ABSTRACT
Dual citizenship has rapidly increased all over the world in the past decades. More and more sovereign states tolerate or even accept multiple nationalities for various reasons (Goldstein and Piazza, 1996). Even in countries such as Germany, which do not tolerate dual citizenship as a rule, about one-fourth to one-third of all naturalisations from the 1970s through the 1990s resulted in multiple citizenship (Beauftragte der Bundesregierung, 1999, p. 27).2 This is a puzzling state of affairs. Until very recently, public opinion and political theory regarded citizenship and loyalty to a nation as indivisible. Yet the new developments now raise doubts that border-crossing ties and loyalities of citizens violate the principle of popular sovereignty and contradict full sovereignty claimed by national and multinational states.
