The basic concepts and related problems of the theory of constitutional law are considered, such as: the Constitution, the Constitutional Law (basic law), the subject of constitutional regulation (constitutional relations), the methods of constitutional regulation, the concept of constitutional law and a number of others. It is noted that the purpose and the fundamentality of constitutional research, which derives from this, should be manifested in the study of the “man-state” relationship, where the state’s provision of basic human rights is the goal and the structure of state power is the duty of the state, a means of properly safeguarding basic human rights. It is proposed to distinguish between the concepts of “basic law” and “constitution” where the basic law is only a special external (textual) form of expression of constitutional relations, and the Constitution is the basic human rights, which are the highest value and subject to recognition, observance and protection by the state, as stipulated by Art. 2 Of the Russian Constitution. Consequently, an objective (not formal) criterion that allows the constitutional law to be singled out in the system of legislation is its purpose to guarantee basic human rights, through recognition, compliance and protection by all branches of government (legislative, executive and judicial). It is proposed in determining the substance of constitutional regulation, as indeed any legal regulation, to abandon the normative understanding of the law.