The scope of regulation of social relations connected with both secular and canon laws are of great interest for the researchers. In particular, these relations are linked to the constitutional presumption of the separation of the church and the state. At the same time, there is a tendency of convergence of the church and the state in matters concerning property, correlation of church and secular education, etc. The clergy by virtue of the nature of their professional duties, mostly deal with private and personal information and it is also a sphere of common interest for both the state and the church. The use of the comparative legal research methods, methods of the analysis and synthesis of the situation have made it possible to match the norms of the canon and secular law and identify some elements of their relations. The main purpose of the article is the comprehensive study of the seal of confession, its conceptual framework, legal regulation, judicial practice, forms and types of responsibility for its violation. This paper examines historical facets of development of the seal of confession, beginning with the Spiritual Regulations and up to the modern ecclesiastical and secular norms. The Spiritual Regulations were specific since they contained no absolute inviolability of the seal of confession as soon as the information concerned the security of higher officials. The paper also highlights the legal framework of the secrecy of the confessional, being some professional religious mystery, on the one hand, as well as a legal mode and a form of some sensitive or restricted information, on the other. The Fundamentals of the Social Concept of the Russian Orthodox Church contain the requirements and tell the priest how to classify the information communicated to him by his parishioner. The article focuses on some features of the seal of confession practice abroad, particularly in Germany and the USA. Eventually, the US laws provide for the circumstances where the communication of the clergy and their parishioners should remain confidential. There are, however, some requirements compelling the priest to report whenever protection of children is involved. The jurisprudence supports the rules regulating the seal of confession. Three relevant cases have been studied by the authors and they involve the separation of secular and religious laws.