Meijers Committee standing committee of experts on international immigration, refugee and criminal law legal standards on non-discrimination in relation to dual nationals; these standards are then applied to the case of citizenship deprivation (paragraph 7). Paragraphs 8 and 9 present our conclusions and recommendations. We submit that these findings can be relevant for other less extreme forms of unfavourable treatment of dual nationals. 2. Dual nationality: causes, acceptance and occurrence of dual nationality During the first post-war decades, dual nationality was considered a problematic exception to the general rule that a person could and should only have close relations with one state and, thus, one nationality. The 1963 Council of Europe Convention on the Reduction of Cases of Multiple Nationality reflected this dominant idea. In recent decades, dual nationality has become more acknowledged. In 1990 dual nationality was accepted in 5 out of 18 Western European states and in 2010 in 14 of those 18 states.9 In 2020, only Austria and the Netherlands are mutually bound by the rules against dual nationality in the 1963 Convention. The 1997 European Convention, ratified by 13 EU Member States, is the expression of a development to a more liberal position towards multiple nationalities, a recognition of the fact that persons can have legal and emotional relations with more than one country.10 The main causes of dual nationality are migration, equal treatment of men and women in nationality law (children in mixed marriages acquiring one nationality from their mother and another from their father), integration policies and ius soli rules.11 In Germany, since 2000, children of lawfully settled non-German parents acquire German nationality at birth next to the nationality of their parents. The obligation for these German nationals to choose between their two nationalities, once they become of age, was de facto abolished in 2014.12 In Belgium and the Netherlands, the third generation acquires Belgian or Dutch nationality at birth even if both parents are non-nationals.13 Thus those children, generally, are dual nationals at birth. This development is also reflected in the increasing number of exceptions to the rule, still in force in some European states, that applicants for naturalisation have to give up their original nationality. The German Constitutional Court concluded in 2008 that recent changes in the legislation indicated that reduction of dual or multiple nationality got less priority and that private interests in the acquisition or retention of dual nationality got the same weight as the public interest in avoiding dual nationality.14 Between 2015 and 2018, approximately 60% of those who naturalised in Germany retained their first nationality.15 In the Netherlands, about 9 Y. Harpaz and P. Mateos, ‘Strategic citizenship: negotiating membership in the age of dual nationality’, Journal of Ethnic and Migration Studies 2019, p. 843-857. 10 See R. Bauböck et al (eds) (2006), Acquisition and Loss of Nationality: Policies and Trends in 15 European States: Comparative Analyses, Amsterdam: Amsterdam University Press; T. Faist (ed.) (2007) Dual Citizenship in Europe, Aldershot: Ashgate; D.Thränhardt (2017), Einbürgerung im Einwanderungsland Deutsland, Bonn, Fredrich-Ebert-Stiftung, p. 24 and M. Vink, ‘The international diffusion of expatriate dual citizenship’, Migration Studies 2019, p. 362-383, https://doi.org/10.1093/migration/mnz011. 11 H.U. Jessurun d‘Oliveira, ‘De normaliteit van dubbele nationaliteit’, Asiel & Migrantenrecht 2019, p. 432-440. 12 Act of 13 November 2014, Bundesgesetzblatt. I, p. 1714. 13 Art. 3(3) Rijkswet op het Nederlanderschap; Art. 11 Wetboek van de Belgische nationaliteit/Code de la nationalité belge. 14 Bundesverfassungsgericht 10 April 2008, 14 BVerwGe, 5 C 28.07. 15 12. Lagebericht der Integrationsbeauftragten (2019) Berlin, Bundesministerium des Innern, table 14, p. 150. 3