Francisco de Vitoria was born sometime around 1483 in Burgos. He studied philosophy and theology in Paris from 1507 to 1522 and returned to Spain in 1523. Three years later he obtained a chair as professor of theology at Salamanca and remained there until his death in 1546. None of his lectures nor anything else of his work was published during his lifetime, though he was an important advisor to the Spanish crown on public matters, including the divorce of Henry VIII and Spanish rights over the Indians of the Americas. But notes from his lectures were transcribed by devoted students, and in 1557, ten years after his death, the greatest part of his Relectiones—special lectures given by each professor annually—was published at Lyons. Two of these relectiones were of significant importance for the development of international law: the lecture on the American Indians (de Indis) and that on the law of war (de jure belli), both from 1539.
It is in some ways a misnomer to call Vitoria the father of international law”16 because he wrote in a period before the Peace of Augsburg, when an international society of princely states was just beginning to form. Perhaps “forefather” would be more apt. Certain ideas that do not seem to have been crucial to his thought—the change in the Gaian definition of ius gentium (the law of nations), the concept of totus orbis (a universal jurisdiction)—became crucial once a society had formed that could use these concepts. This accounts for the appearance (or illusion) of Vitoria's curiously modern ideas in the context of a rather conventionally Thomistic theology. Vitoria writes lucidly and provocatively of political communities that they are perfected when they can act independently of another political community, have their own laws, their own council, and their own bureaucracy (and thus may include pagan nations)—a very modern list of criteria for the legal recognition of states. At the same time, however, he makes the Church the arbiter of whether the conduct of a state is lawful, there being no society of states yet capable of making this judgment.
Verhoeven has written with insight that Vitoria's thought was structured by three facts: that it originated with issues arising from the discovery of America, that it was the work of a theologian-confessor, and that it had a single theme, war.17 These three facts “set the stage,” in Verhoeven's phrase, for the development of international law. This strikes me as pre-cisely right: writing before Augsburg, Vitoria could do no more than anticipate international law, set the stage, as it were, but the peculiar collection of subjects he dealt with prompted him to proffer rules that would provide a structure for further development once the society of states got underway, because he was called upon to write on issues of strategy (war) and law (the rights of Indians and the legal obligations owed to them), and the relation between the two.
Vitoria was occupied with the question of the extent to which Spain could claim the resources of the Indians and subjugate them. The Dominicans had tried to protect the Indians from exploitation. The Dominican priest Bartholomew de las Casas (1474 – 1566), a contemporary of Vitoria's, was the principal early evangelist among the Indians and lobbied ceaselessly for their humane treatment.18 Vitoria sought a solution in the doctrine of just war developed by the Dominican scholastic Thomas Aquinas. In order to apply this doctrine, Vitoria crafted an argument that, though in service to scholasticism, yielded elements we now regard as essential to international law. His argument had five steps.
First, Vitoria courageously rejected the claims of his king, Charles V, to global supremacy, 19 correctly observing that the political world was becoming one composed of separate princely states. Second, he shrewdly defined ius gentium (the law of nations) as the law inter omnes gentes (the law among all nations) as opposed to the construction provided by Gaius, whom Vitoria purported to be explicating, which held this law to be inter omnes homines (among all men). Third, thus armed, he was now able to bring Thomas Aquinas's doctrine of just war to bear on the problem, because this doctrine applied only among sovereigns, not among persons generally. Fourth, he associated natural law with the ius gentium, as Aquinas had held that the natural law was divinely inspired, in order that fifth, he might finally conclude that the Church was the ultimate arbiter of whether a war was just between two states. The Church, with its divine source of authority, would be the appropriate institution to apply international law (ius gentium).
Based on this argument, Vitoria could bring the Indians within the benign embrace of the Church by observing that they were distributed among states. As an almost inadvertent consequence, the fundamental ideas of a world composed of equal, separate sovereignties under law were laid out. Vitoria had expanded a law for a society (not an empire) composed of states (not princes).
Although Vitoria wished to treat the Indians humanely, his conclusions are hardly those of a humanist.20 While holding that Spain had no right to the property of the Indians, he nevertheless justified Spanish violence against them on the grounds that the Indians had no right to reject commerce, nor to impede the travel of the Spaniards wherever they might wish to go or to develop commerce. The Spanish freedom to join in activities undertaken by the natives, like the mining of gold, or tilling the earth, was “violated” if the natives did not permit such foreign participation and amounted to a kind of “banishment” which, as a punishment only justifiable in case of crime, was therefore the basis for a just war against them. This brought the conquistadores within the Thomist rule: “Unica est et sola iusta inferendi bellum, iniuria accepta.”21