THE INTERNATIONAL LAW OF AERIAL SPACE.

I. THE LAW OF AERIAL SPACE IN TIME OF PEACE.

The invention of wireless telegraphy and recent improvements in the aeroplane and dirigible balloons have greatly extended the possibilities of international aerial communication and navigation, and have thus rendered necessary a discussion of the law of the so-called aerial domain in works on international law.

During its session at Ghent in 1906, the Institute of International Law adopted the following principles: "The air is free. In time of peace and in time of war, states have over it only the rights necessary for their self-preservation." 1 These principles, which were based upon the views of Fauchille2 and accepted by a vote of 14 against 9, have been justly criticized. They are not in agreement

1 Article 1 of the regulations adopted by the Institute of International Law for Aerostats and Wireless Telegraphy, 21 Annuaire, 327-29. Cf. Art. 3 of the rules adopted at Madrid in 1911 which states that "aerial circulation is free" saving the rights of the underlying states to take certain measures to ensure security. 24 Annuaire, 346. The rules adopted in 1911 have no great importance. The following is the text of the remaining articles adopted at Ghent, in so far as they relate to the law of peace.

Art. 2. In default of special arrangements, the rules applicable to ordinary telegraphic communication are applicable to communication by wireless telegraphy.

Art. 3. Each state has the power (faculté), to the degree necessary for its security, to oppose, above its territory and its territorial waters, and to as great a height as it may find useful, the passage of Hertzian waves, whether these be emitted by apparatus belonging to the state or by private apparatus placed upon the earth, on board a vessel, or in a balloon.

Art. 4. In case of the prohibition of communication by wireless telegraphy, the government should at once notify the other governments of the prohibition it has made.

2 For the extremely interesting and suggestive views of M. Fauchille, the brilliant and versatile editor of the Revue Générale de Droit Int. Public, see Bonfils (Fauchille) Nos. 531, 1-10; Le domain aérien in 8 R. D. I. P. (1901), 414-490; Rapports a l'Institut de Droit Int. in 19 and 21 Annuaire, 19-86 and 76–87;. 17 R. D. I. P. (1910), 55 ff.; and 24 Annuaire, 23–126.

with recent articles and monographs 3 on this subject, and do not answer the practical necessities either of aerial navigation or wireless telegraphy, especially in time of war.

The correct principles were undoubtedly those formulated by Professor Westlake who proposed the following alternative article at the above-named session of the Institute: "The state has a right of sovereignty over the aerial space above its soil, saving a right of inoffensive passage (usage) for balloons and other aerial machines and for communication by wireless telegraphy."

From the standpoint of state or municipal law there can be little, if any, doubt that the aerial space is subject to the territorial sovereignty of the state underneath, at least as far as it can be utilized or controlled.

Justinian tells us that the air, like the high seas, is by natural right common to all. In the sense that all can breathe it in as they have opportunity this is certainly true; but it can hardly be accepted as a proposition of jurisprudence with respect to its use for the support of a vehicle of transportation."

There existed, however, another principle of the Civil Law which declared that the lord of the soil was also lord of the heavens (dominus soli; dominus coeli) which, with certain limitations and

3 See especially Judge Baldwin and Arthur Kuhn in 4 this JOURNAL (1910), 94 ff. and 109 ff.; Grünwald, Das Luftschiff, etc. (1908); Julliot, De la proprieté du domain aérien (1909); Meurer, Luftschiffahrtsrecht (1909); Meyer, Die Erschliessung des Luftraumes in ihrem rechtlichen Folgen (1909); Schneeli, Radiotelegraphie und Völkerrecht (1908); Fleischmann, Grundgedank eines Luftrechts (1910); and Wilson in 5 Am. Pol. Sci. Rev. (1911), 171 ff.

4 See 21 Annuaire (1906), 297-99. Westlake's article received but three votes at the time of its proposal (1906) to the Institute, but it has since won wide support. Nearly all of the above named authorities are in substantial accord with its provisions.

5 Judge Baldwin in 4 this JOURNAL (1910), 95. He cites Inst. I, 1 de rerum divisione, § 1; and Dig. I, 8, de divisione rerum, § 2, 1.

6 Julliot, op. cit., p. 7, The Roman tradition of ownership in the aerial space was revived in the later Middle Ages and came down to Blackstone through Coke upon Littleton. Blackstone says: "Land hath also, in its legal signification, an indefinite extent upwards as well as downwards. Cujus est solum ejus est usque ad coelum is the maxim of the law So that the word 'land' includes not only the face of the earth, but everything under it, or over it." Cooley's Blackstone (4th ed.), Bk. II, p. 18. Cf. Coke upon Littleton (Thomas' ed., 1836), Bk. II. ch. 1.

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modifications, appears to have been incorporated into our common law."

war.

Control of the aerial space by the territorial power underneath is necessary for various purposes in time of peace as well as in time of As far as the use of wireless telegraphy is concerned, it is necessary in order to oppose the passage of Hertzian waves to the degree that the security or interests of the state may demand. In respect to aerial navigation, it may be desirable or necessary in order to prevent espionage, to enforce the collection of customs duties, maintain sanitary and quarantine regulations, and prevent various crimes, particularly smuggling.

From the standpoint of international law, it would seem that the state underneath has a limited right of territorial sovereignty or jurisdiction over the aerial space above, at least as far as it can be utilized or controlled. The aerial space above the ocean or unoccupied territory is of course free; but this can hardly be claimed in respect to that portion of the atmosphere above the territorial waters

7 It is expressly incorporated into the codes of Germany, France and Switzerland. For citation and discussion of cases bearing on the rights of the owner of the soil in the United States, see Judge Baldwin and Arthur Kuhn in 4 this JOURNAL (1910), 102 ff., and 123 ff. As far as the state is concerned, the theory of ownership has of course been abandoned for that of imperium or territorial sovereignty. Grünwald appears to stand alone in clinging to the theory of dominium or ownership.

For citations from the German, French, and Swiss codes, see 4 this JOURNAL (1910), 98 f., 127 f; Julliot, 7 f.; and Meurer, 13 ff.

8 Art. 3 of the rules of the Institute. See note, 1, supra.

Some publicists favor the division of the aerial space, for purposes of jurisdiction, into an upper and lower zone. Rolland (13 R. D. I. P., 58 ff.) holds the atmosphere to be territorial to a distance of 330 metres. Fauchille favors exclusive control for purposes of self-defense to a distance of 500 metres (17 R. D. I. P. 60).

A number of the older authorities favor the rule or principle of the cannon shot; but, since modern aeronautic cannon are said to have a vertical range of 5,500, 7,400, and even 11,500 metres, this would render freedom in the upper zone wholly illusory. Besides, the analogy between the marine league or range of cannon shot as applied to the ocean and aerial space soon breaks down. In the case of the ocean, the reasons for control decrease in proportion to the distance from the shore; in the case of aerial space, the danger (as, e. g., from the weight of falling bodies) may increase in proportion to the distance from the earth's surface.

(including the marginal seas) or above that part of the land surface which is inhabited by peoples organized into political communities.

The nature of this control appears to be analogous to that exercised over a state's territorial waters, more particularly the marginal seas, straits, and international rivers. Foreign airships should be granted a right of innocent or inoffensive passage; and, in general, the same rules must be applicable to them in the territorial atmosphere as are applied to foreign vessels in territorial waters. Their nationality will doubtless be determined by their flag or registry, and though in principle subject to the jurisdiction of the state above whose territory they pass, they will be practically exempt from its criminal jurisdiction except in respect to crimes which affect the interests or disturb the peace of its inhabitants.10

II. THE LAW OF AERIAL SPACE IN TIME OF WAR.

Very few positive rules or principles of international law applicable to aerial warfare have been thus far developed. The rules are largely inferential and speculative in their character, and are based upon generally recognized principles or analogous practices in land or naval warfare.

Many of the states represented at the Second Hague Peace Conference of 1907 agreed to "prohibit, for a period extending to the close of the Third Peace Conference, the discharge of projectiles and explosives from balloons or by other new methods of a similar nature." 11 But this "Declaration" was only signed by twentyseven states, and the signatories did not include four of the great maritime Powers.12 It cannot, therefore, be regarded as an integral part of international law.

10 This would at least be the case with private airships. Public airships will probably enjoy the rights and privileges of so-called exterritoriality as in the case of public vessels or warships.

111 H. D. (Hague Declaration) (1907); Higgins, The Hague Peace Conferences, 485-91. See select bibliography on p. 488.

12 Viz: Germany, Italy, Russia and Japan. The remaining non-signatory Powers were Chili, Denmark, Spain, Guatemala, Mexico, Montenegro, Nicaragua (which has since adhered), Paraguay, Roumania, Servia, Sweden, and Venezuela.

The only conventional rule of international law of great importance bearing on the subject of aerial warfare is found in the Hague Regulations respecting the Laws and Customs of War on Land:

The attack or bombardment, by any means whatever, of towns, villages, habitations, or buildings which are not defended is forbidden (Art. 25).13

But the following rules bearing upon aerial warfare are also based on convention, though they are of minor importance:

Belligerents are also forbidden:

(a) To erect on the territory of a neutral Power a wireless telegraphy station, or any apparatus intended to serve as a means of communication with belligerent forces on land or sea;

(b) To use any installation of this kind established by them before the war on the territory of the neutral Power for purely military purposes, and which has not been opened for the service of public messages. 14

A neutral Power is not bound to forbid or restrict, on behalf of belligerents, the use of telegraphic or telephonic cables or of wireless telegraphy apparatus, whether belonging to it or to companies or private individuals.15

It should be noted that Great Britain and the United States were among the signatories. Only 13 states had ratified or adhered to this Declaration by July, 1911.

13 H. R. (1907), Art. 25.

14 5 H. C. (1907), Art. 3. This article was suggested by the experiences of the Russo-Japanese War when the Russians erected a receiving station at Che-foo in China for the purpose of communicating with Port Arthur by means of wireless telegraphy. See Hershey, 122, 124, 266-67; Higgins, 282 f; and Lawrence, War and Neutrality in the Far East (2d ed.), 218-20.

Art. 5 of 5 H. C. also makes it obligatory upon neutrals not to permit such acts on its territory. According to 13 H. C. (1907), 5, belligerents are particularly forbidden to "erect wireless telegraphy stations, etc.," in neutral ports or waters.

15 5 H. C., Art. 8. Article 9 adds:

'Every restrictive or prohibitive measure taken by a neutral Power in regard to the matters referred to in Articles 7 and 8 must be applied impartially by it to the belligerents.

"The neutral Power shall see to it that the same obligation is observed by companies or private owners of telegraph or telephone cables or of wireless telegraphy apparatus."