The legal framework of the foreign policy of the Byzantine in the era of Constantine VII Porphyrogenitus (945-959)

The aim of the article is to determine the legal foundations. The methodological basis of the study is analysis and synthesis, systems approach, genetic and comparative methods. Conclusions: The Byzantine law can be traced to the legislation of Basil I and Leo VI. However, jus gentium (law of nations) did not have sufficient representation in their codes. Therefore, the legal basis of Byzantine foreign policy consisted of customs and traditions that had been formed in diplomatic practice in ancient times.The system of international relations of Byzantium was hierarchical. The legal status of each participant in this system was determined by military power, political potential, tradition and religious identity. The relations between Byzantine and Kievan Rus’ can serve as a model of the application of international legal norms, which were based on the treaty of 944, which regulated the legal status of merchants, property rights, mutual military assistance and the use of territories on the coast of the Dnieper River estuary, Beloberezhye and the island of Saint Epherius (Berezan).