The Discovery doctrine is a concept of public international law expounded by the United States Supreme Court. Under it, title to lands lay with the government whose subjects explored and occupied a territory whose inhabitants were not subjects of a European Christian monarch. The doctrine has been primarily used to support decisions invalidating or ignoring aboriginal possession of land in favor of colonial or post-colonial governments… The supposedly inferior character of native cultures was a reason for the doctrine having been used.
In 1452, Pope Nicholas V issued to King Alfonso V of Portugal the bull Romanus Pontifex, declaring war against all non-Christians throughout the world, and specifically sanctioning and promoting the conquest, colonization, and exploitation of non-Christian nations and their territories.
Under various theological and legal doctrines formulated during and after the Crusades, non-Christians were considered enemies of the Catholic faith and, as such, less than human. Accordingly, in the bull of 1452, Pope Nicholas directed King Alfonso to “capture, vanquish, and subdue the saracens, pagans, and other enemies of Christ,” to “put them into perpetual slavery,” and “to take all their possessions and property.” Acting on this papal privilege, Portugal continued to traffic in African slaves, and expanded its royal dominions by making “discoveries” along the western coast of Africa, claiming those lands as Portuguese territory.
Thus, when Columbus sailed west across the Sea of Darkness in 1492 – with the express understanding that he was authorized to “take possession” of any lands he “discovered” that were “not under the dominion of any Christian rulers” – he and the Spanish sovereigns of Aragon and Castile were following an already well-established tradition of “discovery” and conquest.
… it is important to recognize that the grim acts of genocide and conquest committed by Columbus and his men against the peaceful Native people of the Caribbean were sanctioned by the abovementioned documents of the Catholic Church. Indeed, these papal documents were frequently used by Christian European conquerors in the Americas to justify an incredibly brutal system of colonization – which dehumanized the indigenous people by regarding their territories as being “inhabited only by brute animals.”
In 1823, the Christian Doctrine of Discovery was quietly adopted into U.S. law by the Supreme Court. Chief Justice John Marshall observed that Christian European nations had assumed “ultimate dominion” over the lands of America during the Age of Discovery, and that – upon “discovery” – the Indians had lost “their rights to complete sovereignty, as independent nations,” and only retained a right of “occupancy” in their lands. In other words, Indians nations were subject to the ultimate authority of the first nation of Christendom to claim possession of a given region of Indian lands. According to Marshall, the United States – upon winning its independence in 1776 – became a successor nation to the right of “discovery” and acquired the power of “dominion” from Great Britain.
In other words, the Court affirmed that United States law was based on a fundamental rule of the “Law of Nations” – that it was permissible to virtually ignore the most basic rights of indigenous “heathens,” and to claim that the “unoccupied lands” of America rightfully belonged to discovering Christian European nations. Of course, it’s important to understand that (as Benjamin Munn Ziegler pointed out in The International Law of John Marshall) the term “unoccupied lands” referred to “the lands in America which, when discovered, were ‘occupied by Indians’ but ‘unoccupied’ by Christians.”