Feud and blood feud are topics, which have been given a fair share of attention by researchers all over the world. The focus so far has been on anthropological research, based on collecting oral testimonies and less focus has been given to collecting various archival sources, which is a basic technique for interdisciplinary and interpretative studies of the social phenomenon mentioned and which should be correlated to general historical and civilizational development of society and law.The revenge itself is not merely protection of one's honor, which is also in contemporary society one of the pillars of the value of human dignity and represents a fundamental constitutional element of community as well as a social control and legal norm, which were developed and formed accordingly to development of society, culture and under the influence of the environment in which it was created.Therefore, the focus of the research project will be the area of Upper-Adriatic in the late Medieval and early Modern Age, due to area's unique intertwining of cultural, political and social impacts (influences of Greek, Roman, Slavic, Venetian, Habsburg and Ottoman culture), especially considering the interaction between urban and rural communities, their customs and legal norms. This signifies that the focus will be on comparative study of feud between customary law and (codified) legal process, i.e. the basis for the development of common law and civil law in countries under the influence of European justice culture.In this area, due to historical and environmental circumstances, customary law remained in practice and in the oral tradition, collected and recorded in the 19th and 20th century, which together with abundance of preserved archival material and legal documents, represents excellent starting point for the comparative studies of the development of law and general civilizational relations within this research field in Europe and in the World.