The history of the Catholic Church with respect to aboriginal people in North America has been mixed. Michael Stogre, the Canadian Jesuit wrote a good book entitled "That the World May Believe" on the history of papal social thought on indigenous people. Stogre argues that as interpreters of natural law, the Catholic Church did hold that indigenous people did have natural dominion to the land and therefore could not legally be enslaved. I will have to reread the book to see how right to the land figured in this. Afterall, indigenous people were dispossessed of their original lands and the legal recourse that native people are seeking here in Canada is integrally connected to the history of European colonization. The Catholic Church was heavily involved in the colonial project of the European nations most notably through residential schools.
Additionally, we need to understand that the colonization of North America by Europe involved primarily three different countries; Britain. France and Spain. Each country had a different approach to assimilation and subjugation. Spain was the most draconian. Bartolomé de Las Casas is an important Dominican human rights activist who was very instrumental in the fifteenth century criticizing the manner in which Spain treated the indigenous people. I am sure he would be pleased with this symbolic development some 500 years later.