What principle allows people in a territory to make their own decisions regarding slavery?

The principle that allows people in a territory to make their own decisions regarding slavery is known as popular sovereignty. This concept emerged prominently in the mid-19th century as a means to determine whether new territories admitted to the United States would allow slavery. It rests on the idea that the authority of the government is created and sustained by the consent of its people, who have the right to decide on contentious issues, such as the legality of slavery, through a vote.

This approach was a key element of the Kansas-Nebraska Act of 1854, which allowed settlers in those territories to choose for themselves whether to permit slavery. This was seen as a way to balance the interests of free states and slave states while minimizing federal intervention in the issue. Ultimately, the reliance on popular sovereignty contributed to significant conflict and tension in the United States, leading up to the Civil War, as differing groups vied for control of these rights in newly formed territories.