The article introduces the limits of conceptual analysis of law, and the possibilities of functional and multidisciplinary approaches to law. It sketches some stations of the history of legal philosophy emphasizing spreading multidisciplinary tendencies of the philosophy of law. It illuminates some connection of various scientific approaches on the basis of a concrete research relating to the religious roots of Roman law. Finally it outlines vertical and horizontal structures of multidisciplinary legal research, which are based on the ontological levels of reality and special scientific interests.