What were some political defenses of slavery?

Political defenses of slavery usually revolved around the idea that the Northern states were powerless to stop the spread of slavery. As new territories were organized, the South argued that their inhabitants could not be constitutionally allowed to bar slavery within them. This position was given constitutional sanction in the Supreme Court's decision in Dred Scott v. Sandford (1857) that basically invalidated the Missouri Compromise, which had banned slavery in northern territories (but not southern ones). Southern politicians also argued that the Constitution protected the property rights of slaveholders. Since slaves were legally defined as property, the federal government had no authority to take them away from owners through emancipation. Finally, some people argued that slavery politically empowered ordinary white Southerners. These arguments should be seen as distinct from some of the moral "positive good" arguments offered by slavery supporters like politician John C. Calhoun and writer George Fitzhugh in the antebellum period.