Popular sovereignty was the political doctrine that the people who lived in a region should determine for themselves the nature of their government. In U.S. history, it was applied particularly to the idea that settlers of federal territorial lands should decide the terms under which they would join the Union, primarily applied to the status as free or slave. The first proponent of the concept was Senator Lewis Cass of Michigan, who put the idea forward while opposing the Wilmot Proviso in 1846.
The concept was widely popularized by Stephen A. Douglas in 1854. Douglas, who coined the term, thought the settlers should vote on their status early in territorial development. Other supporters adopted a somewhat different stance, arguing that the status should be determined by a vote taken when the territory was fully prepared for statehood.
Popular sovereignty was invoked in the Compromise of 1850 and later in the Kansas-Nebraska Act (1854). The tragic events in â€œBleeding Kansasâ€� exposed the doctrine's shortcomings, as pro- and anti-slavery forces battled each other to effect the outcome they wished.
Popular sovereignty was first termed â€œsquatter sovereigntyâ€� by John C. Calhoun and that designation was adopted by its critics, which included proslavery Southerners and many New Englanders.
The hope by Douglas and other proponents of popular sovereignty that its application to new territories could preserve the union was soon dashed. It would only work if voters in a sufficient number of new territories could be persuaded to permit slavery, and it soon became apparent that apart from massive fraud, this end could not be achieved even in a border territory like Kansas.
When during the Lincoln-Douglas debates of 1858, Douglas conceded that local opposition to federal fugitive-slave laws could nullify them, it must have become clear to the South that popular sovereignty would not be an adequate vessel for their aspirations.