The discovery doctrine is a legal idea from long ago that says that when people found a new land, the people who found it had the right to own it. It was made a long time ago when people went around the world looking for new lands. When explorers found new lands, they sometimes claimed them for their country. This meant that their country got to make the rules about how the new lands would be used, and any people who were already living there had to obey. Some people do not like the discovery doctrine because it usually takes away the rights of the people who were already living on the land.