The international legal framework governing foreign investment consists of an extensive network of international investment treaties (IIGF) supplemented by general regulations of international law. Although other international treaties interact with this network, PII is a major public international legal instrument governing the promotion and protection of foreign investment. PII regulates the relationship between foreign investors and the government of the host country. International Investment Treaties act as key instruments for countries in the world to attract and manage Foreign Investment. International investment treaties are instruments of international law that countries use to regulate their relations in the field of investment. Through IIGF, countries want to create a stable international legal instrument to facilitate and protect the flow of foreign investment and increase the growth of the national economy. Based on the above background, this article aims to reconceptualize investment treaties as treaties that can balance the interests of state sovereignty and investment protection. Therefore, methodologically, this article describes the conceptual framework for the application and interpretation (de lege lata) of PII so that it can balance state sovereignty and investment protection. However, when viewed from the perspective of investors, the premise is opposite or vice versa, that is, if the state is given complete freedom to exercise its authority in full, then the investment treaty system will not provide adequate guarantees to investors to promote efficient investment. Therefore, international investment law has core functional similarities with domestic administrative and constitutional reviews of government actions at both the domestic and international levels, including under various human rights instruments, such as the European Convention on Human Rights. From a functional perspective, international investment law is therefore a discipline of public law.