French professor Gaudemet-Tallon has described the modern theory of Private International Law by two symbols: the funambulist and the rainbow. (le funambule et l'arc-en-cie) The development of modern theories of Choice of Law rules are now more and more complex than what they were in the last century. The trends of pluralism pushes the scholars not only to expand their research field, but also review a very basic question: what is the main idea of the Private International Law in this modern world?This article tries to prove, from the angle of internationalism and judicial practices, that opening the procedure of Choice of Laws rules to the parties can not only reduce the risk of arbitrariness of Judge, but also provide an efficient solution, which conciliates the different interests and values in the litigation. Actually, all legal theory shall inevitably ask a basic and fundamental question: will the controversy be subsided by our choice? Consequently, what we need is an open, plural and flexible structure/solution which can handle the various international affairs in the ”real” modern international society, and this structure shall never be satisfied on an image such as ”stability” or ”certainty” from another ”pure theory” world.