The purpose of the new citizenship law which was proposed by the new German federal government was to give legal aliens living in Germany a choice to become German citizens without having to give up the nationality which was conferred on them by their parentage or descent. This thesis will question whether this rigid concept should be completely abolished after an assessment of both the constitutionality and the exact implications of the new citizenship law. In the light of the conclusions, the comparative part of this thesis will then focus on a more general approach and will compare the concepts of nationality and domicile with special emphasis on their practical application in both common and civil law jurisdictions. First, there will be a presentation of the different common law jurisdictions and the way each defines and applies the concept of domicile. Next, the author compares the merits and drawbacks of both the nationality and the domicile concept. Finally, the thesis analyzes whether one of the concepts of domicile found in the various common law jurisdictions is likely and fit for a solution of the citizenship law problem. In the final chapter, this thesis presents the concept of habitual residence which could become a connecting factor in the future of private international law and will broaden the inquiry to whether there is a chance for convergence of the common and civil law jurisdictions on that particular connecting factor at some point in the future.