Dred Scott was a slave born in Virginia who claimed he should have been emancipated when his owner had taken him to live in the free state of Illinois and the free territory of Wisconsin (now Minnesota). The court ruled that people of African descent held as slaves, and their descendants, whether they were free or slave, could never be U.S. citizens. The court also ruled that Congress had no right to prohibit slavery in the territories, and that slaves, not being citizens, could not sue in court. The worst decision in Supreme Court history? Most likely.