In what ways is sovereignty an international institution? Many would argue that it is such a nebulous and contested concept that it has no fixed or essential meaning or application in international life. But if we think of sovereignty as a set of practices, ideas, beliefs, and norms, its significance as a foundational international institution becomes clearer. Without it, the life of political communities, even if organized into states, would be vitally different. Consider some of the common individual and state practices that we take for granted, yet are the consequences of sovereignty. At the individual level, when a traveler commits a crime in a foreign country, he or she is immediately subject to the host's laws. He or she cannot appeal to some other authority for protection or release. That same traveler does not stop to ponder why a passport is necessary to enter another country. It is just done, and that is the way things are. But passports are a creation of the twentieth century (although they existed shortly during the French Revolution as well). They are an expression of sovereignty in the sense that they identify the citizenship of the bearer, which means that he or she has differential rights based on location. The passport does not confer anyone's right to enter a country. The host can exclude anyone it wants. So we travel abroad because governments agree to let us enter. Consent is a critical fact of sovereignty.