Final answer:
The issue of slavery caused sectional division and was influenced by judicial decisions, especially the Dred Scott Decision. Political parties evolved due to the tensions over slavery, notably with the rise of the Republican Party opposing its expansion. The Lincoln-Douglas debates further illuminated the country's divide on this contentious issue.
Step-by-step explanation:
The split over the issue of slavery intensified due to sectional division and judicial decisions. Political parties in the U.S. underwent change due to the movement to expand slavery. The Dred Scott Decision created further division over the issue of slavery. The Lincoln-Douglas debates brought much attention to the conflict over slavery.The national debate over slavery primarily revolved around its expansion into new territories. As the United States acquired more land, whether through war or purchase, the question of whether these new territories would be slave-holding or free became a polarizing issue. The political and judicial landscape of the 19th century was deeply affected by this discord. The Compromise of 1850 and the Kansas-Nebraska Act were examples of the legislative attempts to manage the growing tensions. The formation of the Republican Party, promoting the limitation of slavery to its current boundaries, was a direct response to the sectional strife.The controversial Dred Scott v. Sandford decision by the Supreme Court in 1857, which stated that slaves were not citizens and could not sue for their freedom while also asserting slave owners' rights to take their slaves into any territory, inflamed tensions further. Additionally, the famous Lincoln-Douglas debates in 1858, revolving around Senate seats, garnered national attention and highlighted the deep divisions between North and South over the issue of slavery. The resulting polarization contributed to the outbreak of the Civil War following Abraham Lincoln's election in 1860.