§ 521. As treaties are binding upon the contracting States, changes in the government or even in the form of government of one of the parties can as a rule have no influence whatever upon the binding force of treaties. Thus, for instance, a treaty of alliance concluded by a State with constitutional government remains valid, although the Ministry may change. And no head of a State can shirk the obligations of a treaty concluded by his State under the government of his predecessor. Even when a monarchy turns into a republic, or vice versa, treaty obligations regularly remain the same. For all such changes and alterations, important as they may be, do not alter the person of the State which concluded the treaty. If, however, a treaty stipulation essentially presupposes a certain form of government, then a change from such form makes such stipulation void, because its execution has become impossible.[887]

§ 522. According to the principle pacta tertiis nec nocent nec prosunt, a treaty concerns the contracting States only; neither rights nor duties, as a rule, arise under a treaty for third States which are not parties to the treaty. But sometimes treaties have indeed an effect upon third States. Such an effect is always produced when a treaty touches previous treaty rights of third States. Thus, for instance, a commercial treaty conceding more favourable conditions than hitherto have been conceded by the parties thereto has an effect upon all such third States as have previously concluded commercial treaties containing the so-called most-favoured-nation clause[888] with one of the contracting parties.

The question arises whether in exceptional cases third States can acquire rights under such treaties as were specially concluded for the purpose of creating such rights not only for the contracting parties but also for third States. Thus, the Hay-Pauncefote Treaty between Great Britain and the United States of 1901, and the Hay-Varilla Treaty between the United States and Panama of 1903, stipulate that the Panama Canal to be built shall be open to vessels of commerce and of war of all nations, although Great Britain, the United States, and Panama only are parties.[889] Thus, further, article 5 of the Boundary Treaty of Buenos Ayres of September 15, 1881, stipulates that the Straits of Magellan shall be open to vessels of all nations, although Argentina and Chili only are parties. Again, the Treaty of Paris, signed on March 30, 1856, and annexed to the Peace Treaty of Paris of 1856, stipulates that Russia shall not fortify the Aland[890] Islands; although this stipulation was made in the interest of Sweden, only Great Britain, France, and Russia are parties. I believe that the question must be answered in the negative, and nothing prevents the contracting parties from altering such a treaty without the consent of third States, provided the latter have not in the meantime acquired such rights through the unanimous tacit consent of all concerned.

It must be emphasised that a treaty between two States can never invalidate a stipulation previously created by a treaty between one of the contracting parties and a third State, unless the latter expressly consents. If, for instance, two States have entered into an alliance and one of them afterwards concludes a treaty with a third State, according to which all conflicts without exception shall be settled by arbitration, the previous treaty of alliance remains valid even in the case of war breaking out between the third State and the other party to the alliance.[891] Therefore, when in 1911 Great Britain contemplated entering, with the United States of America, into a treaty of general arbitration according to which all differences should be decided by arbitration, she notified Japan of her intention, on account of the existing treaty of alliance, and Japan consented to substitute for the old treaty a new treaty of alliance,[892] article 4 of which stipulates that the alliance shall never concern a war with a third Power with whom one of the allies may have concluded a treaty of general arbitration.

VII MEANS OF SECURING PERFORMANCE OF TREATIES

Vattel, II. §§ 235-261—Hall, § 115—Lawrence, § 134—Phillimore, II. §§ 54-63A—Bluntschli, §§ 425-441—Heffter, §§ 96-99—Geffcken in Holtzendorff, III. pp. 85-90—Ullmann, § 83—Bonfils, Nos. 838-844—Despagnet, Nos. 451-452—Pradier-Fodéré, II. Nos. 1156-1169—Rivier, II. pp. 94-97—Nys, III. pp. 36-41—Calvo, III. §§ 1638-1642—Fiore, II. Nos. 1018-1019, and Code, Nos. 784-791—Martens, I. § 115—Nippold, op. cit. pp. 212-227.

§ 523. As there is no international institution which could enforce the performance of treaties, and as history teaches that treaties have frequently been broken, various means of securing performance of treaties have been made use of. The more important of these means are oaths, hostages, pledges, occupation of territory, guarantee. Nowadays these means, which are for the most part obsolete, have no longer great importance on account of the gratifying fact that all States are now much more conscientious and faithful as regards their treaty obligations than in former times.

§ 524. Oaths are a very old means of securing the performance of treaties, which was constantly made use of not only in antiquity and the Middle Ages, but also in modern times. For in the sixteenth and seventeenth centuries all important treaties were still secured by oaths. During the eighteenth century, however, the custom of securing treaties by oaths gradually died out, the last example being the treaty of alliance between France and Switzerland in 1777, which was solemnly confirmed by the oaths of both parties in the Cathedral at Solothurn. The employment of oaths for securing treaties was of great value in the times of absolutism, when little difference used to be made between the State and its monarch. The more the distinction grew into existence between the State as the subject of International Law on the one hand, and the monarch as the temporary chief organ of the State on the other hand, the more such oaths fell into disuse. For an oath can exercise its force on the individual only who takes it, and not on the State for which it is taken.

§ 525. Hostages are as old a means of securing treaties as oaths, but they have likewise, for ordinary purposes[893] at least, become obsolete, because they have practically no value at all. The last case of a treaty secured by hostages is the Peace of Aix-la-Chapelle in 1748, in which hostages were stipulated to be sent by England to France for the purpose of securing the restitution of Cape Breton Island to the latter. The hostages sent were Lords Sussex and Cathcart, who remained in France till July 1749.

§ 526. The pledging of movable property by one of the contracting parties to the other for the purpose of securing the performance of a treaty is possible, but has not frequently occurred. Thus, Poland is said to have pledged her crown jewels once to Prussia.[894] The pledging of movables is nowadays quite obsolete, although it might on occasion be revived.

§ 527. Occupation of territory, such as a fort or even a whole province, as a means of securing the performance of a treaty, has frequently been made use of with regard to the payment of large sums of money due to a State under a treaty. Nowadays such occupation is only resorted to in connection with treaties of peace stipulating the payment of a war indemnity. Thus, the preliminary peace treaty of Versailles in 1871 stipulated that Germany should have the right to keep certain parts of France under military occupation until the final payment of the war indemnity of five milliards of francs.

§ 528. The best means of securing treaties, and one which is still in use generally, is the guarantee of such other States as are not directly affected by the treaty. Such guarantee is a kind of accession[895] to the guaranteed treaty, and a treaty in itself—namely, the promise of the guarantor eventually to do what is in his power to compel the contracting party or parties to execute the treaty.[896] Guarantee of a treaty is a species only of guarantee in general, which will be discussed below, §§ 574-576a.

VIII PARTICIPATION OF THIRD STATES IN TREATIES

Hall, § 114—Wheaton, § 288—Hartmann, § 51—Heffter, § 88—Ullmann, § 81—Bonfils, Nos. 832-834—Despagnet, No. 448—Pradier-Fodéré, II. Nos. 1127-1150—Rivier, II. pp. 89-93—Calvo, III. §§ 1621-1626—Fiore, II. Nos. 1025-1031—Martens, I. § 111.

§ 529. Ordinarily a treaty creates rights and duties between the contracting parties exclusively. Nevertheless, third States may be interested in such treaties, for the common interests of the members of the Family of Nations are so interlaced that few treaties between single members can be concluded in which third States have not some kind of interest. But such interest, all-important as it may be, must not be confounded with participation of third States in treaties. Such participation can occur in five different forms—namely, good offices, mediation, intervention, accession, and adhesion.[897]

§ 530. A treaty may be concluded with the help of the good offices or through the mediation of a third State, whether these offices be asked for by the contracting parties or be exercised spontaneously by a third State. Such third State, however, does not necessarily, either through good offices or through mediation, become a real party to the treaty, although this might be the case. A great many of the most important treaties owe their existence to the good offices or mediation of third Powers. The difference between good offices and mediation will be discussed below, vol. II. § 9.

§ 531. A third State may participate in a treaty in such a way that it interposes dictatorially between two States negotiating a treaty and requests them to drop or to insert certain stipulations. Such intervention does not necessarily make the interfering State a real party to the treaty. Instances of threatened intervention of such a kind are the protest on the part of Great Britain against the preliminary peace treaty concluded in 1878 at San Stefano[898] between Russia and Turkey, and that on the part of Russia, Germany, and France in 1895 against the peace treaty of Shimonoseki[899] between Japan and China.

§ 532. Of accession there are two kinds. Accession means, firstly, the formal entrance of a third State into an existing treaty so that such State becomes a party to the treaty with all rights and duties arising therefrom. Such accession can take place only with the consent of the original contracting parties, and accession always constitutes a treaty of itself. Very often the contracting parties stipulate expressly that the treaty shall be open to the accession of a certain State. And the so-called law-making treaties, as the Declaration of Paris or the Geneva Convention for example, regularly stipulate the option of accession of all such States as have not been originally contracting parties.

But there is, secondly, another kind of accession possible. For a State may enter into a treaty between other States for the purpose of guarantee.[900] This kind of accession makes the acceding State also a party to the treaty; but the rights and duties of the acceding State are different from the rights and duties of the other parties, for the former is a guarantor only, whereas the latter are directly affected by the treaty.

§ 533. Adhesion is defined as such entrance of a third State into an existing treaty as takes place either with regard only to a part of the stipulations or with regard only to certain principles laid down in the treaty. Whereas through accession a third State becomes a party to the treaty with all the rights and duties arising from it, through adhesion a third State becomes a party only to such parts or principles of the treaty as it has adhered to. But it must be specially observed that the distinction between accession and adhesion is one made in theory, to which practice frequently does not correspond. Often treaties speak of accession of third States where in fact adhesion only is meant, and vice versa. Thus, article 6 of the Hague Convention with respect to the laws and customs of war on land stipulates the possibility of future adhesion of non-signatory Powers, although accession is meant.

IX EXPIRATION AND DISSOLUTION OF TREATIES

Vattel, II. §§ 198-205—Hall, § 116—Westlake, I. pp. 284-286—Lawrence, § 134—Halleck, I. pp. 293-296—Taylor, §§ 394-399—Wharton, II. § 137A—Wheaton, § 275—Moore, V. §§ 770-778—Bluntschli, §§ 450-461—Heffter, § 99—Ullmann, § 85—Bonfils, Nos. 855-860—Despagnet, Nos. 453-455—Pradier-Fodéré, II. Nos. 1200-1218—Mérignhac, II. p. 788—Rivier, II. § 55—Nys, III. pp. 48-53—Calvo, III. §§ 1662-1668—Fiore, II. Nos. 1047-1052—Martens, I. § 117—Jellinek, "Die rechtliche Natur der Staatenverträge" (1880), pp. 62-64—Nippold, op. cit. pp. 235-248—Olivi, "Sull' estinzione dei trattati internazionali" (1883)—Schmidt, "Ueber die völkerrechtliche clausula rebus sic stantibus, &c." (1907)—Kaufmann, "Das Wesen des Völkerrechts und die clausula rebus sic stantibus" (1911)—Bonucci in Z.V. IV. (1910), pp. 449-471.

§ 534. The binding force of treaties may terminate in four different ways, because a treaty may either expire, or be dissolved, or become void, or be cancelled.[901] The grounds of expiration of treaties are, first, expiration of the time for which a treaty was concluded, and, secondly, occurrence of a resolutive condition. Of grounds of dissolution of treaties there are three—namely, mutual consent, withdrawal by notice, and vital change of circumstances. In contradistinction to expiration and dissolution as well as to voidance and cancellation, performance of treaties does not terminate their binding force. A treaty whose obligation has been performed is as valid as before, although it is now of historical interest only.

§ 535. All such treaties as are concluded for a certain period of time only, expire with the expiration of such time, unless they are renewed or prolonged for another period. Such time-expiring treaties are frequently concluded, and no notice is necessary for their expirations, except when specially stipulated.

A treaty, however, may be concluded for a certain period of time only, but with the additional stipulation that the treaty shall after the lapse of such period be valid for another such period, unless one of the contracting parties gives notice in due time.

§ 536. Different from time-expiring treaties are such as are concluded under a resolutive condition, which means under the condition that they shall at once expire with the occurrence of certain circumstances. As soon as these circumstances arise, the treaties expire.

§ 537. A treaty, although concluded for ever or for a period of time which has not yet expired, may nevertheless always be dissolved by mutual consent of the contracting parties. Such mutual consent can become apparent in three different ways.

First, the parties can expressly and purposely declare that a treaty shall be dissolved; this is rescission. Or, secondly, they can conclude a new treaty concerning the same objects as those of a former treaty without any reference to the latter, although the two treaties are inconsistent with each other. This is substitution, and in such a case it is obvious that the treaty previously concluded was dissolved by tacit mutual consent. Or, thirdly, if the treaty is such as imposes obligations upon one of the contracting parties only, the other party can renounce its rights. Dissolution by renunciation is a case of dissolution by mutual consent, since acceptance of the renunciation is necessary.

§ 538. Treaties, provided they are not such as are concluded for ever, may also be dissolved by withdrawal, after notice by one of the parties. Many treaties stipulate expressly the possibility of such withdrawal, and as a rule contain details in regard to form and period in which notice is to be given for the purpose of withdrawal. But there are other treaties which, although they do not expressly stipulate the possibility of withdrawal, can nevertheless be dissolved after notice by one of the contracting parties. To that class belong all such treaties as are either not expressly concluded for ever or apparently not intended to set up an everlasting condition of things. Thus, for instance, a commercial treaty or a treaty of alliance not concluded for a fixed period only can always be dissolved after notice, although such notice be not expressly stipulated. Treaties, however, which are apparently intended, or expressly concluded, for the purpose of setting up an everlasting condition of things, and, further, treaties concluded for a certain period of time only, are as a rule not notifiable, although they can be dissolved by mutual consent of the contracting parties.

It must be emphasised that all treaties of peace and all boundary treaties belong to this class. It cannot be denied that history records many cases in which treaties of peace have not established an everlasting condition of things, since one or both of the contracting States took up arms again as soon as they recovered from the exhausting effect of the previous war. But this does not prove either that such treaties can be dissolved through giving notice, or that, at any rate as far as International Law is concerned, they are not intended to create an everlasting condition of things.

§ 539. Although, as just stated, treaties concluded for a certain period of time, and such treaties as are apparently intended or expressly contracted for the purpose of setting up an everlasting condition of things, cannot in principle be dissolved by withdrawal of one of the parties, there is an exception to this rule. For it is an almost universally recognised fact that vital changes of circumstances may be of such a kind as to justify a party in notifying an unnotifiable treaty. The vast majority of publicists, as well as all the Governments of the members of the Family of Nations, defend the principle Conventio omnis intelligitur rebus sic stantibus, and they agree,[902] therefore, that all treaties are concluded under the tacit condition rebus sic stantibus. That this condition involves a certain amount of danger cannot be denied, for it can be, and indeed sometimes has been, abused for the purpose of hiding the violation of treaties behind the shield of law, and of covering shameful wrong with the mantle of righteousness. But all this cannot alter the fact that this exceptional condition is as necessary for International law and international intercourse as the very rule pacta sunt servanda. When, for example, the existence or the necessary development of a State stands in unavoidable conflict with such State's treaty obligations, the latter must give way, for self-preservation and development in accordance with the growth and the necessary requirements of the nation are the primary duties of every State. No State would consent to any such treaty as would hinder it in the fulfilment of these primary duties. The consent of a State to a treaty presupposes a conviction that such treaty is not fraught with danger to its existence and development, and implies a condition that, if by an unforeseen change of circumstances the obligations stipulated in the treaty should imperil the said State's existence and necessary development, the treaty, although by its nature unnotifiable, should nevertheless be notifiable.

The danger of the clause rebus sic stantibus is to be found in the elastic meaning of the term "vital changes of circumstances," as, after all, a State must in every special case judge for itself whether or no there is a vital change of circumstances justifying its withdrawal from an unnotifiable treaty. On the other hand, the danger is counterbalanced by the fact that the frequent and unjustifiable use of the clause rebus sic stantibus by a State would certainly destroy all its credit among the nations.

Be that as it may, it is generally agreed that certainly not every change of circumstances justifies a State in making use of the clause. All agree that, although treaty obligations may through a change of circumstances become disagreeable, burdensome, and onerous, they must nevertheless be discharged. All agree, further, that a change of government and even a change in the form of a State, such as the turning of a monarchy into a republic and vice versa, does not alone and in itself justify a State in notifying such a treaty as is by its nature unnotifiable. On the other hand, all agree in regard to many cases in which the clause rebus sic stantibus could justly be made use of. Thus, for example, if a State enters into a treaty of alliance for a certain period of time, and if before the expiration of the alliance a change of circumstances occurs, so that now the alliance endangers the very existence of one of the contracting parties, all will agree that the clause rebus sic stantibus would justify such party in notifying the treaty of alliance.

A certain amount of disagreement as to the cases in which the clause might or might not be justly applied will of course always remain. But the fact is remarkable that during the nineteenth century not many cases of the application of the clause have occurred. And the States and public opinion everywhere have come to the conviction that the clause rebus sic stantibus ought not to give the right to a State at once to liberate itself from the obligations of a treaty, but only the claim to be released from these obligations by the other parties to the treaty. Accordingly, when a State is of the opinion that the obligations of a treaty have through a vital change of circumstances become unbearable, it should first approach the other party or parties and request them to abrogate the treaty. And it is only when such abrogation is refused that a State may perhaps be justified in declaring that it could no longer consider itself bound by the obligations concerned. Thus, when, in 1870, during the Franco-German War, Russia declared her withdrawal from such stipulations of the Treaty of Paris of 1856 as concerned the neutralisation of the Black Sea and the restriction imposed upon Russia in regard to men-of-war in that sea, Great Britain protested, and a conference was held in London in 1871. Although by a treaty signed on March 13, 1871, this conference, consisting of the signatory Powers of the Treaty of Paris—namely, Austria, England, France, Germany, Italy, Russia, and Turkey—complied with the wishes of Russia and abolished the neutralisation of the Black Sea, it adopted in a protocol[903] of January 17, 1871, the following declaration:—"Que c'est un principe essentiel du droit des gens qu'aucune Puissance ne peut se délier des engagements d'un traité, ni en modifier les stipulations, qu'à la suite de l'assentiment des parties contractantes, au moyen d'une entente amicale."

In spite of this declaration, signed also by herself, Russia in 1886 notified her withdrawal from article 59 of the Treaty of Berlin of 1878 stipulating the freedom of the port of Batoum.[904] The signatory Powers of the Treaty of Berlin seem to have tacitly consented, with the exception of Great Britain, which protested. Again, in October 1908, Austria-Hungary, in defiance of article 25 of the Treaty of Berlin, 1878, proclaimed her sovereignty over Bosnia and Herzegovina, which hitherto had been under her occupation and administration, and simultaneously Bulgaria, in defiance of article 1 of the same treaty, declared herself independent.[905] Thus the standard value of the Declaration of the Conference of London of 1871 has become doubtful again.

X VOIDANCE OF TREATIES

See the literature quoted at the commencement of § 534.

§ 540. A treaty, although it has neither expired nor been dissolved, may nevertheless lose its binding force by becoming void.[906] And such voidance may have different grounds—namely, extinction of one of the two contracting parties, impossibility of execution, realisation of the purpose of the treaty otherwise than by fulfilment, and, lastly, extinction of such object as was concerned in a treaty.

§ 541. All treaties concluded between two States become void through the extinction of one of the contracting parties, provided they do not devolve upon such State as succeeds to the extinct State. That some treaties devolve upon the successor has been shown above (§ 82), but many treaties do not. On this ground all political treaties, such as treaties of alliance, guarantee, neutrality, and the like, become void.

§ 542. All treaties whose execution becomes impossible subsequent to their conclusion are thus rendered void. A frequently quoted example is that of three States concluding a treaty of alliance and subsequent war breaking out between two of the contracting parties. In such case it is impossible for the third party to execute the treaty, and it becomes void.[907] It must, however, be added that the impossibility of execution may be temporary only, and that then the treaty is not void but merely suspended.

§ 543. All treaties whose purpose is realised otherwise than by fulfilment become void. For example, a treaty concluded by two States for the purpose of inducing a third State to undertake a certain obligation becomes void if the third State voluntarily undertakes the same obligation before the two contracting States have had an opportunity of approaching the third State with regard to the matter.

§ 544. All treaties whose obligations concern a certain object become void through the extinction of such object. Treaties, for example, concluded in regard to a certain island become void when such island disappears through the operation of nature, as likewise do treaties concerning a third State when such State merges in another.

XI CANCELLATION OF TREATIES

See the literature quoted at the commencement of § 534.