Luuk van der Baaren 2. Citizenship constellations So far, this report has analysed national restrictions of dual citizenship taken separately. However, dual citizenship can only occur if two states concurrently permit dual citizenship. Therefore, provisions related to dual citizenship should be studied in cohesion, or as ‘citizenship constellations’. The term ‘citizenship constellations’ was coined by Bauböck and aims to “[…] [bring] into view how host and home countries create a web of legal and political ties with migrant and ethnic kin groups that also affects intergovernmental relations and public policy reform in each country”.20 The concept of citizenship constellations will be applied in this report in order to outline the extent of dual citizenship acceptance in the European Union. Although the concept has a broader connotation, it will be used here in a narrow sense, focusing on the interactions between legal provisions in receiving countries and sending countries that potentially restrict dual citizenship. More precisely, the interactions between provisions requiring the renunciation of the original citizenship upon acquisition of citizenship (A05-A27) and provisions imposing the (automatic or non-automatic) loss of original citizenship upon acquisition of another citizenship (L05) will be studied for the 28 EU Member States. Thereby, it will be elucidated whether both the receiving country and the sending country in a particular citizenship constellation allow for the occurrence of dual citizenship. One could argue that studying the acquisition of dual citizenship among EU Member States is a needless exercise, as the status of EU citizenship already grants a ‘bundle of rights’ across all Member States (see Section 2). However, as will be shown below, the number of EU citizens acquiring citizenship of another Member State is far from negligible, and therefore deserves special attention. In Table 2, each cell depicts whether a state (referred to in column) requires the renunciation of origin citizenship upon acquisition of citizenship and whether a state (referred to in row) imposes the loss of original citizenship upon acquisition of another citizenship on the reference date of 31 December 2018. If the renunciation of the original citizenship is not required in any case for that particular constellation and if the loss of citizenship upon acquisition of another citizenship is also not imposed in any case for that particular constellation, the cell is marked grey. In all other cases, the cell is unmarked. An important caveat is that many important nuances of dual citizenship restrictions cannot be taken into account in this manner. For example, certain states (e.g. the Netherlands and Spain) do not restrict dual citizenship for all relevant modes of acquisition of citizenship (A05-A27), but only for some of these modes. Other states (e.g. Austria) in principle restrict dual citizenship, yet permission can be granted for the retention of citizenship in individual cases. Therefore, if a cell has remained unmarked, this merely indicates that dual citizenship is potentially restricted for a particular constellation. In order to also depict the numerical significance of each citizenship constellation, the number of persons who acquired citizenship in the reference year of 2018 is depicted for each particular constellation on the basis of data provided by Eurostat on the acquisition of citizenship.21 Another caveat is necessary here, as it has remained unclear which data citizenship acquisitions is provided to Eurostat by EU Member States, as the data requirements 20 Bauböck, R., “Studying citizenship constellations”, Journal of ethnic and migration studies, Vol. 36, No. 5, 2010, p. 849. 21 European Commission, “Acquisition of citizenship (2018)” [data file], Eurostat, 2020, via <eurostat.ec.europa.eu>. RSCAS/GLOBALCIT-Comp. 2020/4 - © 2020 Authors 7