(2) As regards wireless telegraphy,[289] the "International Radiographic Convention," signed at Berlin on November 3, 1906, represents an agreement[290] of the signatory Powers concerning the exchange of radio-telegrams on the part of coast stations and ship stations, but it contains no stipulation respecting the question in general whether the territorial State is compelled to allow the passage over its territory of waves emanating from a foreign wireless telegraphy station. There ought to be no doubt that no such compulsion exists according to customary International Law, and that therefore the territorial State can prevent the passage of such waves[291] over its territory.
[289] See Meili, "Die drahtlose Telegraphie, &c." (1908); Schneeli, "Drahtlose Telegraphie und Völkerrecht" (1908); Landsberg, "Die drahtlose Telegraphie" (1909); Kausen, "Die drahtlose Telegraphie im Völkerrecht" (1910); Rolland in R.G. XIII. (1906), pp. 58-92; Fauchille in Annuaire, XXI. (1906), pp. 76-87; Bonfils, Nos. 53110 and 53111; Despagnet, No. 433 quater; Meurer and Boidin in R.G. XVI. (1909), pp. 76 and 261.
[290] See below, §§ [287]a, [287b], and [582, No. 4].
[291] The Institute of International Law—see Annuaire, XXI. (1906), p. 328—proposes by art. 3 of its "Régime de la Télégraphie sans fil" to restrict the power of the territorial State to exclude such waves from passing over its territory to the case in which the exclusion is necessary in the interest of its security.
(3) The space of the territorial atmosphere is of particular importance with regard to aviation, but no customary or conventional rules of International Law are as yet in existence which settle the very much controverted[292] matter. An international conference for the purpose of agreeing upon an international convention concerning aviation met in 1910 at Paris, but did not produce any result. The fact is that, since aviation is still in its infancy, practical experience is lacking concerning many questions which can only be settled when aviation has been more developed. It is tempting to apply the rules concerning the maritime belt and the Open Sea analogously to the space of the atmosphere, and, therefore, to distinguish between a zone of a certain height, in which the territorial State can exercise sovereignty, and, on the other hand, the atmosphere beyond that height, which is to be considered free like the Open Sea. This comparison between the atmosphere and the sea is, however, faulty for two reasons. Firstly, the Open Sea is an international highway that connects distant lands between which, except by sea, no communication would be possible, whereas the atmosphere is not such an indispensable highway. Secondly, navigation on the Open Sea comprises no danger whatever to the security of the different States and the lives and property of their inhabitants, whereas aviation threatens such danger to a great extent. The chief question at issue is, therefore, whether the territorial State should or should not be considered to exercise sovereignty over the space of the atmosphere to an unbounded height, and to have the power to prevent the passage of foreign aviators altogether, or to enact stringent rules with which they have to comply. It would probably be best for the States in conference to adopt such rules concerning the whole space of the atmosphere as are similar to those valid by customary International Law for the maritime belt, that is:—to recognise, on the one hand, sovereignty of the territorial State over the space of its atmosphere, but, on the other hand, to give a right to foreign States to demand from the territorial State that foreign private—but not public!—air-vessels may pass through its atmosphere, provided they comply with the rules enacted by the territorial State for the aerial traffic.[293]
[292] The literature on aviation is abundant, see Holtzendorff, II. p. 230; Lawrence, § 73; Bonfils, Nos. 5311-5319; Despagnet, Nos. 433 bis and 433 ter; Mérignhac, II. pp. 398-410; Nys, I. pp. 523-532; Grünwald, "Das Luftschiff, &c." (1908); Meili, "Das Luftschiff, &c." (1908); Meurer, "Luftschiffahrtsrecht" (1909); Meyer, "Die Erschliessung des Luftraums und ihre rechtlichen Folgen" (1909); Magnani, "Il diritto sullo spazio aereo e l'aeronautica" (1909); Leech, "The Jurisprudence of the Air" (1910), a reprint from the Journal of the Royal Artillery, vol. XXXVII.; Lycklama à Nijeholt, "Air Sovereignty" (1910); Hazeltine, "The Law of the Air" (1911); Bielenberg, "Die Freiheit des Luftraums" (1911); Catellani, "Il diritto aereo" (1911); Sperl, "Die Luftschiffahrt, &c." (1911); Loubeyre, "Les principes du droit aérien" (1911); Fauchille in Annuaire, XIX. (1902) pp. 19-114, XXIV. (1911), and in R.G. VIII. (1901), pp. 414-485, XVII. (1910), pp. 55-62; Zitelmann in the Zeitschrift für internationales Privat- und Öffentliches Recht, XIX. (1909), pp. 458-496; Baldwin and Kuhm in A.J. IV. (1910), pp. 95-108, 109-132; Baldwin in Z.V. V. (1911), pp. 394-399.
[293] The Institute of International Law is studying the question of aviation, and passed, in 1911, at its meeting in Madrid, some rules concerning the "Régime juridiques des Aéronefs"; see Annuaire, XXIV. (1911).
Aviation through the atmosphere above the Open Sea will require special regulation on account of the dangers to the vessels of all nations traversing the sea, as will also aviation in general in time of war.
Inalienability of Parts of Territory.
§ 175. It should be mentioned that not every part of territory is alienable by the owner-State. For it is evident that the territorial waters are as much inseparable appurtenances of the land as are the territorial subsoil and atmosphere. Only pieces of land together with the appurtenant territorial waters are alienable parts of territory.[294] There is, however, one exception to this, since boundary waters[295] may wholly belong to one of the riparian States, and may therefore be transferred through cession from one to the other riparian State without the bank itself. But it is obvious that this is only an apparent, not a real, exception to the rule that territorial waters are inseparable appurtenances of the land. For boundary waters that are ceded to the other riparian State remain an appurtenance of land, although they are now an appurtenance of the one bank only.