The Doctrine of Discovery is one of the earliest examples of classical international law—that is, the accepted legal norms and principles that control conduct between different states. The Doctrine was developed to regulate European countries’ actions and conflicts over exploration, trade, and colonization of non-European countries and was used to justify the domination of non-Christian, non-European peoples. The Doctrine was developed in Europe over several centuries primarily by the Catholic Church, Spain, Portugal, England, and the other colonial powers. There were two bases for the Doctrine: (1) the alleged authority of the Christian God and (2) the ethnocentric idea that Europeans had the power and the justification to claim the lands and rights of indigenous peoples around the world and to exercise dominion over them.
Scholars have traced the expansion of European rule and culture, and especially the Doctrine, to early medieval times, and in particular to the Crusades to recover the Holy Lands during the years 1096–1271. In addition to other justifications for the Crusades, the Church and various popes established the idea of a universal papal jurisdiction, which “vested a legal responsibility in the [P]ope to realize the vision of the universal Christian commonwealth.” This papal responsibility, along with the idea of a “just war,” offered support for Christian-led “holy wars” against infidels and was especially apparent in the Crusades.
In 1240, Pope Innocent IV, a canon lawyer, wrote a legal commentary on the rights of non-Christian peoples. His work influenced both the development of the Discovery Doctrine and the writings of Francisco de Vitoria and Hugo Grotius, famous sixteenth and seventeenth century legal theorists. In his commentary on a papal decree from 1209, Pope Innocent IV asked whether it was “licit to invade a land that infidels possess or which belongs to them?” Innocent ultimately answered “yes,” because such invasions were “just” wars, fought for the “defense” of Christians and for the re-conquest of Christian lands. In answering this question, Innocent focused on the authority of Christians to legitimately dispossess pagans of their dominium—their sovereignty, lordship, and property rights.
He conceded that pagans had some natural law rights and that Christians had to recognize the right of infidels to own property and govern themselves. Yet, he also held that the non-Christian’s natural law rights were qualified by the papacy’s divine mandate. Because the Pope was entrusted with the spiritual health of all humans, the Pope also had a voice in the secular affairs of all humans. Of course, a “pope can order infidels to admit preachers of the Gospel . . . [and if they do not] they sin and so they ought to be punished . . . and war may be declared against them by the Pope and not by anyone else.” Consequently, the Pope was duty-bound to intervene in the secular affairs of infidels if they violated natural law, as defined by Europeans, or if they prevented the preaching of the gospel.
In discussing the invasion of non-Christian countries to “defend” the faith, Pope Innocent IV borrowed from the writings of Saint Augustine, a fifth century scholar, and from earlier popes. Augustine had written that it was proper for Christians to re-conquer lands which had been seized by infidels. In addition, he claimed that Christians had the right to invade nations which practiced cannibalism, sodomy, idolatry, and human sacrifice, reasoning that such wars were a defense of Christianity, to “acquire peace,” and thus, were “work[s] of justice.” Pope Innocent IV also found support for holy wars in papal actions nearly two centuries earlier. Immediately preceding the official start of the Crusades, Archdeacon Hildebrand—later Pope Gregory VII, 1073–1085—negotiated a papal treaty with a French Count to fight a holy war against the Muslims in Spain.
Moreover, Pope Urban II, 1088–1099, granted Spanish crusaders the same papal indulgences that were granted for making pilgrimages to Jerusalem.47 Urban thereafter issued the first call for crusades to the holy lands in 1095, and he continued to link crusades with pilgrimages by granting indulgences for crusaders, just as he had done for participants in the holy war with the Moors. WILLIAMS, supra note 4, at 34–37. See generally ERDMANN, supra note 28, at 306–54 Poland’s position, however, was the same as Pope Innocent IV in 1240: infidels possessed the same natural law rights as Christians, and, therefore, their lands could only be invaded to punish violations of natural law and to facilitate the preaching of the gospel.54 The Council accepted Poland’s argument.55 Future crusades, discoveries, and conquests of heathens would have to proceed in accordance with the emerging legal standards of European Christianity.
The Council of Constance was called in 1414 to settle three major disputes, including the Knights’ claim to Lithuania. The Knights argued (1) that their territorial and jurisdictional claims could be traced to papal bulls from the Crusading era, which had authorized the complete confiscation of the property and sovereignty of non-Christians; and (2) that infidels lacked dominium and therefore were subject to Christian control. These standards supported the idea that pagans had natural rights, but that they also had to comply with European concepts of natural law or risk being conquered. Thus, the Council of Constance formally defined the Doctrine of Discovery. The Church, and secular Christian princes, had to respect the natural-law rights of pagans to own property and to govern themselves, but not if they strayed too far from European normative views.