Meijers Committee standing committee of experts on international immigration, refugee and criminal law dual nationals can avoid differential treatment by giving up their second nationality.63 It was also submitted that dual nationality does not constitute a suspect discrimination ground under German constitutional law.64 With regard to indirect discrimination on the ground of racial or ethnic origin, it has been argued that this is not a problem as the German provision, unlike French law, does not distinguish between German citizens by birth and those who obtained German citizenship through naturalisation.65 Finally it was argued that to prohibit differential treatment of single and dual nationals would amount to an absolute prohibition of citizenship deprivation.66 For a discussion of these arguments see paragraph 7. 6. International instruments relevant for the lawfulness of differential treatment of citizens with dual or multiple nationality The focus of this paragraph is on international instruments relevant for our central question: does less favourable treatment of citizens with dual or multiple nationality amount to legally prohibited discrimination? - European Union Discrimination on the ground of nationality Article 21(2) of the EU Charter of Fundamental Rights and Article 18 TFEU both provide that any discrimination on grounds of nationality is prohibited, within the scope of application of the treaties. To date, these prohibitions have been interpreted to apply to situations where a national of one Member State is treated in a discriminatory manner as compared with a national of another Member State. Differentiations between EU citizens and third-country nationals are not covered.67 The Court of Justice has not ruled yet on the question whether the provisions also apply to distinctions between single and dual nationals. Articles 21(2) CFR and 18 TFEU apply to differences in treatment within the scope of application of the treaties. Assuming that distinctions between single and dual nationals are covered, these provisions could apply, for example, in the situation where a dual DutchTurkish national moves to Germany from the Netherlands – thus making use of the right to free movement – and faces differential treatment with regard to social security benefits or tax advantages on account of having a second nationality. With regard to the loss of nationality, the CJEU has made it clear that this comes within the scope of EU law when it results in the loss of EU citizenship and the rights attaching thereto.68 Assuming that Articles 18 TFEU and 63 Expert opinion by Ph. Wittmann presented to the Deutscher Bundestag on 24 June 2019, see footnote 57. Expert opinion by D. Thym presented to the Deutscher Bundestag on 24 June 2019, see footnote 57. 65 D. Thym, ‘Bürger zweiter Klasse im Einwanderungsland?’, Die Verwaltung 52 (2019) 3, p. 423. 66 Idem. 67 CJEU 4 June 2009, Vatsouras and Koupatantze, C-22/08 and C-23/08, EU:C:2009:344, paras 51-52 ; CJEU 7 April 2011, Francesco Guarnieri & Cie, C-291/09, EU:C:2011:217, para 20; General Court 20 November 2017, Udo Voigt v. European Parliament, T-618/15, EU:T:2017:821, paras 80-81 and General Court 20 November 2017, Andrei Petrov and others v. European Parliament, T-452/15, EU:T:2017:822, paras 39-40. 68 CJEU (GC) 2 March 2010, Rottmann, C-135/08, EU:C:2010:104, para 42 and CJEU (GC) 12 March 2019, Tjebbes and others, C-221/17, EU:C:2019:189, para 32. 64 12