§ 301. The fourth and fifth modes of acquiring nationality are by subjugation after conquest and by cession of territory, the inhabitants of the subjugated as well as of the ceded territory acquiring ipso facto by the subjugation or cession the nationality of the State which acquires the territory. These modes of acquisition of nationality are modes settled by the customary Law of Nations; it will be remembered that details concerning this matter have been given above, §§ [219] and [240].
Seven modes of losing Nationality.
§ 302. Although it is left in the discretion of the different States to determine the grounds on which individuals lose their nationality, it is nevertheless of interest for the theory of the Law of Nations to take notice of these grounds. Seven modes of losing nationality must be stated to exist according to the reason of the thing, although all seven are by no means recognised by all the States. These modes are:—Release, deprivation, expiration, option, substitution, subjugation, and cession.
(1) Release. Some States, as Germany, give their citizens the right to ask to be released from their nationality. Such release, if granted, denationalises the released individual.
(2) Deprivation. According to the Municipal Law of some States, as, for instance, Bulgaria, Greece, Italy, Holland, Portugal, and Spain, the fact that a citizen enters into foreign civil or military service without permission of his Sovereign deprives him of his nationality.
(3) Expiration. Some States have legislated that citizenship expires in the cases of such of their subjects as have emigrated and stayed abroad beyond a certain length of time. Thus, a German ceases to be a German subject through the mere fact that he has emigrated and stayed abroad for ten years without having undertaken the necessary step for the purpose of retaining his nationality.
(4) Option. Some States, as Great Britain, which declare a child born of foreign parents on their territory to be their natural-born subject, although he becomes at the same time according to the Municipal Law of the home State of the parents a subject of such State, give the right to such child to make, after coming of age, a declaration that he desires to cease to be a citizen. Such declaration of alienage creates ipso facto the loss of nationality.
(5) Substitution. Many States, as, for instance, Great Britain, have legislated that the nationality of their subjects extinguishes ipso facto by their naturalisation abroad, be it through marriage, grant on application, or otherwise. Other States, however, as, for instance, Germany, do not object to their citizens acquiring another nationality besides that which they already possess.
(6) Subjugation and cession. It is a universally recognised customary rule of the Law of Nations that the inhabitants of subjugated as well as ceded territory lose their nationality and acquire that of the State which annexes the territory.[624]
[624] See above, § [301]. Concerning the option sometimes given to inhabitants of ceded territory to retain their former nationality, see above, § [219].