How did the Supreme Court's decision in the Dred Scott case lead to the decision of Southern states, including South Carolina, to secede? It was decided that slaves were citizens and had constitutional rights. This caused panic in the South and led to the immediate secession of Southern states. While the South was pleased that the decision affirmed slaves as " property" they feared that, once electedLincoln would reverse the decision and decided to secede. The court decided that Dred Scott was in fact free since he had lived in free territory , upsetting southern slave owners. The South immediately seceded. It created a new line across the country that designated a large free territory to the north and a small slave territory to the south. The South responded with secession.