The social psychology of legal relations is a new scientific field. It develops at the meeting point of social and legal psychology. The main scientific problem in studying legal relations is associated with understanding the essence of law. Two leading directions have emerged in legal science: the doctrine of the natural and the social nature of law. In psychological terms, these doctrines reflect one of the main issues of psychology about the relationship between the biological and the social in the human psyche. The concept of the natural origin of law gives psychologists the opportunity to study law from the perspective of the biological foundations of the human psyche. The concept of the social nature of law (positive law) is linked to social psychology and orients psychologists towards the study of legal relations. In legal reality, there is a close relationship between natural law and positive law, which emphasises the unity of the biological and social essence of human beings. Theoretical analysis of the aspects of legal relations is determined by actual problems. Interest in the problems of legal relations is caused by the need to form a state governed by the rule of law and to establish a new system of legal relations in the global community. The Western legal and social psychology pays not much attention to the legal relations. The article analyses the concept of «legal relations» on the basis of national legal and socio-psychological literature. There is no consensus in jurisprudence regarding the definition of «legal relations». Legal relations are a form of social relations. Problems in the formation of consolidated legal relations are linked to insufficient knowledge in the field of law, especially among young people. When studying legal relations it is necessary to take into account psychological peculiarities of legal behavior. The article examines two socio-psychological aspects of the formation of legal relations. The first aspect is the interrelation of psyche and law, the second aspect is the connection of law with morality and ethics. The unity of law, morality and ethics is determined by the necessity of not only legal but also moral regulation of behavior. Philosophical and legal literature has comprehensively analysed the relationship between law and the human psyche. G. W. F. Hegel emphasised the psychological nature of law, since the phenomenon of law emerges as a result of the spiritual activity of a person. On this basis public legal relations originate. In Russian science, the doctrine of natural law and the relationship between psyche and law was developed by L. I. Petrazhitsky who focused his attention on the study of motives of legal behavior and developed the classification of human emotions. Positive law is psychologically expressed in the concepts of duty, responsibility and obligation. A socio-psychological analysis shows that the structure of legal relations is made up of cognitive, communicative and behavioral components. The social nature of law is determined by the moral foundations of society. Morality shapes the ideal of human behavior, while law determines the requirements for achieving that ideal.