Abstract: The subject of this research is the sources of formation of a subject domain as well as conceptual and methodological bases of comparative law in ancient philosophical and legal discourse. The authors address to the heritage of Ancient Greek and Ancient Roman philosophy of law, reveal specifics of antique legal thinking, offer sociocultural and mental assessment of its contents and orientation of development of the latter. They emphasize the importance of the Ancient comparative and legal discourse for the formation and development of legislative, law-enforcement and right interpretative practice of the past and the present. In their research the authors have used historical and legal and comparative and legal methods. As the methodological strategy of the research they have used the discourse approach offered by M. Foucault who insisited that the appeal to the research of various sociocultural phenomena including the state and legal phenomena and processes should be realized in terms of of acting social practices that influence the essence of the latter. For these research objectives, the authors have described a number of social practices that predetermined the development of both public, and hidden comparative and legal discourses which defined formations and development of the classical Ancient philosophy and law. In their research the authors have described particular features of the formation and development of a subject domain and methodlogical grounds of of comparative law in Ancient socio-cultural and political and legal scenarios. They have proved that Greek and Roman concepts of the political and legal relaities, their forms and means of constructing legal terms and practical tools became a substantive beginning and course of an original and unique European (and later EuroAmerican) legal universum.