We will apply a new institutional theory to the legal relationships of regional integration in the legal sphere.Systems of unified or harmonized legal norms create a territory with a unified legal system in respect to economic matters.A patchwork of different legal systems is no adequate instrument for economic entities willing to operate beyond the borders of their own state.By agreeing onto clear, precise and binding rules of procedure representing a set "supranational legal rules", regional organizations lower the interaction costs between states, legal entities and other legal subjects.Homogeneity of legal norms reduces transaction costs throughout the geographical area concerned by such homogenization process (Wagner 2009).In modern times, the proliferation of different national regimes represents an obstacle to the economic activities of legal subjects.For example, Carbonara and Parisihighlited the problems of "legal distance" (i.e., the degree of difference) between different nation legal systems(Carbonara, Parisi 2007 p.372) and a bigger legal distance between countries is the source of higher transaction costs.(Ib.)"Legal distance" between countries can be shortened by three different methods-unification, harmonization of law in the way of cooperative concerted action of the concerned states, or transplantation of law of a given state as a unilateral action by another state.All three methods may eliminate "institutional and judicial costs",that according to Dani Rodrik still exist nowadays not only as a restriction directly imposed by states,but as the indirect result of"long legal distance"(Rodrik 2004).