constitutional laws at the federal level and the appointment of the Federal Constitutional Law on the level of the Federation of the number of republics within the Russian Federation. The article also aims at setting the consideration of problems associated with the uncertainty of the category of constitutional law in the Russian Federation, considering the lack of a clear definition, the contradictions in the interpretation of the limits of use of inconsistency in law enforcement.