The article presents a monistic concept of the relationship between national criminal procedural law and international law, in particular, comparing the norms of international treaties, the Constitution of Ukraine, and the Criminal Procedure Code of Ukraine. The places of these legal norms in the hierarchy of the country's legal system are determined from the point of view of their different legal force.
 Such an institution of the national criminal-procedural branch of law as interference in private communication is considered. It was analyzed that compliance with the norms of this institute includes classic and non-typical legal norms of the CPC of Ukraine. A scientific opinion is presented regarding the incompleteness of the list of investigative actions provided for by the prescriptions of paragraph 2 "Interference in private communication" of chapter 21 "Secret investigative (search) actions" of the CPC, which are related to interference in private communication.
 The legal category "private communication" was analyzed, in particular the legal definitions set forth in Part 1 of Art. 3 Art. 258 of the CPC of Ukraine, theoretical aspects of the essence of this concept, its constituent elements. The latest judicial practice of the Supreme Court on the application of this legal category was studied.
 It was concluded that the content of the research definition includes private, family and professional spheres, and may include information that is in the possession of a mass media or journalist, medical, notarial, commercial or other legally protected secret.
 In the context of the study, the provisions of Part 1 of Art. 8 and Part 1 of Art. 10 of the Convention on the Protection of Human Rights and Fundamental Freedoms. The legal category "private communication" is compared with the concept of "correspondence" of this Convention, which is interpreted in the practice of the European Court of Human Rights. Different approaches of national and international law to the formation of formed legal categories are noted.
 The provisions when the right to respect for "correspondence" must be ensured, that is, the confidentiality of communication must be protected, in accordance with the practice of the European Court of Human Rights.
 Focused attention on the relationship between Articles 8 and 10 of this Convention in situations where special powers are used to circumvent the protection of journalistic sources.
 The similarity of the researched concepts of private communication and correspondence, which under certain features may be similar in their own essence, after the violation relate to the protected right to secrecy of communications, has been established.