The research focuses on the relationship between law and multiculturalism from a historical perspective, especially in relation to the medieval period: how interactions between different ethnic, linguistic and religious groups in the medieval period contributed to the formation of the legal system. An excellent case study is represented by medieval Sicily where at least four different cultures (Latin, Greek, Arab and Jewish) cohabited. The starting point is the consideration that legal multiculturalism profoundly influenced the production and construction of the legal system. The research tries to ascertain how legal demands from below have been brought into balance with rules imposed from above (i.e. from the central power). The aim is to demonstrate that legal norms were formed through the continuous interaction between these two poles.