The evolution of the international landscape requires a similar evolution of International Law in order to fully implement the principle of effectiveness. It is an essential tool: according with this principle, the acceptance of the norm by society as a whole gives it irresistible force. Since international society has undergone deep changes, while legal rules have remained unchanged, in order to stem the crisis of International Law, it is necessary to engage the diplomatic channels of all economic and political powers, rebuilding a new form of multilateralism shared by today’s international community. In a context of deep revision of multilateralism and new forms of international legal cooperation, it will also be necessary to address the issue of the role of private entities, which do not yet have a clear formal status under International Law but possess considerable economic power. The main challenge is to align private interests with public interests, an essential prerequisite for private entities to engage actively in regulatory processes and international legal cooperation by making substantial capital available.