Who believed that neither congress nor local government had the authority to ban slavery from a territory?

The belief that neither Congress nor local governments had the authority to ban slavery from a territory was held by Chief Justice Roger B. Taney. This view was articulated in the landmark Supreme Court case Dred Scott v. Sandford in 1857, where Taney asserted that enslaved people were not citizens and that Congress could not prohibit slavery in the territories, effectively invalidating the Missouri Compromise. This decision intensified the national debate over slavery and contributed to the tensions leading up to the Civil War.