Discovery doctrine

The discovery doctrine, or doctrine of discovery, is a disputed interpretation of international law during the Age of Discovery, introduced into United States municipal law by the US Supreme Court Justice John Marshall in Johnson v. McIntosh (1823). In Marshall's formulation of the doctrine, discovery of territory previously unknown to Europeans gave the discovering nation title to that territory against all other European nations, and this title could be perfected by possession. A number of legal scholars have criticized Marshall's interpretation of the relevant international law. In recent decades, advocates for Indigenous rights have campaigned against the doctrine, which purportedly stemmed from some Papal bulls. In 2023, the Roman Curia of the Vatican formally repudiated the doctrine.

The means by which a state can acquire territory in international law are conquest, cession by agreement, occupation of land which belongs to no state (terra nullius), and prescription through the continuous exercise of sovereignty. Discovery of a territory creates a mere inchoate title which must be completed within a reasonable period by effective occupation of that territory.

Law professor Robert J. Miller states that by 1493, "The idea that the Doctrine [of discovery] granted European monarchs ownership rights in newly discovered lands and sovereign and commercial rights over Indigenous peoples due to first discovery by European Christians was now established international law, at least to Europeans." Law professor Kent McNeil, however, states, "it is not apparent that such a rule was ever part of the European law of nations."

Miller and others trace the doctrine of discovery back to papal bulls which authorized various European powers to conquer the lands of non-Christians. In 1452, Pope Nicholas V issued the bull Dum Diversas, which authorized King Afonso V of Portugal to "subjugate the Saracens and pagans and any other unbelievers and enemies of Christ", and "reduce their persons to perpetual servitude", to take their belongings, including land, "to convert them to you, and your use, and your successors the Kings of Portugal." In 1455, Pope Nicholas V issued Romanus Pontifex, which extended Portugal's authority to conquer the lands of infidels and pagans for "the salvation of all" in order to "pardon ... their souls". The document also granted Portugal a specific right to conquest in West Africa and to trade with Saracens and infidels in designated areas. Charles and Rah argue that these bulls were used to justify the Atlantic slave trade.

In 1493, following a dispute between Portugal and Spain over the discovery of non-Christian lands in the Americas, Pope Alexander VI issued the Bulls of Donation. The first of these, Inter caetera, drew a north-south line 100 leagues West of the Cape Verde Islands. It gave the Catholic Monarchs of Spain exclusive rights to travel and trade west of that line, and to "bring under your sway the said mainland and islands with their residents and inhabitants and to bring them to the Catholic faith." A second on the same day, Eximiae devotionis, referred to the rights of the sovereigns of Castile and León. These were extended later in the year by a third bull, Dudum siquidem. In 1494, Portugal and Spain signed the Treaty of Tordesillas, which moved the line separating their spheres of influence to 300 leagues west of the Cape Verde Islands. The treaty was eventually endorsed by Pope Julius II in the 1506 bull Ea quae pro bono pacis.

Throughout the sixteenth century, Spain and Portugal claimed that papal authority had given them exclusive rights of discovery, trade and conquest of non-Christian lands in their respective spheres of influence. These claims were challenged by theorists of natural law such as the Spanish theologians Domingo de Soto and Francisco di Vitoria. In 1539 Vitoria wrote that the Spanish discovery of the Americas provides "no support for possession of these lands, any more than it would if they had discovered us."

France and England also made claims to territories inhabited by non-Christians based on first discovery, but disputed the notion that papal bulls, or discovery by itself, could provide title over lands. In 1541, French plans to establish colonies in Canada drew protests from Spain. In response, France effectively repudiated the papal bulls and claims based on discovery without possession, the French king stating that "Popes hold spiritual jurisdiction, and it does not lie with them to distribute land amongst kings" and that "passing by and discovering with the eye was not taking possession."

Similarly, when in 1580 Spain protested to Elizabeth I about Francis Drake's violation of the Spanish sphere, the English queen replied that popes had no right to grant the world to princes, that she owed no allegiance to the Pope, and that mere symbolic gestures (such as erecting monuments or naming rivers) did not give property rights.