This chapter focuses on the restricted character of international public policy and on the fact that though it belongs to each State, many of its fundamental principles are enshrined in human rights conventions and private international law conventions and therefore are shared by all the States Parties to that convention, which enables the integration and articulation of diversity, at either a regional or a universal level. Consequently, the identification of those shared fundamental principles should increase the predictability of results in private international law cases and soften the barrier that the public policy exception imposes regarding foreign laws and judgments. Notwithstanding this, the aforementioned statements do not mean that the role of the public policy exception will disappear. In order to develop this argument, this chapter explains some key concepts such as those of international and domestic public policy, a posteriori and a priori public policy, their differences and similarities. It examines how public policy evolves over time alongside society and how that evolution is reflected in statutory and conventional rules.