Foreign direct investment (“FDI”) is an important feature of globalization and hence is signiﬁcant for the economic development of all countries. International investment law, which relates to and regulates FDI, should be able to promote and encourage it among all countries in the world. The fast growing number of bilateral investment treaties (“BITs”) and free trade agreements (“FTAs”) that offer protection and preferential treatment to foreign investments and investors evidences the trend. As in other aspects of human society, obligations and rights stipulated in BITs and FTAs are closely linked with each other. In other words, where a person or a group of persons has a given right, another person or group of persons must have a corresponding obligation. Under international investment law, it is the host states which apparently assume the bulk of the obligations, whilst foreign investors are entitled to the corresponding rights. For instance, where a host state is obliged not to treat foreign investments and investors arbitrarily or not to expropriate foreign investments without compensation, a foreign investor is entitled to be treated accordingly and, if it is not, it may claim that the host state in question has breached its international obligations.