Complex states and state communities are states that make up several political-territorial units. Even in the ancient period we encounter forms of association of states. The main reason for connecting in the past, was defense. By complex states we mean: federation, confederation, personal union, real union, legislative union and asymmetric communities of states. Personal and real union are a thing of the past. These are the communities of rulers of two states that occur when the successor ranks coincide or when the ruler of one state is elected as the ruler of another state. The main difference between personal and real union is in the relation of permanence of connection per person of the ruler. The most important example of a personal union is the personal union of Croatia with Hungary (1102.-1527.), and the real union is the Austro-Hungarian Monarchy. The differences between a federation and a confederation are significant. Eg. In the case of the confederation, the legal basis of the community is the treaty of international law, and in the case of the federation, the constitution of the federation. A confederation is not a subject of international law while a federation is. In a legislative union, the constituent parts find their constitutional expression through common institutions. Asymmetric communities of states are based on asymmetric forms of constitutional order. A stronger and larger state ensures that the weak and the smaller preserve integrity and autonomy. The European Union is a new form of state union, it is unique in the integration of European countries with which it strengthens its internal integration. It was created in 1994 by the Maastricht Treaty. In this case, the Member States and the European Union itself can legislate. A special form of a complex state is Bosnia and Herzegovina, which is a complex federal state with elements of a confederation. It functions as a protectorate, under the protection and supreme supervision of the international community. It consists of two entities: Republika Srpska and the Federation of Bosnia and Herzegovina, and there is also the Brcko District. The presidency consists of three members.