The concept of international law has many facets. In the past, sovereign states, the Holy See, and corporations were the only parties subject to international law. However, the definition of international law has expanded to include organizations and individuals. International human rights law, for example, has been extended to include corporations. And there are even treaties prohibiting the use of cluster munitions. In addition to the many definitions of international law, this body of law contains a large number of specific rules governing the use of such weapons.

The study of international law is often accompanied by debates about the nature of the relationship between international law and national sovereignty. Many people view the nation-state as the primary unit in international affairs. Furthermore, many scholars hold that only states are authorized to enter into or interpret international agreements. Thus, international law has a strong impact on national sovereignty, but there are also significant differences between public and private international law. If international law is practiced inconsistently, it can lead to harm to national interests.

Regardless of its origins, international law comes from the interactions between states, nations, and their people. There is no single supreme government that can establish international law, and treaties are one of the most common sources of international law. But even today, customary international law is a useful tool for settling international conflicts. The existence of a common language and a cultural tradition can be important in resolving disputes between states. It can also be useful in the context of international trade.