1537 - Pope Paul III forbids slavery of indigenous peoples in the Americas in the encyclical Sublimis Deus

Pope Paul III forbids slavery of the indigenous peoples of the Americas and any other population to be discovered, establishing their right to freedom and property (Sublimis Deus).

Pope Paul III, the fourth pope during the period of the Protestant Reformation, became the first pope to take active reform measures in response to Protestantism. Soon after his elevation, 2 June 1536, Paul III summoned a general council to meet at Mantua in the following May; but the opposition of the Protestant princes and the refusal of the Duke of Mantua to assume the responsibility of maintaining order frustrated the project. Paul III first deferred for a year and then discarded the whole project.

In 1536, Paul III invited nine eminent prelates, distinguished by learning and piety alike, to act in committee and to report on the reformation and rebuilding of the Church. In 1537 they turned in their celebrated Consilium de emendenda ecclesia, exposing gross abuses in the Curia, in the church administration and public worship; and proffering many a bold and earnest word on behalf of abolishing such abuses. This report was printed not only at Rome, but at Strasbourg and elsewhere.

But to the Protestants it seemed far from thorough; Martin Luther had his edition (1538) prefaced with a vignette showing the cardinals cleaning the Augean stable of the Roman Church with foxtails instead of brooms. Yet the Pope was in earnest when he took up the problem of reform.

In May–June 1537 Paul issued three documents: the bulls Sublimus Dei (also known as Unigenitus and Veritas ipsa); Altituda divini consolii; and Pastorale officium, the brief for the execution of Sublimus Dei.

"Altituda divini consolii" was essentially a bull to settle a difference between the Franciscans and Dominicans over baptism, but "Sublimus Dei" is described by Prein (2008) as the "Magna Carta" for the human rights of the indigenous peoples of the Americas in its declaration that "the Indians were human beings and they were not to be robbed of their freedom or possessions".

Sublimis Deus (The sublime God) was promulgated by Pope Paul III on June 2, 1537,  forbidding the enslavement of the indigenous peoples of the Americas (called Indians of the West and the South) and all other people. It went further to state that the Indians were fully rational human beings and had rights to freedom and private property, even if they were heathen It strengthened the recent decree issued by Charles V of Spain in 1530 in which the King prohibited the enslavement of Indians. Another related document was the ecclesiastical letter Pastorale Officium, issued May 29, 1537, and usually seen as a companion document to Sublimis Deus.

In Sublimis Deus, Paul III unequivocally declares the indigenous peoples of the Americas to be rational beings with souls, denouncing any idea to the contrary as directly inspired by the "enemy of the human race" (Satan). He goes on to condemn their reduction to slavery in the strongest terms, declaring it null and void for any people known as well as any that could be discovered in the future, entitles their right to liberty and property, and concludes with a call for their evangelization.

The bull had a strong impact on the Valladolid debate, and its principles eventually became the official position of Charles V, Holy Roman Emperor and King of Spain, although it was often ignored by the colonists and conquistadores themselves. 

The reality of colonial power and exploitation was restored with the executing brief for the bull ("Pastorale Officium") being annulled by Paul in 1537 at the request of the Spanish who had rescinded the decree previously issued by Charles. 

The bull is cited at times as evidence of a strong condemnation by the church of slavery in general, but some scholars point out that Paul sanctioned slavery elsewhere after the issuing of Sublimis Deus.