‘Each State Party shall permit the renunciation of its nationality provided the persons concerned do not thereby become stateless.’ 8 Under Article 15 of the European Convention on Nationality: ‘The provisions of this convention shall not limit the right of a State Party to determine in its internal law whether: a b 9 its nationals who acquire or possess the nationality of another State retain its nationality or lose it; the acquisition or retention of its nationality is subject to the renunciation or loss of another nationality.’ Pursuant to Article 16 of that convention: ‘A State Party shall not make the renunciation or loss of another nationality a condition for the acquisition or retention of its nationality where such renunciation or loss is not possible or cannot reasonably be required.’ European Union law 10 Article 20 TFEU states: ‘1. Citizenship of the Union is hereby established. Every person holding the nationality of a Member State shall be a citizen of the Union. Citizenship of the Union shall be additional to and not replace national citizenship. 2. Citizens of the Union shall enjoy the rights and be subject to the duties provided for in the Treaties. They shall have, inter alia: (a) the right to move and reside freely within the territory of the Member States; …’ Austrian law 11 Paragraph 10 of the Staatsbürgerschaftsgesetz 1985 (1985 Austrian Law on Citizenship) (BGBl. 311/1985), in the version applicable to the dispute in the main proceedings (‘the StbG’), provides: ‘(1) Except as otherwise provided for in the present federal law, citizenship may be granted to an alien only if … 6. on the basis of his conduct hitherto, the alien guarantees that he has a positive attitude towards the Republic and neither represents a danger to law and order or public security nor endangers other public interests as referred to in Article 8(2) of the [European Convention for the Protection of Human Rights and Fundamental Freedoms, signed in Rome on 4 November 1950]; … (2) An alien may not be granted citizenship … 2. … if he has been the subject of more than one enforceable conviction for a serious administrative offence of a particular degree of gravity …