"The International Space Station (ISS) is the most politically and operationally complex space exploration program ever undertaken" and without any doubt, the ISS program is one of the most successful multilateral projects in addition to the fact that this is the greatest accomplishment as a human space program. In considering the legal future of multilateral big projects including that of the ISS after 2020, this paper reviews the ISS program to evaluate which elements have brought a success and which elements have to be thought less than successful or even should be changed in its future operation. To evaluate the ISS/IGA and relevant instruments of international nature, this paper studies how the present ISS/IGA and relevant instruments have been developed from the historical standpoint, for the present instruments cannot be the only logical consequence: it should rather be the combination of the reality of international cooperative mechanism involving huge resources and the specific historical background. Cross-waiver of liability, rules on exchange of data and goods and intellectual property as well as the principle that each partner bears financial responsibility for its own tasks are concluded as duly established practice to operate an ISS now and in the future. However, it is pointed out that some rules including the criminal jurisdiction and registration, jurisdiction and control could be provided for in a different way depending on the partners, projects and international ramification.