International law has been defined to be "the rules which determine the conduct of the general body of civilized states in their dealings with each other" (American and English Encycl. of Law). Different writers have given varying views of the foundation of the law of nations, some holding that it is founded merely upon consent and usage, and others that it is the same as the law of nature, applied to the conduct of nations in the character of moral persons susceptible of obligations and laws. Chancellor Kent holds that neither of these views is strictly true; that the law of nations is purely positive law founded on usage, consent, and agreement, but that it must not be separated entirely from natural jurisprudence, since it derives its force "from the same principles of right reason, the same views of the nature and constitution of man, and the same sanction of Divine revelation, as those from which the science of morality is deduced". It follows, then, that by the natural law every state is bound to conduct itself towards other states in accordance with the rules of justice, irrespective of the general rules that have arisen from long established custom and usage. International law is a part of the law of the land of which the courts take judicial notice, and municipal statutes are construed so as not to infringe on its doctrines. The rules of international law are to be found in writers of recognized authority, in treaties between civilized nations, in the decisions of international tribunals, in state papers and diplomatic correspondence, and its application is to be sought especially in the decisions of the courts of the different nations where the rules have been defined in litigated cases, arising especially in the admiralty where judgment has been sought in prize cases. The first great modern authority on the subject was Grotius. His works have been followed by those of Puffendorf, Burlamaqui, Bynkershoek, and Vattel. The works of these learned authors have been adapted and expanded by various writers, so that now there is a vast body of literature upon the subject representing great learning and ability.
The law of nations is essentially the product of modern times. Ancient nations looked upon strangers as enemies, and upon their property as lawful prize. Among the Greeks prisoners of war might lawfully be put to death or sold into slavery with their wives and children, and there was no duty owed by the nation to a foreign nation. Some beginnings of diplomatic intercourse may be traced in the relations of the Greek states towards one another, by agreements relating to the burying of the dead and the exchange of prisoners, while the Amphictyonic Council affords an instance of an attempt to institute a law of nations among the Grecian states themselves. The Romans show stronger evidence of appreciation of international law, or at least of the beginnings of it. They had a college of heralds charged with the Fetial Law relating to declarations of war and treaties of peace, and as their power and civilization grew, there came an appreciation of the moral duty owed by the state to nations with which it was at war. After the establishment of the empire, especially in its later periods, the law of nations became recognized as part of the natural reason of mankind. After the fall of the empire there was a relapse into the barbarism of earlier ages, but, when in the ninth century Charlemagne consolidated his empire under the influence of Christianity, the law of nations took on a new growth. As commerce developed, the necessity of an international law providing for the enforcement of contracts, the protection of shipwrecked sailors and property, and the maintaining of harbours, became more apparent. Various codes and regulations containing the laws of the sea gradually developed, the most famous of which are the "Judgments of Oléron", said to have been drawn up in the eleventh century and long recognized in the Atlantic ports of France and incorporated in part in the maritime ordinances of Louis XIV; the "Consolato del Mare", a collection of rules applicable to questions arising in commerce and navigation both in peace and war, probably drawn up in the twelfth century and founded upon the Roman maritime law and early maritime customs of the commercial cities of the Mediterranean; the "Guidon de la Mar", which dates from the close of the sixteenth century and deals with the law of maritime insurance, prize, and the regulations governing the issue of letters of marque and reprisal. In addition to these there were various bodies of sea laws notably the maritime law of Wisby, the customs of Amsterdam, the laws of Antwerp, and the constitutions of the Hanseatic League. All of these codes contained provisions extracted from the earliest known maritime code, the Rhodian Laws, which were incorporated into the general body of Roman law, and were recognized and sanctioned by Tiberius and Hadrian.
During the long period between the fall of the Roman Empire and the definitive beginning of modern European states the greatest influence working for a recognition of international law among all peoples was the Church. A common faith, imposing the same obligations upon the individual members of the Church among all nations, obviously tended to the establishment and recognition of rules of justice and morality as among the nations themselves; and, when the more general acceptance of the obligations of Christianity became the rule, it followed naturally that the Head of the Church, the pope holding the Divine commission, should become the universal arbiter in disputes among nations. For centuries the great offices of state, especially those having to do with foreign relations, were held by bishops learned in canon law, and, as canon law was based upon Roman law and especially adapted to the government of the Church whose jurisdiction was not bounded by state lines, it naturally suggested many of the rules that have found a place in international law. The pope became the natural arbitrator between nations, and the power to which appeals were made when the laws of justice and morality were flagrantly violated by sovereigns either in relation to their own subjects or to foreign nations.
As the empire founded by Charlemagne gained in power and extent, the controversies precipitated by the conflicting claims of civil and ecclesiastical jurisdiction developed still further the position of the pope as the highest representative of the moral power of Christendom. It has been justly said therefore that, "of all the effects of Christianity in altering the political face of Europe throughout all its people, and which may therefore very fairly be denominated a part of its Law of Nations, none are so prominent to observation during these centuries as those which sprang from the influence and form of government of the Church" (Ward, "Law of Nations", II, 31). At first without territory or temporal power, on account of his spiritual influence alone the pope was recognized as the ultimate tribunal of Christendom, and as such was known as the Father of Christendom. Under the Holy Roman Empire from the time of Otho I, as is pointed out by Janssen, there was a close alliance between the Church and the State, though they were at no time identical. "Church and State", he says, "granting certain presupposed conditions, are two necessary embodiments of one and the same human society, the State taking charge of the temporal requirements, and the Church of the spiritual and supernatural. These two powers would, however, be in a state of continual contention were it not for a Divine Law of equilibrium keeping each within its own limits." He points out further that the original cause of the separation between the spiritual and temporal powers, as "taught by Pope Gelasius at the end of the fifth century, lies in the law established by the Divine founder of the Church, Who, 'cognizant of human weakness, was careful that the two powers should be kept separate, and each limited to its own province. Christian princes were to respect the priesthood in those things which relate to the soul, and the priests in their turn to obey the laws made for the preservation of order in worldly matters; so that the soldiers of God shall not mix in temporal affairs, and the worldly authorities shall have naught to say in spiritual things. The province of each being so marked out, neither power shall encroach on the prerogatives of the other, but confine itself to its own limit.'"
"While it is recognized that the kingdoms of this world, as opposed to the one universal Church, may exist and prosper while remaining separate and independent, yet it was thought that the bond with the Church would be of a higher nature if the partition walls between people and people were broken down, all nations joined together in one, and the unity of the human race under one lord and ruler acknowledged. It was this idea which inspired the popes with the desire to found the Holy Roman Empire, whose Emperor would deem it his highest prerogative to protect the Christian Church. The Gospel was to be the law of nations. The State would consolidate the nations, while the Church would sow the seeds of revealed truth" (Janssen, "History of the German People", II, 110 sq.). In this ideal we find the medieval conception of the State. Although the ideal was never completely realized, yet it met such general acceptance that the emperor became the chief protector of law and order and the arbiter between lesser princes. The growth of the power of the State gradually diminished that of the feudal barons, whose petty contentions and the violence of whose lives were a hindrance to the development of international justice. Until this phase of the beginnings of civilization changed there was little to ameliorate the brutality of conduct between warring peoples, except as the individual education of knights in chivalry affected their conduct.
Another influence of great importance in the formation of international law were the general councils of the Church, affecting as they did all Christian nations and laying down rules of faith and discipline binding alike upon individuals and governments. The history and development of rules of international law from these early beginnings have been traced to contemporary times, and, notwithstanding periods when the influence of a lofty and Christian ideal of the relations between nations seems almost to have been lost, it will appear that there has been a steady advance in the recognition of the existence of a moral law of nations whose sanction is the public opinion of the world. So far has this system progressed that its underlying principles are, in the main, well-defined, universally recognized, and constantly appealed to, both in times of war and in times of peace, by all civilized nations. Rules governing the acquisition of territorial property, jurisdiction over rivers and seas, protectorates over independent peoples; measures allowed to compel the rendering of justice, short of war; intervention in the affairs of foreign nations, have all been measurably settled; and so far as relates to the rights and duties of belligerents and of neutral states in declaring and carrying on war, the fixing of the character of property, the regulating of the effect of intercourse between individuals, many vexed points have also been carefully defined and to a large extent settled. Some of the most delicate questions, such as the right to visit and search the blockaded ports of the enemy, and the character of correspondence permitted between the subjects or citizens of neutral states and the belligerents, may be considered as well settled and recognized by decisions of the highest courts of all civilized nations as any of the rules of municipal law.
Earnest and intelligent efforts to bring about a permanent court of arbitration have resulted in the formation of an international tribunal at The Hague, which has already been accepted by the voluntary action of the various nations as a proper forum for the decision of many international questions specially referred to it. The principles of arbitration accepted by the United States and Great Britain in the settlement of the so-called Alabama Claims and the frequent agreements between the contending parties over questions of boundary, fisheries, and damages to private property of their respective citizens or subjects, have given emphasis to international law. Its rules have enforced respect for private property on the part of contending armies, and, under certain conditions, when such is carried by ships, have forbidden the use of certain destructive missiles, and in very many ways have alleviated the horrors of war. While there must always remain questions that no self-respecting nation would be willing to submit to arbitration, yet the field for the exercise of the latter is indefinitely great, and, as the demands of modern civilization, the means of communication between nations, and the development of trade relations increase, questions more frequently arise requiring appeal to some tribunal, acceptable to both parties, whose decision shall be final and absolute. Until the revolt against the Church in the first quarter of the sixteenth century, this power of arbitration, as has been stated, rested in the pope. With the decline of recognition of this moral power, religious sanctions in the relations between nations have gradually lessened. Instead of a decision of the pope, bearing with it the impress of the revealed truth of religion, the agreements of modern courts of arbitration or other referees for the settlement of international disputes have for their sanction the general sense of justice existing naturally among men, strengthened by such faith in revealed religion as may exist among them irrespective of the teaching of the Church. This is the great difference between the sanction of modern international law and that existing previous to the so-called Reformation. Previous to that event the power of the Church was exercised merely in a moral way by an appeal to the faith and consciences of all men and nations, enforcing the decrees of the arbiter of Christendom — the pope.
Controversy concerning this arbitration has been carried on, at first with great violence, but since with a calmer and fairer recognition of the exceeding advantage to nascent civilization of such power as that exercised by the popes during the Middle Ages. It has been insisted that the popes not alone wished to vindicate their supreme spiritual power, but cherished a desire to reduce all princes to a condition of vassalage to the Roman See. This is a grave error. The Church has never declared it to be an article of faith that temporal princes, as such, are in temporal matters subject to the pope. The confusion of thought has arisen from the fact that in the eyes of the Church the kingly power has never been looked upon as absolute and unlimited. The rights of the people were certainly not less important than those of the ruler, who owed them a duty, as they owed a duty to him. They did not exist for his benefit, and his power was to be employed, not for his own ends, but for the welfare of the nation. He was to be, above all, the servant of God, the defender of the Church, of the weak, and of the needy. In many states the monarch was elected only on the express condition of professing the Catholic Faith and defending it against attack. In Spain, from the seventh to the fourteenth century, the king had to take such an oath, and, even when it was no longer formally administered, he was still understood to be bound by the obligation. The laws of Edward the Confessor, published by William the Conqueror and his successors, expressly provide that a king who does not fulfil his duties towards the Church must forfeit his title of king. Kings were constantly reminded that their temporal power was given them for the defence of the Church, and that they should imitate King David in their submission to God.
With this intimate relation of Church and State, the clergy, by reason of their education and force of character and the respect paid to them because of their office, took an active part in the civic affairs of the various nations, and, until the controversies arose between them and the emperors who succeeded Charlemagne, the civil and religious powers existed harmoniously in the main. Owing to the limitations of human nature, and especially because the support of both Church and State necessarily came from voluntary or enforced contributions of the people, causes of friction would arise from time to time between the two powers. The decrees of the councils of the Church were confirmed as laws of the empire to secure their being put in force by the civil power, and the sentence was pronounced at Chalcedon (451) that imperial laws that were contrary to canon law should be null and void. Freedom and religion were mutually supported because the Church, in which religion was incorporated, was at the same time the guardian of freedom. The power of the pope as Head of the Church Universal gained somewhat, but not sufficiently to affect in a very marked degree his influence as the Head of Christendom from the fact of his becoming a temporal prince during the eighth century. Again and again the popes have declared it was part of their duty to make and preserve peace on all sides; to mediate between royal families; to hinder wars or bring them to a speedy close; to defend Christendom against the incursions of the Mohammedans; to incite Christian nations to carry on the crusades for the recovery of the Holy Places of Jerusalem. Whoever felt himself oppressed turned to the Roman See, and, if it did not give him help, the pope was thought to have neglected his duty. "In an age", says Lingard, "when warlike gains alone were prized, Europe would have sunk into endless wars had not the popes striven unceasingly for the maintenance and restoration of peace. They rebuked the passions of princes, and checked their unreasonable pretensions; their position of common father of Christendom gave an authority to their words which could be claimed by no other mediator; and their legates spared neither journeys nor labour in reconciling the conflicting interests of courts, and in interposing between the swords of contending factions the olive-branch of peace" (History of England, IV, 72; quoted by Hergenröther). The great Protestant writer Grotius says: "Quot dissidia sanata sint auctoritate Romanæ Sedis, quoties oppressa innocentia ibi præesidium repent, non alium testem quam eundem Blondellum volo" (Hergenröther, "Church and State", pp. 286-7), i.e., how many quarrels were healed by the authority of the Roman See, how often oppressed innocence found support there, the same Blondel abundantly testifies.
Much misunderstanding as to the attitude of the popes has arisen from the Bull of Pope Alexander VI, when, acting at the solicitation of the sovereigns of Castile, he drew the limits of a line from the North to the South Pole, 100 Spanish leagues to the west of the most westerly island of the Azores; all that was east of the line belonged to Portugal, and all that was west of it to Spain. By this decision it has been said that the maxim "de externis non judicat ecclesia" has been violated, and also the further maxim that the conversion of subjects to the Catholic Faith takes nothing from the rights of infidel princes. The true explanation of this Bull will be found when it is remembered that the pope was acting as arbitrator between two nations of explorers, when it was most desirable that a line of demarcation should be drawn between the fields to be explored. It was intended only to prevent dissension and struggles likely to arise from rival pretensions, and, since by its terms it precluded any Christian prince from interfering within the boundaries assigned to each nation, it was a powerful preventive of wrong-doing. It being admitted that sovereignty over uncivilized peoples can be claimed under certain conditions by civilized nations, the pope sought only to regulate the rights of such nations so as to avoid war. It must be borne in mind, moreover, that the principal motive, as professed by the Spanish explorers, was not commerce or the acquisition of wealth alone, but the conversion of heathen nations to the Christian Faith.
It will appear from a review of the history of the centuries from the accession of Charlemagne to the crown of the Holy Roman Empire until modern times, the power of the pope as the supreme and common tribunal between nations has been exercised for the advantage of mankind in the extension of justice to all. In England, the excommunication of King John compelled the submission of a monarch, who, according to the Protestant writer Ward, had "by his violence and depravity drawn down upon himself the just detestation of mankind". In the example of Emperor Lothair of Lorraine in the ninth century, an instance may be found of an intervention of the pope to prevent the repudiation by this monarch of his lawful wife in order that he might marry another. The pope intervened to secure the release of Richard I of England from the prison, of the Duke of Austria and the emperor. By his interposition in 1193 he procured the liberty of the three daughters of King Tancred of Sicily; who had been unjustly carried off and retained captive by Emperor Henry VI. So in the case of the infant son of the King of Aragon. In 1214 Simon de Montfort was compelled to surrender his prisoner on the application of the prince's mother. Many other instances of equal importance show the reverence of peoples and sovereigns for the pope and for the fearless and impartial way in which his authority was exercised. The same author, from whom these instances have been quoted, speaks of the Councils of the Church. He says they were "composed of delegates from every nation of Christianity, and under this appearance Europe may fairly be said to deserve the appellation which has sometimes been bestowed upon it of a Republic of States." He points out that the two Councils of Lyons give an idea of "an almost perfect Court of Parliament of Christendom, in which the affairs of sovereigns were discussed, and sovereigns themselves proceeded against, under all the forms of a regular trial and sentence" (Ward, "Law of Nations", II, 55, 59).
The influence of the structure of the Roman State, with the emperor as the supreme ruler in temporal matters, educated the minds of the northern peoples, especially the Germans, who, on the fall of the Empire, gradually took possession of its former territory. After the acceptance of Christianity as the state religion in the reign of Constantine, it was not difficult for even the most ignorant of men to grasp an idea of the dual powers ruling human life — that of the sovereign with supreme jurisdiction in temporal matters, and that of the pope, the primate of all the bishops, the successor of St. Peter, the Head of the Church, the visible representative of the moral power of God on earth. While, in his human capacity, the pope in any given era may have been affected by the prevailing habit of thought of that era, and as a man has been subject to the limitations of our common nature, it may be safely said of the papacy that no institution has had so profound an effect upon the evolution of the laws of justice and right in the conduct of nations, and that without such a power of moral influence modern civilization would not have attained a higher plane than that of Imperial Rome. The sense of duty and obligation, which is a cardinal principle of Christianity, has been enforced among princes and peoples, so that even in our day the various nations, although to a great extent separated from the Catholic Faith, still recognize that the pope, as the head of the most venerable and most numerous body of professed Christians, embodies the moral power of Christianity and must be respected accordingly. As has been said by Hergenröther, "the perfection of international law depends upon two conditions:
Christendom and the Church have had a powerful influence upon both these conditions. After the fall of the Roman Empire it created amongst new States common interests and an international law, which, founded upon the principles and laws of the Church, was administered by her and her Head as an international tribunal under the protection of the penalty of the Church's ban" (Church and State, 369).
In giving an address at the conference held under the auspices of the Civic Federation in Washington on 18 Jan., 1910, Elihu Root, former Secretary of State of the United States, said: "Since the Congress of Vienna in 1815, in which the powers of Europe for the first time undertook to deal with subjects of general interest to them, as distinct from specific situations which were the results of war, up to three years ago there had been over one hundred and twenty congresses or conferences of representatives of a considerable part, practically the whole of the civilized powers of the earth, and those conferences or congresses have accomplished a great variety of things. They have established an international postal union; they have agreed upon and put into force rules for the protection of industrial property, patents, copyrights, and trademarks; they have established rules for sanitation or control, and, to some degree, the prevention of disease, under which each country binds itself to so legislate and so enforce its laws as to prevent its being a nuisance to the other countries with whom it is in conference. They have united in measures for the abolition of the slave trade, for the abolition of privateering, for the establishment of agreement upon rules of the private international law, so that private rights depending up on the laws of different countries may be recognized and dealt with under uniform rules; they have in a series of conferences held at Geneva established rules for the enforcement of humane principles for the conduct of war, and by rules adopted at The Hague, for the enforcement of humane rules in the conduct of war by sea; they have established for the greater part of the world uniform weights and measures; they have agreed upon rules designed for the prevention of the white slave trade; they have, by a series of conferences, agreed in Europe upon a number, as yet a comparatively small number, of provisions for the protection of labour; they have agreed upon rules for telegraphic communication, rules for the protection of ocean cables, rules for the government of wireless telegraphy."
It will be seen from the foregoing sketch that all these beneficent results have followed from the development of the Christian idea of the brotherhood of mankind. International law, like all other systems, will be found to be but an endeavour to bring into the affairs of life the eternal principles of right at all times taught by the Christian Church. For the actual status of the Holy See concerning conflicts and wars between Christian nations, peace, peace conferences, and international arbitration, see PAPACY; WAR.
HERGENRÖTHER, Catholic Church and Christian State (London, 1876); JAUGEY, Dict. Apologétique de la foi catholique (Paris, 1889), s.v. Alexandre VI; WARD, Law of Nations (London, 1795); KENT. Commentaries (1884); MANNING, International Law (London, 1875); DAVIS, The Elements of International Law (New York, 1908); WHEATON, International Law, ed. ATTAY (1904); LAWRENCE, International Law (1885); American and English Encyclop. of Law (1900); PERRIN, L'ordre international (Paris, 1888); PRADIER-FODÉRÉ. Traité de droit internation (Paris, 1885); The Peacemaker of the Nations in The Month (May, 1869); Speech of LORD STANLEY OF ALDERLEY in the House of Lords (25 July, 1887); letter (1870) of URQUHART to Pius IX in Acta Conc. Vaticani; in Coll. Lacensis, VII; HALLS, The Peace Conference at The Hague (New York, 1900), and critique of same by SHAHAN in Cath. Univ. Bulletin, VII (1901), 1-22.
APA citation. (1910). International Law. In The Catholic Encyclopedia. New York: Robert Appleton Company. http://www.newadvent.org/cathen/09073a.htm
MLA citation. "International Law." The Catholic Encyclopedia. Vol. 9. New York: Robert Appleton Company, 1910. <http://www.newadvent.org/cathen/09073a.htm>.
Transcription. This article was transcribed for New Advent by Douglas J. Potter. Dedicated to the Sacred Heart of Jesus Christ.
Ecclesiastical approbation. Nihil Obstat. October 1, 1910. Remy Lafort, Censor. Imprimatur. +John M. Farley, Archbishop of New York.
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