3. Treaty Obligation from the Protestant Reformation to 1919: Part 3 The Treaty Not Part of International Law

Allen Z. Hertz was senior advisor in the Privy Council Office serving Canada's Prime Minister and the federal cabinet. He formerly worked in Canada's Foreign Affairs Department and earlier taught history and law at universities in New York, Montreal, Toronto and Hong Kong. He studied European history and languages at McGill University (B.A.) and then East European and Ottoman history at Columbia University (M.A., Ph.D.). He also has international law degrees from Cambridge University (LL.B.) and the University of Toronto (LL.M.).

Foreword

This is first publication of the integral text of "Treaty Obligation from the Protestant Reformation to 1919." However, portions dealing with "Honour's Role in the International States' System" were published in Denver Journal of International Law and Policy, Vol. 31 (2002), pp. 113-155, and also appear as a separate posting on this website. Research for this present essay took place in Ottawa during service with the Privy Council Office which greatly assisted by regularly making conveniently available a variety of materials, including some rare books, from the Supreme Court of Canada Library, the National Library of Canada and the Library of Parliament. "Treaty Obligation from the Protestant Reformation to 1919" is current to the end of 2002.

The Part 1: Introduction discusses the thesis that before the First World War the moral and "natural law" principle that "agreements are to be kept" (pacta sunt servanda) was binding in honour alone. Part 2 reviews classical international law’s assessment of the treaty as a legal source. In this present posting, Part 3 shows that, before the First World War, treaties were not always accepted as an integral part of international law.  Part 4 explains why treaties were then not seen as legally binding, and describes how international law governed treaties via pacta sunt servanda as a moral and "natural law"requirement.  Part 5 illuminates the State’s moral personality with reference to both personification and treaties as “contracts of kings.” Honour is identified as one of the principal features of pre-1914 European civilization and international relations in Part 6.  Part 7 portrays the “old diplomacy” as a milieu focusing on honour.  Part 8 shows what kings, prime ministers, philosophers and lawyers had to say about treaties binding in honour. The honour of treaties as seen in Britain and the USA is the subject of Parts 9 and 10 respectively.  Part 11 recalls that, before 1914, all treaties were a “gentlemen’s agreement” -- an expression which only made sense in public international law after 1919, i.e. as a specific exception to the new rule that treaties are normally binding in law. Part 12 treats the “new diplomacy” that arose during the First World War and discusses the rise of the legal paradigm.  Finally, Part 13 highlights the law-centered order inaugurated by the 1919 Paris Peace Settlement which created conditions supporting 20th-century discourse about treaties as legally binding.  

The treaty not part of international law

French prelate and writer François Fénelon (1651-1715) spoke about international law and “the inviolable faith of peace treaties” as if they were two categories, separate in some unspecified way.^[1]  Inner Temple barrister Robert Plumer Ward (1765-1846) was aware of this characteristic distinction.  He questioned “how far the particular rights conferred or taken away by Treaty, are the result of the Law of Nations” and concluded:

That law permits us to agree upon certain points by Treaty, which points, when agreed upon, become legal by that Treaty, and not by a general Law of Nations; so that accurately speaking, all that the latter amounts to... is the one general proposition, that we may determine upon certain things by agreement.^[2]  

More to the point, Lorimer asked whether treaties are properly speaking part of international law.^[3]  This is a significant question because a large body of evidence suggests that into the 20^th century, the treaty per se tended to be excluded from the ambit of international law, then more commonly identified with customary law.^[4]  This fine point can be appreciated by looking at some 19th-century references to contraventions of customary law, where the issue is one of “legality” or “illegality,” as opposed to examples of breach of treaty, where violation of international law is significantly not alleged.  Relevant too are many of the pre-1914 arbitration treaties, the 1919 League of Nations Covenant and the 1920 World Court Statute, all of which reflect something of the historic dichotomy between “treaties” and “international law.”^[5]

Custom: Lawler’s case

In 1860, the British law officers gave Foreign Secretary Lord John Russell a legal opinion^[6] on the conduct of Nicholls, a British warder from Gibraltar, who had crossed over into Spain to apprehend Patrick Lawler, an escaped British convict.  Spain’s Minister protested to Russell that, without Spanish consent, Nicholls had first stupefied Lawler with drugs or alcohol and then put him aboard the ferry to Gibraltar.  Customary international law was then the source of the rule that a foreign State may not exercise criminal jurisdiction on another State’s territory.^[7]  Because the law officers judged Nicholls’ behaviour to be “a plain breach of international law,” they advised that Lawler be returned to Spain for release.^[8]

    

Custom: USA blockade of the Confederacy

During the American Civil War (1861-1865), French and British textile workers were idle because Confederate cotton could not pierce a USA naval blockade proclaimed by President Lincoln in April 1861.^[9]   Between the USA and Britain, the law of blockade was then almost entirely customary.^[10]  British Prime Minister Lord Palmerston described for Queen Victoria a House of Commons debate as to whether the USA blockade was “consistent with the law of nations” or “illegal” as a “violation of principles of international law.”^[11]  Discussing this “question of international law,” Foreign Secretary Russell assured Parliament that the USA blockade was “such as the law of nations recognizes.”^[12]  The British government was pleased with a law officers’ assessment that the USA blockade was legal because otherwise there would have been added public pressure for Britain to intervene on the Confederacy’s side.^[13]

Custom: 'The Trent'

During the American Civil War, Britain and the USA came perilously close to conflict due to a high seas incident perceived to be governed by customary international law.^[14]  On November 8, 1861, a USA warship stopped and boarded the British mail steamer Trent travelling from Cuba to England.  The Trent was carrying Confederate representatives who were seized and carried off to prison in the USA.  Admiralty counsel and the law officers gave Prime Minister Palmerston legal opinions which caused him to tell the Queen that the arrest was a “gross outrage and violation of international law.”^[15]  “An undoubted breach of international law” was the concurring view of Victoria who knew enough about the discipline to debate legal points with her ministers.^[16]  The Royal Navy off the USA coast, reinforcements for Canada, and France’s diplomatic support for Britain persuaded President Lincoln to free the Confederate captives who boarded a British warship near Cape Cod.^[17]

Custom: Russian soldiers in Ottoman Serbia

Queen Victoria prepared a memorandum about the Eastern question in 1876, when the Ottoman sultan was still de jure sovereign of Serbia.  Customary international law was then the source of the rule that, during peacetime, a foreign State and its officials may not interfere in the internal affairs of another country.^[18]  Accordingly, Victoria wrote:

The Panslavonian feeling in Russia... may make it impossible, or at least very difficult, for the [Russian] Emperor to prevent the influx of Russian officers and soldiers into Serbia, what we and Turkey have denounced as contrary to international law.^[19]

Treaty: end of the Cracow Republic

A February 1846 Polish insurrection led Austria, Prussia and Russia to extinguish the Cracow Republic — a “free city” under the 1815 Vienna Treaty.^[20]  Not having consented to this change, Britain and France denounced Cracow’s annexation to Austria as the first direct and open violation of the 1815 treaty.  However, the abundant diplomatic papers about the unilateral alteration of Cracow’s status are significantly without any allegation of breach of international law.^[21]  Rather, British Foreign Secretary Lord Palmerston took the Northern Powers to task for “a violation of positive stipulations contained in the General Treaty of Vienna” and stressed that “Her Majesty’s Government [is] deeply impressed with the conviction that it is above all things important that the engagements of Treaties should at all times be faithfully observed.”^[22]

With French public opinion favouring the Poles, Foreign Minister François Guizot “solemnly protested against the suppression of the Cracow Republic as an act positively contrary to the letter and spirit of the June 9, 1815 Vienna Treaty.”  Guizot instructed France’s Ambassador in Vienna to tell Austria’s Chancellor Prince Metternich:

After the long and redoubtable agitations which have so profoundly shaken Europe, it is upon respect for treaties and the rights which they consecrate that the European order is founded and maintained.  No power can free itself from them, without at the same time freeing the others.  France has never given an example of a similar injury to the policy of maintaining peace.  France has not forgotten the sad sacrifices imposed upon her by the 1815 treaties. She could therefore rejoice in an act which would authorize her — by just reciprocity — henceforth to consult only the calculation of her future interests.  However, now it is France who recalls to the faithful observation of these treaties the powers which have derived the greatest advantages from them. Now, it is France that is preoccupied above all with maintaining acquired rights and respecting the independence of States.^[23] 

 

Treaty: denunciation of the Black Sea clauses

The Black Sea was neutralized by the 1856 Paris Treaty ending the Crimean War.^[24]  The Russians felt humiliated that they lacked the right to maintain a Black Sea fleet or fortify their seacoast there.^[25]   Quickly reacting to the new political reality created by France’s stunning defeat in the Franco-Prussian War, Russian Foreign Minister Prince Alexander Gorchakov in October 1870 tried to repudiate unilaterally the Paris Treaty’s Black Sea clauses.  Referring to “the successive changes to which, during these last years, the transactions considered to be the foundation of Europe’s equilibrium have been subjected,” he sought to justify Russia’s denunciation:

The Treaty of 18/30 March 1856, moreover, has not escaped the derogations which have hit most of the European transactions, and in the presence of which, it would be difficult to affirm that the written law — founded on respect for Treaties as the basis of public law and the rule for relations between States — has maintained the same moral sanction which it was able to have in other times.^[26]

Rejecting Gorchakov’s reasoning, British Prime Minister William Gladstone sent Foreign Secretary Lord Granville a memorandum which, significantly, did not refer to a Russian violation of  international law:

We have here an allegation that certain facts have occurred which in the judgment of Russia are at variance with certain stipulations of the Treaty: and, the assumption is made that Russia, upon the strength of her own judgment as to the character of the facts, is entitled to release herself from certain other stipulations of that instrument.  The assumption is limited in its practical application to some of the provisions of the Treaty: but as every Treaty in point of obligation is one and indivisible, the assumption of a title to renounce any one of its terms is ipso facto an assumption of a title to renounce the whole.^[27]

Gladstone’s memorandum was the basis for the reply which Gorchakov received from Granville, who also failed to allege a violation of international law.^[28]   Such a charge was similarly absent from the Foreign Secretary’s otherwise strong comments to Queen Victoria:

The shell which Lord Granville has been led to expect, has burst, but in the most violent and illegitimate manner.  Perhaps if the thing was to be done, it is as well that the Russians have put themselves flagrantly in the wrong.  If they wish to succeed by negotiation, it obliges them to go back.  If they mean to make the attempt by the threat of brute force, they put against them whatever may remain of public opinion.  But if they succeed, it puts an end at once to the value of any treaty....   If they had come to Europe to ask for a revision, it would have been difficult to refuse to consider the merits of the question.  Russia’s present mode of proceeding is perfectly inadmissible.^[29]

Treaty: tripartite guarantee of Ottoman Empire

The 1856 Triple Treaty provides another example showing that failure to live up to treaty terms was understood as a “breach of faith” but not as a violation of international law.  Britain, France and Austria had promised to protect the “independence and integrity of the Ottoman Empire, sanctified by the Treaty of Paris.”^[30]  The Triple Treaty stipulated that any violation of the 1856 Paris Treaty would be a casus belli obliging the three powers to agree necessary measures with the Ottoman government and determine “among themselves without delay the use of their military and naval forces.”^[31]  The Triple Treaty was tested in April 1877, when Russia was about to attack the Ottoman Empire.  By then, the massacre of twelve thousand Christians in Ottoman Bulgaria had so stirred British public opinion that fighting Russia for the Turks was politically impossible.^[32]  Among other excuses, Foreign Secretary Lord Derby pleaded the doctrine of changed circumstances, rebus sic stantibus:

No Treaties can be or are intended to be eternal. They are framed with reference to existing circumstances, and though I do not say whether that is so or is not the case with regard to the Treaty of 1856, yet nothing has been more common in European diplomacy than the recognition of the fact that Treaties do by the lapse of time and the force of events become obsolete.  I do not think that it would be a fair or satisfactory conclusion to come to either that you must be eternally bound by a Treaty, made long ago under conditions wholly different from those now existing, or that you are to be held guilty of a breach of faith because you consider it to be no longer binding.^[33]

Treaty: Batum as free port

A fourth example of failure to allege breach of international law is provided by British reaction to Russia’s 1886 declaration that the Black Sea harbour of Batum would no longer be a free port as stipulated in the 1878 Berlin Treaty.^[34]  In Britain, anti-Russian feeling had already been running high because of strong differences over Bulgaria.^[35]  Commenting on this “violation of the Treaty of Berlin,”^[36] British Foreign Secretary Lord Rosebery wrote to Queen Victoria that:

he cannot disguise from himself the certainty that this is meant as a slap in the face of this country. Materially, the question has no importance, as Batum as a free port has no value.  But as an act of insolent perfidy it stands almost alone....  [This unilateral measure] could not be foreseen, even by those who thought they had plumbed the lowest depths of Russian dishonesty.^[37]   

Sharing indignation, Victoria asked her Foreign Secretary what he intended to do about “the astounding news of the insolent and dishonest conduct of Russia in declaring that Batoum is no longer a free port.”^[38]   Lord Rosebery had the British Ambassador in St. Petersburg read the Russian Foreign Minister a dispatch charging Russia with “an infraction of the Treaty of Berlin” casting doubt on “the binding force and sanctity of international engagements.”^[39]   But, as in the 1846, 1870 and 1877 examples, significantly omitted was any charge that international law had been violated by the alleged breach of treaty.

Arbitration treaties, Covenant & World Court Statute

Referring to the Permanent Court of Arbitration established by the 1899 Hague Convention for the Pacific Settlement of International Disputes,^[40] France and Britain in 1903 made a general arbitration agreement soon copied in more than a score of similar treaties by the same and other countries, including the USA.^[41]  Identifying disputes amenable to arbitration, the agreement disjunctively pointed to “differences which may arise of a legal nature, or relating to the interpretation of Treaties existing between the two Contracting Parties.” This separation of legal and treaty disputes was replicated — for example — in a 1903 Franco-Italian convention^[42] and in 1908 USA treaties with Mexico, Italy, Britain, Norway, Portugal, and Spain.^[43]  Other uses of the identical disjunctive text appear in the 1912 general arbitration agreement between Panama and Spain,^[44] the 1913 treaties between Austria-Hungary and Switzerland^[45] and between Portugal and Sweden^[46] and in 1914 British conventions with both Switzerland and Portugal.^[47]  Although applying to “all disputes,” 1911 treaties between Argentina and Venezuela and between Brazil and Italy also distinguished “controversies relating to the interpretation and application of treaties” from those “relating to the interpretation and application of a principle of international law.”^[48]  The same distinction can be found in general arbitration agreements between Peru and Venezuela (1912)^[49] and between Argentina and France (1914).^[50]

Observing that “the term international law has very often been used as not to include treaties,” Clive Parry pointed to “the strikingly late examples of this usage in the text of the Covenant of the League of Nations and even in that of the Statute of the World Court.”^[51]  In the Covenant, the preamble’s aims of co-operation and peace are to be reached “by the firm establishment of the understandings of international law as the actual rule of conduct among Governments.” There then follows a separate call for “the maintenance of a scrupulous respect for treaty obligations in the dealings of organized peoples with one another.”^[52]  Covenant, Article 13, similarly contrasts “disputes as to the interpretation of a treaty” with differences “as to any question of international law.”^[53]  As for the World Court Statute, Article 36(2) “while conferring quasi-compulsory jurisdiction in ‘any question of international law’, provides also for a similar jurisdiction with respect to ‘the interpretation of a treaty’.”^[54]

Notes to Part 3

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[1].  François Fénelon, Examen de conscience sur les devoirs de la royauté composé pour l’instruction de Louis de France, Duc de Bourgogne, in Oeuvres complètes de Fénelon, Archevèque de Cambrai (Paris, 1850), vol. 7:85-102, at § 32:94; his distinction between la foi inviolable des traités on the one hand and droit des gens or droits des nations on the other hand dovetails with the two elements of his pacifist prescription implicitly critical of Louis XIV, see ibid., 95: “To give the world some consistency, and nations some security, above all else preference must be given to two points which are like the earth’s two poles: first, a peace treaty sworn between two princes is for them inviolable and must always be taken in its most natural sense and interpreted according to immediate performance [i.e. early State practice under the treaty]; second, peaceable and uninterrupted possession, from the time that jurisprudence allows for the least favourable prescriptions, must give the one in possession a certain and legitimate property right, whatever his possession’s original defect.  Without these two fundamental rules, there is neither rest nor security for mankind.”

[2].  Robert Plumer Ward, An Enquiry into the Foundation and History of the Law of Nations from the Time of the Greeks and Romans to the Age of Grotius (London, 1795), vol. 2:236-240.

[3].  Lorimer, Institutes, vol. 1:37.

[4].  Parry, “Foreign Policy and International Law,” 91.

[5].  Clive Parry, The Sources and Evidences of International Law (Manchester, 1965), 37.

[6].  See “Law Officers’ Opinions,” in Encyclopedic Dictionary of International Law, ed. John Grant, Anthony Parry, Clive Parry and Arthur Watts (New York, 1986), 211; re legal advice, see Ray Jones, The 19^th Century Foreign Office: An Administrative History (London, 1971), 69-73.

[7].  Martens, Bk. III, Ch. 3, § 24:111; Alphonse Rivier, Principes du droit des gens, vol. 1 (Paris, 1896), 288-289; Federico Diez de Medina, Nociones de derecho internacional moderno, 5^th ed. (Paris, 1905), Part 1, Ch. 1, § 19:140-143.

[8].  Clive Parry, ed. Law Officers’ Opinions to the Foreign Office 1793-1860 (Westmead, 1970), vol. 84:422-426; vol. 85:50-56.

[9].  Brian Jenkins, Britain and the War for the Union, vol. 1 (Montreal-London), 229-232, 244-248, 254-257, 263-265.

[10].  Lawrence’s Wheaton, 819-845; Henry Sumner Maine, International Law: A Series of Lectures Delivered Before the University of Cambridge, 1887 (New York, 1888), 107-122; William Edward Hall, A Treatise on International Law, 8^th ed., ed. Alexander Pearce Higgins (Oxford, 1924), 845-871.

[11].  Viscount Palmerston to Queen Victoria, Mar. 7, 1862, The Letters of Queen Victoria, [hereinafter LQV] 2^nd ser., ed. George Earle Buckle, vol. 1 (London, 1926), 22-23.

[12].  Mar. 10, 1862, Lords, Parl. Deb., 3^rd ser., vol. 165:1237-1243.

[13].  Jenkins, Britain and the War for the Union, vol. 1:255-256.

[14].   William Beach Lawrence, “The Case of the Trent,” in Lawrence’s Wheaton, Appendix No. 3:939-960, at 950: “So far as the United States and England are concerned, there is no subsisting treaty relating to this subject, and the only one which ever existed between them, at all bearing on it, was that of 1794.  It contained no article as to persons, nor could it well have done so, without encountering the inadmissible British municipal pretension of the impressment of seamen from neutral merchantmen....”  Also Jenkins, Britain and the War for the Union, vol. 1:181-202.

[15].  Viscount Palmerston to Queen Victoria, Nov. 29, 1861, in LQV, 1^st ser., ed. Arthur Christopher Benson and Viscount Esher, vol. 3 (London, 1907), 595-596.

[16].  To Foreign Secretary Lord John Russell, Dec. 1, 1861, ibid., 597-598; a right of humanitarian intervention to aid a “suffering people against tyranny” was debated in Apr. 1860 correspondence between Russell and the Queen, see ibid., 505-506.

[17].  Jenkins, Britain and the War for the Union, vol. 1:211-228.

[18].  Diez de Medina, Nociones de derecho internacional moderno, § 19:140-143.

[19].  Memorandum by Queen Victoria, Oct. 17, 1876, LQV, 2^nd ser., vol. 2:487-488.

[20].  Article 1, Additional Treaty between Austria, Prussia and Russia respecting Cracow, signed at Vienna, 21 Apr. (3 May) 1815, in CTS, vol. 64:159-169; Article 6, Act of the Congress of Vienna, signed between Austria, France, Great Britain, Portugal, Prussia, Russia and Sweden, 9 June 1815, ibid., 453-493, at 458; Article 1, Convention between Austria, Prussia and Russia for the Definitive Incorporation of Cracow in Austria, signed at Berlin, 3 (15) Apr. 1846, in CTS, vol. 99:411-415; Wheaton, History of the Law of Nations, 441-445; Lawrence’s Wheaton, 59, 708.

[21].  British and Foreign State Papers: 1846-1847, vol. 35 (London, 1860), 1042-1107.

[22].  Viscount Palmerston to Viscount Ponsonby, Nov. 23, 1846, ibid., 1082-1085.

[23].  Guizot to Count Flahaut, Paris, Dec. 3, 1846, ibid., 1092-1095.

[24].  Articles 11, 13, General Treaty for the Re-establishment of Peace between Austria, France, Great Britain, Prussia, Sardinia and Turkey, and Russia, signed at Paris, 30 Mar. 1856, in CTS, vol. 114:409-420, at 414-415.

[25].  “The denunciation was a symbolic gesture” because Russia then had no interest in a Black Sea fleet, see A.J.P. Taylor, The Struggle for Mastery in Europe: 1848-1918 (Oxford, 1954), 215-216; for the Black Sea question, see David J. Bederman, “The 1871 London Declaration, Rebus Sic Stantibus and a Primitivist View of the Law of Nations,” American Journal of International Law, vol. 82 (1988), 1-40; W.E. Mosse, The Rise and Fall of the Crimean System 1855-1871: The Story of a Peace Settlement (London, 1963), 158-207; Coleman Phillipson, The Question of the Bosphorus and the Dardanelles (London, 1917), 105-109; Serge Goriainow, Le Bosphore et les Dardanelles (Paris, 1910), 222-238; McNair, Law of Treaties, 494-497.

[26].  Circulaire aux Représentants de Sa Majesté L’Empereur près les Cours signataires du Traité du 18/30 Mars 1856, Zarskoé-Sélo, le 19/31 Octobre 1870, Document Nr. 217, Die Große Politik der Europäischen Kabinette 1871-1914: Sammlung der Diplomatischen Akten des Auswärtigen Amtes, ed. Johannes Lepsius, Albrecht Mendelssohn Bartholdy, Friedrich Thimme, vol. 2 (Berlin, 1922), 5-9.

[27].  Circa Nov. 10, 1870, Doc. Nr. 356, The Political Correspondence of Mr. Gladstone and Lord Granville 1868-1876, ed. Agatha Ramm, Royal Historical Society Publications, Camden 3^rd ser., vol. 81 (London, 1952), Part 1: 1868-1871:154-156.

[28].  Cf. Gladstone’s memorandum with Granville’s dispatch, ibid., 154-155, n. 4; for the Nov. 10, 1870 dispatch to St. Petersburg, see McNair, Law of Treaties, 495-497.

[29].  To Queen Victoria, Nov. 12, 1870, LQV, 2^nd ser., vol. 2:82-83; ibid., 87-88, Nov. 26, 1870, Prussia’s Queen Augusta wrote not about violation of international law but rather about “Russia’s violation of the [1856] Treaty,” “arbitrary violation of guaranteed contracts” and “breach of faith and violation of European law.”

[30].  General Treaty for the Re-establishment of Peace between Austria, France, Great Britain, Prussia, Sardinia and Turkey, and Russia, signed at Paris, 30 Mar. 1856, in CTS, vol. 114:409-420.

[31].  Treaty between Austria, France and Great Britain Guaranteeing the Independence and Integrity of the Ottoman Empire, signed at Paris, 15 Apr. 1856, in CTS, vol. 114:497-499; re this treaty, see Lillian M. Penson, “Obligations by Treaty: Their Place in British Foreign Policy, 1898-1914,” in Studies in Diplomatic History and Historiography in Honour of G.P. Gooch, ed. Arshag Ohan Sarkissian (London, 1961), 85-86; Mosse, Rise and Fall of the Crimean System, 185-201.

[32].  A.J.P. Taylor, The Trouble Makers: Dissent over Foreign Policy 1792-1939 (London, 1957), 74-86.

[33].  Apr. 19, 1877, Lords, Parl. Deb., 3^rd ser., vol. 233:1436-1437.

[34].  Article 59, Treaty between Austria-Hungary, France, Germany, Great Britain, Italy, Russia and Turkey for the Settlement of Affairs in the East, signed at Berlin, 13 July 1878, in CTS, vol. 153:171-191, at 189; pop. 8,671 in 1882, Batum was later Russia’s main Black Sea oil port, see Ch. Quelquejay, “Batumi,” in Encyclopaedia of Islam, 2^nd ed., vol. 1 (Leiden, 1979), 1108-1109; Akdes Nimet Kurat, Türkiye ve Rusya (Ankara, 1970), 600-604; for the free port’s closure, see Athanassios Vamvoukos, Termination of Treaties in International Law: The Doctrines of Rebus Sic Stantibus and Desuetude (Oxford, 1985), 72-74; A. L. Kennedy, Old Diplomacy and New 1876-1922: From Salisbury to Lloyd-George (London, 1922), 60-62.

[35].  A.J.P. Taylor, “International Relations,” in The New Cambridge Modern History, vol. 11: Material Progress and World-Wide Problems 1870-1898, ed. Sir F.H. Hinsley (Cambridge, 1967), 556-557.

[36].  Foreign Secretary Lord Rosebery to British Ambassador, St. Petersburg, July 13, 1886, in McNair, Law of Treaties, 498-499.

[37].  Lord Rosebery to Queen Victoria, July 3, 1886, LQV, 3^rd ser., ed. George Earle Buckle, vol. 1 (London, 1930), 152-153.

[38].  Queen Victoria to Lord Rosebery, Windsor Castle, July 4, 1886, ibid., 153-154.

[39].  Foreign Secretary Lord Rosebery to British Ambassador, St. Petersburg, July 13, 1886, in McNair, Law of Treaties, 498-499; also Doc. 173, in Foundations of British Foreign Policy from Pitt (1792) to Salisbury (1902), ed. Harold Temperley and Lillian M. Penson, new impres. (New York, 1966), 436-441.

[40].  CTS, vol. 187:410-428.

[41].  Agreement between France and Great Britain for the Settlement by Arbitration of Certain Classes of Questions which may arise between the two Governments, 14 Oct. 1903, signed at London, in CTS, vol. 194:194-195; Hudson, International Tribunals, 7; James Brown Scott, The Hague Peace Conferences of 1899 and 1907: A Series of Lectures Delivered Before the Johns Hopkins University in the Year 1908 (Baltimore, 1909), vol. 1:329.

[42].  Arbitration Convention between France and Italy, 25 Dec. 1903, signed at Paris, in CTS, vol. 194:365.

[43].  CTS, vol. 206, USA arbitration treaties with Mexico (288-289), Italy (354), Britain (360), Norway (363-364), Portugal (368-369), and Spain (418-419).

[44].  CTS, vol. 216:351-352.

[45].  CTS, vol. 218:354-356.

[46].  CTS, vol. 219:30-31.

[47].  CTS, vol. 220:85-86, 357-358.

[48].  CTS, vol. 214:153-156, 276-279.

[49].  CTS, vol. 215:317-319.

[50].  CTS, vol. 220:141-143.

[51].  Parry, Sources and Evidences, 36.

[52].  Part 1, Preamble, Covenant of the League of Nations, 28 June 1919, signed at Versailles, in CTS, vol. 225:396-406.

[53].  Not in the Feb. 14, 1919 draft, the Article 13 distinction between disputes as to “the interpretation of a treaty” and “any question of international law” was added on advice from former USA Secretary of State Elihu Root, see Michael Dunne, The United States and the World Court, 1920-1935 (New York, 1988), 22-26; Arthur Walworth, Wilson and His Peacemakers: American Diplomacy at the Paris Peace Conference, 1919 (New York, 1986), 306.

[54].  Parry, Sources and Evidences, 37.

Medieval Treaty Obligation

Allen Z. Hertz was senior advisor in the Privy Council Office serving Canada's Prime Minister and the federal cabinet. Formerly he worked in Canada’s Department of Foreign Affairs and taught history and law at universities in New York, Montreal, Toronto and Hong Kong. He studied history and languages at Montreal’s McGill University (B.A.) and then did graduate work in East European and Ottoman history at New York’s Columbia University, where he received his M.A. and Ph.D. He later earned international law degrees from Cambridge University (LL.B.) and the University of Toronto (LL.M.).

Foreword

Most of the work for this paper was done in 1989, when I was a Visiting Fellow of Cambridge University’s Research Centre for International Law, now the Lauterpacht Centre. Recalled with gratitude are the kindness and cooperation afforded by Professor Sir Elihu Lauterpacht and the Centre’s staff. A footnoted version of this article was published in Connecticut Journal of International Law, Vol. 6 (1991), pp. 425-443.

Modern international law places special emphasis on the treaty as a legal source and insists that treaty obligations are legally binding. The late Professor Clive Parry (1917-1982) used to teach Cambridge University law students that before 1919 the moral requirement to fulfill treaty obligations was "binding in honour alone." He also argued that before the First World War publicists and diplomatists regularly excluded treaties from the ambit of international law, which was then conceived to be primarily customary.

This paper on the Middle Ages is part of a larger project that tests the validity of Parry's significant argument, via an examination of treaty obligation in the medieval, classical and modern periods of international law. The Middle Ages are understood as ending with the 16th-century Protestant Reformation. The classical period of international law terminated abruptly with the 1919-1920 Paris Peace Conference, the several treaties of which each included the Covenant of the League of Nations.

Introduction

The present study argues that the medieval treaty was binding in canon law principally by virtue of ecclesiastical jurisdiction over solemn oaths. As Christians, kings were said to be subject to the pope "by reason of sin" (ratione peccati), in this connection, perjury and oath breaking. Also on this website are a dozen March 2012 postings entitled "Treaty Obligation from the Protestant Reformation to 1919" that describe how the Protestant Reformation destroyed Christendom’s legal unity, thereby setting the stage for the emergence of the classical system of international law. As in the Middle Ages, post-Reformation lawyers continued to intone “agreements must be kept” (pacta sunt servanda). But, by contrast with medieval law, the classical framework notably offered no legal remedy for breach of treaty.

The March 2012 postings entitled "Treaty Obligation from the Protestant Reformation to 1919" show that, for approximately 400 years, the moral requirement to fulfill treaty obligations was "binding in honour alone." Therefore, the classical context is one in which particular attention must be paid to the meaning of “honour” and its significance in international law and relations. This topic is thoroughly explored in “Honour’s Role in the International States’ System,” which was posted on this website in November 2009. Also relevant is the February 2012 posting entitled "Peace Bilateral and International: Birth of 'International Peace and Security' as Legal Order and Term of Art."

Those three postings identify the treaty as a major beneficiary of the international-law revolution that occurred at the end of the First World War. The aristocratic emphasis on honour was then replaced by a bourgeois focus on law. The treaty then became an integral part of international law and remarkably rocketed into the number-one position among the sources and evidences of international law. Also there emphasized is the understanding that one of the principal purposes of first the League of Nations and then the United Nations (UN) was to make treaties "legally" binding, as they had been during the Middle Ages.

What Was the Pope’s Jurisdiction?

What today we call “international law” began to emerge in the period from the mid-16th century to the early 17th century. But, casting his mind back to the Middle Ages, Gottfried Wilhelm Leibniz (1693) said that “the divine positive law contained in the sacred Scriptures” was a common tie linking Christians. To the Old and New Testaments, he added the canon law as “the pontifical legislation, to which kings and peoples submit themselves.” On this basis, Leibniz thought that:

before the schism of the last century, it seems to have been accepted for a long time (and not without reason) that a common republic of Christian nations must be thought of.

Leibniz’s Respublica Christiana is an historical commonplace. But, it took systematic study for 19th- and 20th-century scholars to recover two key concepts:

• Medieval society (i.e. Christendom) was understood theologically as Christ’s body (Corpus Christi) and legally as a body ("the church" as a corporation) coextensive with the entire community of the faithful.
• Within Christendom, the pope claimed superior judicial and legislative powers expressed through binding decretal letters prepared by a professional chancery, in its heyday unequalled in Europe.

According to Walter Ullmann (1975): "The basic assumption behind every decretal was papal primacy in the shape of universal monarchic government to be exercised over society which was the Church as the body of clergy and laity alike." A similar understanding had earlier caused Sir Paul Vinogradoff (1923) to include "the world State of medieval Christendom" as one of the "historical types of international law."

The relationship between the universal church’s canon law and a specific territory’s secular law received representative expression in the work of the renowned legist and canonist Baldus De Ubaldis (1327-1400). He believed that, if absolutely necessary, the pope had the power to depose even the Holy Roman Emperor. Secular rulers and secular law were said to be subject to higher norms embodied in natural law, ius gentium and divine law, including canon law. Baldus conceded that secular rulers could legislate contrary to higher norms, but he argued that such legislation would be invalid. In other words, canon law was seen as a limit to secular law and jurisdiction. Canon law and secular law were said to apply in their respective spheres. However, Baldus stressed that the ecclesiastical courts could always take jurisdiction by reason of sin (ratione peccati). Canon law was said to be supreme in spiritual matters, the extent of which was to be defined by the ecclesiastical courts. According to Baldus:

A spiritual case impinging upon a civil one is not heard by a civil, that is a secular judge; but, on the contrary, if a case for a civil court impinges upon a spiritual case, it belongs to the spiritual judge.

 Finally, he claimed that residual power belonged to the church insofar as ecclesiastical authorities could exercise full jurisdiction over any territory lacking secular jurisdiction.

Baldus De Ubaldis (1327-1400)

From the mid-12th century to the eve of the Reformation, the popes were generally lawyers, sometimes even jurists of great distinction. According to Harold Berman (1983):

The papal court of general jurisdiction, both original and appellate, was called in the 12th century, the consistory; the pope himself presided over it. As papal jurisdiction expanded, the popes began to appoint judicial auditors (cardinals, bishops or simple chaplains), whose decisions were binding, subject to papal ratification. In the 13th century, the auditors became a permanent court, called the Audience of the Holy Palace, which deliberated as a body (often divided into sections), and at the end of the century a separate court of appeals was established for civil and criminal cases. In the 14th century a supreme court was established, eventually named the Rota.

The papal court was an institution in many respects comparable to modern international tribunals. According to Walter Ullmann (1970):

The papal court could act both as a tribunal of first instance and as an appellate court. It could become active on its own motion or upon the complaints of a party, be that an individual or a group or a corporate body or a Ruler. Its jurisdiction was unrestricted as to subject matter, persons or territories. No prescriptive time impeded its working. 

The papal court had: (i) compulsory jurisdiction over all Christians including kings; (ii) a mixed judicial-legislative competence to make final legal pronouncements of universal applicability; and (iii) the power to enforce decisions via spiritual sanctions like excommunication and interdict.

What Were the Papal Sanctions?

An “interdict” was a negative command or prohibition directed against an individual, a group or a place. For example, Pope Innocent III placed all of England under an interdict from 1208 to 1213. In the affected area, the use of sacred things was forbidden. The faithful were thus unable to enjoy divine services, including celebration of the mass, public processions and the benediction of the blessed sacrament. Pope Innocent IV (1245) said interdict was an appropriate penalty for the wrongdoing of corporate bodies like cathedral chapters, peoples or tribes.

The most serious ecclesiastical sanction, “excommunication” separated the offender from the communion of the faithful. Apart from general ostracism, excommunication meant exclusion from: Christian burial; public acts of prayer and worship; and the sacraments, including the Eucharist, in which bread and wine were taken as Christ’s body and blood. Excommunication signified the loss of church membership rights. But, the delinquent remained subject to ecclesiastical jurisdiction and bound to Christian obligations. The medieval incorporation of the individual into the church as the body public explains excommunication’s gravity as a legal and social sanction. Sometimes called “the papal arms,” excommunication had a powerful effect precisely because it was based on the religious faith that was then fundamental to society at large.

Excommunication was politically decisive because an excommunicate ruler “was to be shunned by his ministers and his officials and he was to be refused obedience.” Canon lawyers generally agreed that Christians were absolved from their loyalty oaths to an excommunicate king. For example, Pope Innocent IV (1245) excommunicated the Holy Roman Emperor Frederick II. The papal sentence absolved subjects from their oaths of allegiance and instructed them neither to obey Frederick nor to recognize him as emperor or king.

There was agreement between Baldus and his teacher, the civilian Bartolo da Sassoferrato (1314-1357), that an excommunicate ruler could not legislate and an excommunicate judge could not pronounce a valid sentence. Diplomatic relations and treaty making with an excommunicate king were strictly forbidden. This ban was reflected in the coronation oath (1310) of the Holy Roman Emperor Henry VII. He had to promise that he would never enter into relations, alliance or agreement with anyone standing outside the community of the Catholic faith. And, a sentence of excommunication voided prior agreements. For example, “earlier alliances were broken off and treaties that had been painfully negotiated were trampled underfoot,” when Pope Clement V (1309) excommunicated leading Venetians and placed an interdict on the Republic of Venice. Sworn agreements with England’s King Henry VIII were specifically invalidated when he was excommunicated by Pope Paul III in 1535. Furthermore, the papacy might proclaim a crusade against a king who continued to defy one year of excommunication and interdict.

Medieval Treaties Binding in Canon Law?

The world was familiar with the treaty and the question of treaty obligation long before the emergence of the modern State and the pluralistic States’ system with its distinctive international law. In the early 19th century, international-law scholar Henry Wheaton wrote:

The law of nations acknowledged by the ancient Greeks and Romans was exclusively founded on religion. The laws of peace and war, the inviolability of heralds and ambassadors, the right of asylum, and the obligation of treaties, were all consecrated by religious principles and rites. […] Treaties were sanctioned with solemn oaths, the violation of which it was believed must be followed by the vengeance of the gods.

Wheaton here referred to classical antiquity, but the remarks are an excellent starting point for an understanding of the medieval treaty, which was an agreement between Christian kings, concluded within the context of their common faith. The legitimacy of a treaty between a Christian and a non-Christian ruler was therefore problematic. Medieval history records many agreements between Christian and Muslim potentates. However, a ban on relations between the faithful and unbelievers, prohibita communio fidelis cum infideli, was generally the church’s theoretical position.

The medieval treaty was a holy contract inseparably bound up with the key institution of the sacred oath and the canonical provisions punishing perjury and other oath violations. According to the New Catholic Encyclopedia:

An oath is the invocation of the name of God in witness to the truth. It may be taken only in accordance with the truth, with prudence, and with justice. The intention of calling God to witness to the truth of a statement (assertory oath) or a promise (promissory oath) must be sincere and sufficiently manifest to others in words or unmistakable signs. A person is bound by a special and personal obligation of religion to fulfill what he has freely promised by oath to do.

In the strictest sense, perjury is lying under oath, i.e. intentionally swearing to the veracity of a statement known to be false. According to the New Catholic Encyclopedia:

A lying, or perjured, oath is always a mortal sin because it involves contempt for God and disrespect for his attributes. The perjurer asks God to be witness to a lie or supposes that God can be deceived. Perjury is one of the most serious offences against the virtue of religion; it contains the malice of contempt for God.

There is clearly an important distinction between subsequent, willful failure to fulfill a sworn promise and the making of a knowingly false statement under oath. The latter constitutes the grave offence of perjury; the former is also a sin, but its seriousness depends on the circumstances of the particular case. But, the Middle Ages significantly tended to use “perjury” broadly to cover both sworn falsehood and subsequent willful failure to perform an oath obligation. Willful violation of a promissory oath is still regarded as perjury in some European countries.

The Bayeux tapestry indicates that Harold swore an oath to back his promise to help William Duke of Normandy become King of England

According to Ernest Nys (1894), the oath necessarily gave the medieval treaty a “religious character” which allowed the papacy to take judicial notice of any breach of treaty. For Joycelyne Dickinson (1955), the key point about medieval thought on treaties was that:

They were invested with a special solemnity, because they were usually ratified by oaths, to break which involved the sin of perjury which was a spiritual offence. This was true whether the oath had been taken at a great ceremony, in the hands of a papal legate or senior ecclesiastic, and before a great gathering of people, or whether it was exacted by a local official in pursuance of a clause in the treaty calling for widespread oath-taking in the dominions of the contracting parties. In either case, the oath to the treaty would be a sanction which could, in the last resort, be enforced with heavy ecclesiastical penalties, but which was, in the first place, a matter of conscience.

The medieval approach to treaty obligation was well expressed in an oration (1518) of the Tudor divine and diplomatist Richard Pace. He preached on the “Universal Peace” between England and France in the presence of England’s King Henry VIII, his Lord Chancellor Thomas Wolsey, the Papal Legate Cardinal Lorenzo Campeggio and the French ambassadors. The sermon was at London’s Saint Paul’s Church, where “this most religious treaty” between Kings Henry VIII and Francis I was proclaimed and ratified.

O happy pair of Kings! You are today about to give a most auspicious beginning to three things: to the treaty; to faith; and to peace: to the treaty, that it shall be entered into with holiness; to faith, that it shall be sincere and inviolable; to peace, that it shall be perpetual. […] So may immortal God bring it to pass that the joy we feel at this most healthful peace, formed and entered into in this church today, shall be solid and perpetual for all Christians. Of this inestimable blessing the sacred oaths with which this holy treaty has been confirmed give me a sincere hope. He who shall not fear to violate these oaths shall sink his body and soul together into the depths of Hell and the Gehenna of fire.

How Were Medieval Treaties Made?

Used as examples of medieval treaty making will be the Paris Treaty (1259), the Arras Treaty (1435) and the Cateau-Cambrésis Treaty (1559). These agreements are featured for three reasons. First, they have been examined in detail by modern historians. Second, their parties (England, France, Burgundy, Spain) were major participants in the European diplomacy of their day. Third, from a political viewpoint, they were substantively important as peace treaties.

Through the Paris Treaty (1259), England’s King Henry III and France’s King Louis IX sought to end a half-century dispute over Normandy, Anjou, Touraine, Maine and Poitou. The treaty was made in four main stages: pax inita (beginning peace); pax firmata (affirming peace); ratificacio (ratification); and publicacio (publication).

Pax inita: In 1257 papal pressure pushed King Henry III to Paris pourparlers. The English king (May 1258) gave five envoys letters of proxy (littere procuratorie) with full powers (plena postestas) to act on his behalf. Simon de Montfort, Hugh Bigod, Peter of Savoy, and Guy and Geoffrey de Lusignan were authorized to go to Paris to extend the truce and negotiate a definitive peace. Furthermore, the king empowered them to swear solemn oaths on his soul (juramentum in animam regis) that he would keep the truce and abide by the treaty terms. Observed by papal envoys, bilateral negotiations (tractatus) yielded articles of peace (composicio pacis) passed under the seals of the Archbishop of Tarentaise, probably acting for Henry III, and the Archbishop of Rouen for Louis IX. The document was then kept safe in the Paris Temple which was headquarters of the Knights Templar, a crusading order directly under the Pope’s authority.

Pax firmata: On May 28, 1258, the French and English delegations met with Louis IX. In Henry III’s name, Simon de Montfort, Peter of Savoy and Hugh Bigod swore that the English king would fulfill the agreed terms, provided that Louis IX would accept the treaty by Candlemas (February 2, 1259). The three English envoys gave Louis IX a sealed document containing the articles of peace and the text of their oaths. In Louis IX’s name, two French negotiators then swore that their king would fulfill the agreed terms on two conditions. First, for his remaining territory in France, Henry III had to do homage to Louis IX. Second, Henry III and his sons had to deliver letters patent recording their personal oaths to observe the treaty. The articles of peace and the oaths sworn by the French negotiators were then embodied in a sealed document given to the English envoys.

Around Candlemas 1259, three French envoys arrived in England where they announced that Louis IX had accepted the treaty. Henry III designated William de Fortibus and Humphrey de Bohun as “proctors” with full powers to swear on his soul that we would fulfill the treaty terms. On February 17th the two proctors took the oath at Westminster in the presence of Henry III and the French envoys. The text of the oath was then recorded in a document which was sealed and given to the French delegation. In subsequent separate ceremonies, Henry III’s two sons Edmund and Edward swore that they too would observe the treaty. Letters patent recording Edmund’s oath were carried to Louis IX and there must have been a similar document for Edward.

Ratificacio and publicacio: Louis IX received from the English baronial council a paper confirming the articles of peace and from Edward and Edmund sealed documents indicating acceptance of the treaty. Through envoys, the two kings exchanged ratification instruments in October 1259. Henry III travelled to Paris, where he met with Louis IX and participated in a ceremony publishing the treaty on December 4, 1259. Louis IX then received homage from Henry III for his remaining territory in France.


1259 King Henry III's homage to Louis IX

1435 Arras Treaty “Religious”?

The Arras Treaty was concluded between Charles VII, King of France, and Philip III, Duke of Burgundy. The Hundred Years’ War (1337-1453) found its turning point, because Burgundy decided to quit the 1420 Treaty of Troyes -- the alliance with England that had almost defeated France. The delegations met in the Saint Vaast Abbey, where mediation was provided by Cardinal Nicolo Albergati acting for the pope and the Cardinal of Cyprus for the General Council of the Church at Basle. The text was agreed after lengthy negotiations, in which the mediators played an active role. The two cardinals may even have met with each of the parties separately, after the fashion of the cross-examination of witnesses by judges in ecclesiastical courts. In article 40, the parties acknowledged that breaches would be sanctioned by interdict and gradually intensifying penalties of excommunication (aggravatio and reaggravatio). Vassals would be absolved from their loyalty oaths to the party beaching his promise. Furthermore, principal vassals would be required to ratify the treaty and swear to keep the peace. They would also be obliged to accept a positive duty to renounce their allegiance should their ruler prove to be a treaty breaker (articles 39, 41).

The document was promulgated before a great assembly in the Saint Vaast Abbey Church on Saint Matthew’s Day (September 21st). Duke Philip III and the French ambassadors were asked whether they would faithfully observe the oaths which they were about to take. The Cardinal of Cyprus celebrated the mass of the Holy Spirit. The gospel was read by the Abbot of Saint Vaast and the epistle by the Abbot of Saint Nicholas of Reims. The Duke’s confessor, the Bishop of Auxerre, preached a sermon on reconciliation and fraternal union. The Cardinal of Cyprus presented a cushion bearing a golden cross and the Eucharist. Duke Philip III swore a solemn oath that he would forget his father’s assassination (1419) and pardon the guilty. Acting for the King of France, the Dukes of Bourbon and Richemont together put their hands on the cross and asked Duke Philip III to forgive King Charles VII for the 1419 murder. The two cardinals placed a hand on Philip III’s head and absolved him from the oath that he had taken to the 1420 Troyes Treaty with England. The cardinals repeated the absolution rite for the Burgundian lords who had also taken personal oaths to the Troyes Treaty. There followed an hour-long reading, first of the two cardinals’ respective papal and conciliar procurations, and then of the text of the new Arras Treaty. The congregation cried “Noel!” which, in medieval French, was figurative usage expressing joy at the final arrival of a long-awaited happy event. Duke Philip III swore to uphold the new treaty by an oath made on the gospels held by the two cardinals. His oath was then recorded in ratification letters issued that same day. Acting for King Charles VII, the French ambassadors solemnly swore to fulfill the new treaty and these oaths were also documented. The entire congregation was asked to raise the right hand and, in common, to take an oath to respect the treaty. The ceremony was concluded with the benediction.

Philip III Duke of Burgundy

Duke Philip III was eager to have the Arras Treaty ratified by both the pope and the Council of Basle. The mission to the pope at Florence was successfully entrusted to the Priest of Autun, Nicolas Goguet (November 1435). At the same time, Besançon Dean Jean Fruyn secured letters of ratification from the Council of Basle.

King Charles VII

France’s King Charles VII ratified the Arras Treaty in Saint Martin’s Church, Tours (December 10, 1435). Archbishop of Crete, Fantinus Valareso said mass for a congregation, including the princes and nobles. Also present were the Burgundian ambassadors, Bishop Rolin of Noyon and Jean de Croy. The royal chancellor summarized the treaty and explained its purpose. Kneeling before the archbishop’s chair, King Charles VII swore to keep the treaty with an oath which he gave, while touching the New Testament lying on the archbishop’s lap. The same oath was taken individually by the princes and principal nobles, and the rest of the congregation raised the right hand and swore a general oath. They all then shouted “Noel!” King Charles VII shook hands with the Burgundian ambassadors and an organ accompanied singing of Te Deum.

1559 Cateau-Cambrésis Treaty Religious?

The agreement was a landmark in the long-standing struggle between two powerful European dynasties, the Valois (France) and the Habsburgs (Spain and the Low Countries). Negotiations began at the Cistercian Abbey of Cercamp and continued at the bishop’s residence at Le Cateau near Cambrai. On April 3, 1559, ambassadors of King Henry II of France and King Philip II of Spain signed the articles of peace, which had been engrossed on parchment. Although the Protestant Reformation had already torn the fabric of Europe’s legal unity, “the Most Christian King” of France and “the Catholic King” of Spain both remained firmly within the framework of the Roman Church.

The treaty was proclaimed on the same day in Le Cateau’s parish church, in a ceremony that included the Te Deum and mass. Religion was also reflected in the treaty’s preamble:

God has moved two great Princes… to seek an end to the disputes and differences of the war between them, and to transform it into a good, final, complete, sincere and durable Peace.

The medieval worldview lived on in the stipulation that the monarchs swear solemn oaths:

They [the signatory ambassadors] also undertake that the Catholic King shall, as soon as can be, take an oath to the treaty, in the presence of the representatives of the Most Christian King, on the Holy Gospels, and the Canon of the Mass, and on his honour. The Most Christian King shall do likewise, in the presence of the representatives of the Catholic King.

King Philip II ratified the treaty at a ceremony in the Coudenberg Palace Chapel at Brussels, on Whit Monday (May 15, 1559). After mass was said by the Bishop of Arras, Antoine Perrenot de Granvelle, King Philip II and the French ambassadors approached the high altar. Placing his hand on what was believed to be a relic of the true cross, the King of Spain promised to observe the treaty’s terms. On June 18, 1559, the King of France and the Dauphin performed the same rite in a ceremony at Notre Dame Cathedral in Paris.

Kings of Spain and France Embrace
Cateau-Cambrésis Treaty 1559

Kings Lacking Jurisdiction over Treaties?

The medieval concept of sovereignty was fundamentally personal, i.e. the sovereign was identified with the ruler as a natural human being. The medieval lawyer tended not to distinguish between public and private law, between a diplomatic envoy and an ordinary agent. For example, arbitration between two private individuals or between two rulers followed the same procedure, drawn from Roman law. Within this context, it is hardly surprising that treaties were considered to be nothing more than the contracts of kings. This perspective explains how the Roman ius gentium -- a body of private law governing individuals, their transactions and property -- was later able to father the system of public law for independent States. But, for understanding medieval treaty obligation, it is far more significant to appreciate that there was then an identity of contract and treaty. The former may therefore be used to explain the latter. In other words, the juridical position of the medieval treaty can be fixed by turning to medieval material on the law of contract.

For example, Baldus believed that a prince’s contracts were binding in both natural law and ius gentium. This emerges from his analysis of the feudal relationship. According to Joseph Canning (1987):

Baldus like all jurists sees the feudal bond as being based pre-eminently upon the most fundamental legal relationship, contract, without which human intercourse and society would be impossible. The sanctity of contract, and the fides involved in keeping it, are so fundamental that they are seen as the product of ius naturale or ius gentium, and are prior to any positive-law power possessed by the emperor, and limit him as anyone else. Thus, the divinely approved commission of power to the emperor does not include the plenitude of power over contracts, and especially feudal ones, a limitation he shares, for instance, with the king of France -- in feudal matters, both must observe due process of feudal law.

With reference to the jurisdiction of the secular ruler, Baldus was emphatic: “God has subjected the laws to him, but has not subjected to him contracts by which he is bound.” And, elsewhere he said: “Although the emperor is not bound by positive law, he is bound by the law of contract.” Furthermore, Baldus argued that contracts relating to the nature of the ruler’s office are also binding on his successors. This legal opinion was given for the feudal nexus between lord and vassal -- a relationship between superior and inferior. As a contract between equals, a treaty between two kings would be an a fortiori instance of his argument. Consequently, Baldus would have had no hesitation affirming that secular rulers are also bound by their treaties.

Papal Jurisdiction over Treaties?

Studying medieval diplomacy, Donald Queller (1967) concluded that, “truces, treaties and alliances are merely special forms of conventions or contracts.” This view is supported by a look at treaty-making procedures, which used instrumentalities drawn from private law. For example, “procuration” was a private-law institution that authorized an agent with full powers (plena postestas). From Roman law, procuration passed into diplomatic usage, probably via canon law:

The procurator was a sort of agent, used primarily in business affairs or before a court. The identical instrument was, however, gradually found serviceable for governmental administration or diplomacy.

In other words, procurators were first employed for negotiating private contracts for their principals and only later for treaties between rulers.

Canon law saw no difference between a treaty and a contract. “Agreements must be kept” (pacta sunt servanda) was the principle of penitential discipline that applied to either treaty or contract. The canonical theory was that “an oath and a promise are equal in the sight of God… not to fulfill the obligations of a pact is equivalent to lie.” Depending on the circumstances, the breach of a promise might itself be grave enough to deserve ecclesiastical censure by reason of sin (ratione peccati). But, in practice, the parties to treaties and contracts were not satisfied with simple promises or pacts. They were Christians who, frequently for contracts and always for treaties, reinforced their obligations with the swearing of solemn oaths. This was the decisive aspect which ensured that the church was allowed to decide both contract and treaty disputes. Oaths including pledges of faith were by reason of subject matter (ratione materiae) under ecclesiastical jurisdiction.

In the New Testament (Matthew xvi, 18-19), Saint Peter is promised the keys to the kingdom of heaven and told: “Whatsoever you will bind on earth will be bound in heaven and whatsoever you shall loose on earth shall be loosed in heaven.” According to Walter Ullmann (1978), Saint Peter’s keys became in the pope’s hands keys of law (claves juris).

St. Peter's keys in the Vatican Coat of Arms

The pope was regarded as “living law” (lex animata) and “ordinary judge of all” (iudex ordinarius omnium). He had the power of binding and loosing (postestas ligandi et solvendi) which was understood juristically. As both legislator and judge, the pope could bind with law or judicial sentence. He could also loose by amending or repealing law or reversing a judicial decision. And, most relevant to matters of contract and treaty, the pope could release either a private individual or a king from a sworn obligation. This was a dispensation comparable to the solutio obligationis of Roman law. An excellent example is the aforementioned release of Duke Philip III of Burgundy from his sworn obligation to uphold the 1420 Troyes Treaty, the alliance with England.

The possibility of a papal dispensation was well known, so parties sometimes explicitly agreed to refrain from applying to the pope for release from a treaty oath. For example, precisely this stipulation was inserted into the 1360 Brétigny Treaty between the kings of England and France.

1360 Brétigny Treaty

The papacy was especially active in relation to treaties which feature frequently in the registers kept by the papal chancery. There are many examples of kings submitting their agreements to the pope for approval, confirmation, ratification, or nullification. In the late 15th century, France’s King Louis XI told his ambassadors that ratification by the pope was still the best way to ensure the performance of a treaty obligation.

Medieval Case Law for Breach of Treaty?

According to Harold Berman, cases alleging breach of a solemn oath (causa fidei laesionis seu perjurii), like other ecclesiastical causes, were started:

by filing a complaint in the court of the appropriate archdeacon or bishop, and an appeal could be taken by the losing party to the court of the appropriate archbishop and thence to the court of the pope in Rome…. The pope also exercised a universal original jurisdiction: the plaintiff could impetrate (procure) a writ from the papal curia nominating papal delegates to try any case locally. This, indeed, was quite common in cases involving considerable sums of money, as well as in cases in which the parties resided in different archbishoprics.

King John of England turned to the papal court at Rome to make a “denunciation” against King Philip Augustus of France. The allegation was that, in April 1202, Philip had resumed hostilities against John’s mainland possessions in contravention of a solemn truce, backed by the sacred oath of both parties. King Philip Augustus began by contesting the court’s jurisdiction. He argued that Rome had no right to interfere in a quarrel between kings and emphasized that John was also his vassal. Pope Innocent III replied with the decretal Novit ille (1204). The pope conceded that the Church had no business meddling in feudal affairs per se, but claimed jurisdiction, because the case involved a question of sin, i.e. the allegation of the breach of a solemn oath. Moreover, Pope Innocent III took this occasion specifically to affirm that the breaking of peace treaties (rupta pacis foedera) was subject to canon law on the facts of the case (ratione causae). A papal legate was therefore dispatched to Meaux, where a council began proceedings for "censures" against Philip Augustus. The French bishops then appealed to Rome, where representatives of both kings were summoned. Because John’s representatives failed to appear, King Philip Augustus won by default. This litigation was a reflection of the contemporary political constellation which cost King John most of his territories on the continent.

In 1337, France’s King Philip VI took away the Duchy of Guyenne from England’s King Edward III. The English considered this to be a violation of the treaties between England and France. A contemporary legal opinion advised Edward to appeal to the pope’s compulsory jurisdiction (full apostolic powers) by reason of sin (ratione peccati). The proposal envisaged a papal judgment ordering the King of France to restore the confiscated province on pain of excommunication and interdict.

Kings Wary of Pope’s Compulsory Jurisdiction?

Medieval legal sophistication is evident in the distinction which contemporaries made between the pope’s compulsory jurisdiction (full apostolic powers) and instances where the disputing parties agreed to submit their case to the pope for either mediation or arbitration. Medieval rulers sometimes volunteered to accept papal mediation or arbitration, but they were generally wary of compulsory jurisdiction flowing from the pope’s full apostolic powers. For example, Pope Boniface VIII (1295) sought to use his compulsory jurisdiction to order a peace treaty between England’s King Edward I and France’s King Philip IV. Despite application of ecclesiastical sanctions, Philip IV refused to obey the pope. However, Philip IV was willing to authorize Pope Boniface VIII to arbitrate in his private capacity as Signore Benedictus Gaytanus. “As if a private person” (tamquam in privatam personam), Pope Boniface VIII gave his arbitral award on June 27, 1297.

The distinction between the pope’s compulsory jurisdiction and voluntary submission to papal mediation or arbitration was again recognized in 1300, when King Edward I invited Pope Boniface VIII to settle a new dispute with the King of France. The pope replied to the English envoys that he had considered the matter carefully, but did not believe that it could be settled through mediation because the French would make unreasonable demands:

And, if we will arbitrate, the French will not execute our award; it would not even be possible to force them to do it by making them pay a fine, about which they will worry very little. This is why we believe that it would be good if we would use our full apostolic powers. For us to be able to do this, it would be necessary that complaints against the king of France are formulated for us and that it is alleged that he has committed a sin by wrongfully retaining territory belonging to the king of England. [...] If the king of France argues that we do not have the authority to intervene in questions of fiefs, we will reply that we do by reason of sin.

Treaty Obligation's Link to the Search for Peace

Modern international law says the system’s rules are based on the consent of States expressed in their practice. And, the Statute of the International Court of Justice regards the best evidence of State practice to be treaties as “establishing rules expressly recognized by the contesting States.” The preamble to the UN Charter points to “respect for the obligations arising from treaties” as one of the organization’s main aims. UN Charter, Article 102 requires that every treaty made by UN Members be registered with the Secretariat and published. Article 36 of the Statute of the International Court of Justice invites States to opt to recognize the court’s compulsory jurisdiction over treaty interpretation.

The UN Charter is itself a treaty. Although it deals with a variety of additional topics like human rights and economic and social development, the UN Charter focuses on maintenance of international peace and security. Thus, UN Charter, Article 2(4) prohibits the “use of force against the territorial integrity or political independence of any State.” Because UN membership is near universal, an act of aggression is normally also a treaty violation. The point is fundamental, because peace treaties have always been among the most significant agreements between States. This invites the key question: are peace treaties legally binding? Is there now an effective international remedy for an egregious violation of the treaty obligations that States accepted when they joined the UN?

As students of international law and politics soon learn, the answer is complicated, and can only reveal a varying gap between theory and practice, aspiration and performance. In the Middle Ages, there was also appreciation for the uncomfortable gap between theory and practice. But, the medieval search for peace continued even though the goal seemed impossible to attain. Our own century shares with that earlier age the attempt to make treaties binding in law. In measuring our own task and judging our accomplishment, can we ignore the efforts and experience of those who did the same work not so long ago?