There are several ways to think about law. In the domestic legal system, we think of law as the rules that the government issues to control the lives of its citizens. Those rules are generally created by the legislature, interpreted by the judiciary, and enforced by the executive branch, using the police, if necessary, to force citizens to obey. What is law for the international community if there is no one legislature, judiciary, executive branch, or police force?

Imagine a school playground with several children at play. The “law” is the set of playground rules that the teacher tells her students. For example, she might tell them, “Don’t hit your classmate.” Two different reasons can explain why the children will follow this rule. On the one hand, they may follow the rule only because they are afraid of being punished by the teacher. On the other hand, the students may believe that it is a bad thing to hit their classmates. Since it is a bad thing to do, they will follow the teacher’s rule.

In the first case, they will obey the rule only if the teacher is there and ready to punish them. In the second case, students will obey the rule even if the teacher is not there. In fact, even if the teacher is not present, the children may obey the rule because they have become used to not hitting each other and have therefore enjoyed playing with each other.

Just as certain common understandings between children may make it easier for them to play, collective agreement on certain rules can often serve the interests of all the members of a community. Just as on a playground without a teacher, in the international setting there is no central authority. For the most part, however, states will follow the rules they have agreed to follow because it makes their interactions easier than not following those rules.

Thus, the fact that there is no overall authority to force compliance with the rules does not necessarily mean that there is no law. Law still exists in this setting, though it may be practiced and enforced in different ways. International law can therefore be called “real law,” but a special type of law with different characteristics from the law practiced in domestic settings, where there is a legislature, judiciary, executive, and police force.