Dual nationality was already prohibited in the first citizenship law of Ukraine in 1918.1 This regulation stipulated that the acquisition of another nationality would result in the loss of Ukrainian nationality.2 In addition, if a person had become a citizen of another state without permission, they should have been prohibited from returning to Ukraine.3 In accordance with the prevailing regulations, Ukraine does not prohibit dual nationality; instead, it acknowledges single nationality. Article 4 of the Constitution states that ‘[t]here is single citizenship in Ukraine.’4 Article 2 of the Law on Citizenship of 2001 lays out the principles of Ukrainian legislation on citizenship. This law is based on the principle of single citizenship, which means: ‘citizenship of the State of Ukraine that rules out the possibility for existence of a citizenship of administrative-territorial units of Ukraine. If a citizen of Ukraine has acquired the citizenship of (allegiance to) another state or states, then in legal relations with Ukraine such person shall be recognised as a citizen of Ukraine only. If a foreigner has acquired the citizenship of Ukraine, then in legal relations with Ukraine he/she shall be recognised as a citizen of Ukraine only.’5