I have three questions for inquest, if he'd take them on, I'd be interested in his take on them. (1) What laws does the Supreme Court apply in federal territories and districts -- or do they have their own laws homegrown on territorial or district soil? (2) Does the Supreme Court rule on disputes between states, or on disputes between individuals in the states? That is, is the individual or the state standing before the court? (3) What was the majority opinion in Dredd Scott and is that good law?
2. SCOTUS has the power to hear controversies both between states and between citizens of different states. It also has the power to hear controversies between a state and a citizen of another state.
3. There were two main holdings in that case: One, that the due-process clause could be used to strike down actual laws (in this case the antislavery law in the territories), rather than methods of enforcing those laws. This illegitimate concept is what's known as "substantive due process", and it's been the germ of a whole field of judicial activism, including Roe vs Wade. The other holding was that black people couldn't be citizens, and there was no constitutional justification for that view.
I can't answer the first two, but I can respond to the third while you wait. Dred Scott was an escaped slave, and the majority opinion was that escaped slaves are property that must be returned to their owners.
The result of this decision, of course, was to further anger the Abolitionists, and eventually led to the freeing of the slaves in the Civil War.
But it raises some interesting question. You could say that the Constitution is neutral on the question of slavery. There were slaves at the time it was written, and they were not freed. The Founders deliberately failed to raise the issue. Probably they figured it would be a deal breaker if they did. But they wrote it in such a way that later interpreters could just as well say that "life, liberty, and the pursuit of happiness," and the word "person" in the Constitution, suggest that slavery was unconstitutional after all.
In the event, an amendment was passed specifically outlawing slavery, but some argue that it was not really necessary.
The present signicance of this question is that pro-lifers have suggested that the fetus is a person too. Liberal judges deny that. An opinion just the other day denied it, when a woman's fetus was killed. But in fact it is an interesting crux, and it may yet return some time in the future, much as the slavery issue did. Many have compared Roe v. Wade to Dredd Scott as the two worst decisions the court ever passed, and basically for the same reason: that they deny personhood to a class of human beings.