The Doctrine of Discovery is a principle in international law that was used to justify European colonization of non-European lands. According to this principle, when a nation "discovered" new land, it automatically gained rights and ownership over that land, even if it was already inhabited by other peoples. This doctrine ignored the fact that indigenous nations were already living on the land.
The authority for the Doctrine of Discovery was primarily granted by European monarchs and the Catholic Church during the period of European exploration and colonization. European monarchs, such as the kings and queens of Spain, Portugal, England, and other nations, issued charters, patents, and royal decrees that authorized their explorers to claim and colonize new territories. The Catholic Church, through papal bulls, also played a significant role in granting authority to European powers to claim lands that were not yet under Christian rule.