One Territory, one State.
§ 171. The supreme authority which a State exercises over its territory makes it apparent that on one and the same territory can exist one full-Sovereign State only. Two or more full-Sovereign States on one and the same territory are an impossibility. The following five cases, of which the Law of Nations is cognisant, are apparent, but not real, exceptions to this rule.
(1) There is, first, the case of the so-called condominium. It happens sometimes that a piece of territory consisting of land or water is under the joint tenancy of two or more States, these several States exercising sovereignty conjointly over such piece and the individuals living thereon. Thus Schleswig-Holstein and Lauenburg from 1864 till 1866 were under the condominium of Austria and Prussia. Thus, further, Moresnet (Kelmis), on the frontier of Belgium and Prussia, is under the condominium of these two States[274] because they have not yet come to an agreement regarding the interpretation of a boundary treaty of 1815 between the Netherlands and Prussia. And since 1898 the Soudan is under the condominium of Great Britain and Egypt. It is easy to show that in such cases[275] there are not two States on one and the same territory, but pieces of territory, the destiny of which is not decided, and which are kept separate from the territories of the interested States[276] under a separate administration. Until a final settlement the interested States do not exercise each an individual sovereignty over these pieces, but they agree upon a joint administration under their conjoint sovereignty.
[274] See Schröder, "Das grenzstreitige Gebiet von Moresnet" (1902).
[275] The New Hebrides are materially likewise under a condominium, namely, that of Great Britain and France, although article 1 of the Convention of October 20, 1906—see Martens, N.R.G. 3rd Ser. I. (1909), p. 523—speaks only of "a region of joint influence" with regard to the New Hebrides. See Brunet, "Le Régime International des Nouvelles-Hebrides" (1908), and Politis in R.G. XIV. (1907), pp. 689-759.
[276] As regards the proposed condominium over Spitzbergen, see Waultrin in R.G. XV. (1908), pp. 80-105, and Piccioni in R.G. XVI. (1909), pp. 117-134.
(2) The second case is that of the administration of a piece of territory by a foreign Power, with the consent of the owner-State. Thus, since 1878 the Turkish island of Cyprus has been under British administration, and the then Turkish provinces of Bosnia and Herzegovina were from 1878 to 1908 under the administration of Austria-Hungary. In these cases a cession of pieces of territory has for all practical purposes taken place, although in law the respective pieces still belong to the former owner-State. Anyhow, it is certain that only one sovereignty is exercised over these pieces—namely, the sovereignty of the State which exercises administration. On the other hand, however, the fact that in these cases pieces of territory have for all practical purposes been ceded to another State does not empower the latter arbitrarily to annex the territory without the consent of the State owning it in law. Austria-Hungary had therefore no right to annex, in 1908, without the previous consent of Turkey, the provinces of Bosnia and Herzegovina.[277]
(3) The third case is that of a piece of territory leased or pledged by the owner-State to a foreign Power. Thus, China in 1898 leased[278] the district of Kiauchau to Germany, Wei-Hai-Wei and the land opposite the island of Hong-Kong to Great Britain, and Port Arthur to Russia.[279] Thus, further, in 1803 Sweden pledged the town of Wismar[280] to the Grand Duchy of Mecklenburg-Schwerin, and the Republic of Genoa in 1768 pledged the island of Corsica to France. All such cases comprise, for all practical purposes, cessions of pieces of territory, but in strict law they remain the property of the leasing State. And such property is not a mere fiction, as some writers[281] maintain, for it is possible that the lease comes to an end by expiration of time or by rescission. Thus the lease, granted in 1894 by Great Britain to the former Congo Free State, of the so-called Lado Enclave, was rescinded[282] in 1906. However this may be, as long as the lease has not expired it is the lease-holder who exercises sovereignty over the territory concerned.