The Latin American Integration Route (RILA) is a proposal for regional development based on the economic, political, and social integration of Latin American countries. Its objective is to better develop the interaction between countries and the utilization of regional resources and opportunities, aiming at strengthening economic and social development. Integration Law is the field of International and Community Law responsible for governing relations between countries during the implementation of regional integration. It encompasses the norms and principles regulating the commercial, political, cultural, and social relations among the member countries of RILA. In this context, the main goal of this article is to present conceptual aspects of Integration Law and Harmonization of Law, and to reflect on their roles within the context of Latin American integration. The current text is a qualitative approach and bibliographical research, drawing from thinkers that bring the Integration Law and Harmonization of Law scheme to the regional economic integration scenario. It comes to the conclusion that International Law is fundamental to the maintenance and economic integration of the member countries of MERCOSUL, since it creates norms and principles by which the members of this bloc (nations and civil society) can guide themselves.