Key Threats of Statelessness in the Post-Secession sudanese 239 arbitrary unless it serves a legitimate purpose and complies with the principle of proportionality. Thus, article 8 of the Convention on the Reduction of Statelessness allows for a limited set of circumstances under which deprivation of nationality resulting in statelessness is permissible, but as exceptions to a general principle they must be narrowly construed.12 There is, however, considerable state practice supporting the involuntary substitution of nationality in the context of state succession.13 As explained by Hudson, If the effects of the cession on the nationality of the inhabitants of the ceded territory are regulated by treaty, such treaties usually provide that the nationality of the predecessor State is lost by the conferment of nationality by the successor State. Where the transfer of territory and the conferment of nationality is in accordance with international law, the predecessor State is obliged to recognize it. Its sovereignty has been replaced by that of the successor State (…)14 Habitual residence is the test most frequently used to assess the connection between the individual citizen and a successor state.15 This test achieves two key policy goals. First, it ensures that individuals in receipt of citizenship have 12 13 14 15 Report of the Secretary-General (n 10), para 51. Manley O Hudson, ‘Report on Nationality, Including Statelessness’ UN Doc No. A/CN.4/50 Yearbook of the International Law Commission 1952, Vol II, para 10; ‘Germany undertakes to recognise any new nationality which has been or may be acquired by her nationals under the laws of the Allied and Associated Powers and in accordance with the decisions of the competent authorities of these Powers pursuant to naturalisation laws or under treaty stipulations, and to regard such persons as having, in consequence of the acquisition of such new nationality, in all respects severed their allegiance to their country of origin.’ Treaty of Versailles 28 June 1919, art. 278; Paul Weis refers to this process as “substitution”: ‘(…) automatic loss of nationality upon acquisition of another nationality (…) by operation of law (…)’ Paul Weis, Nationality and Statelessness in International Law (2nd edn, Sijthoff & Noordhoff International Publishers BV 1979) 116. Hudson (n 13), para 11. Patrick O’Connell, State Succession in Municipal and International Law Vol I (CUP 1967) 518; see e.g. Republic of Kosovo Law Nr. 03/L-034 On the Citizenship of Kosovo, art. 29 (‘Citizenship according to the Comprehensive Proposal for the Republic of Kosova Status Settlement’) ‘29.1 All persons who on 1 January 1998 were citizens of the Federal Republic of Yugoslavia and on that day were habitually residing in Republic of Kosova shall be citizens of Republic of Kosova and shall be registered as such in the register of citizens irrespective of their current residence or citizenship.’ tilburg law review 19 (2014) 236-247