The International Public Law theory constitutes a part of the international law science, just as an area of science in statu nascendi. This theory represents a set of statements logically and systematically organized, that is, the sums of knowledge about the International Public Law order. Its research aims are, above all, the essence of International Public Law, its functions, its system and structure, its principles and rules, the customary international law, the general principles of law, the rules hierarchy, the formation and imposition of rules, the branches and institutes of the International Public Law and, last but not least, its relations with other components of the International Public Law (philosophy, methodology, sociology, dogmatic and). This paper seeks to open the path towards a deep research of the international law science through a basic investigation. Likewise, it attempts to formulate a solid conception of the International Law science.