Answer:
Enslaved persons were unable to anticipate receiving assistance from the government at large or the legal system because they were not inhabitants of the United States, the U.S. Supreme Court said in this case. The ruling added that Congress lacked the power to outlaw slavery on federal property. (Dred Scott V. Sandford).
What if the U.S. Supreme Court had declared Dred Scott free?
Two of the states Scott had been in had precedent that once a slave was in a free state for some period of time, they became free. “this had been the holding in Louisiana state courts for more than 20 years” and “Missouri courts had previously heard over ten other cases in which they had freed slaves who had been taken into free territory”. The lower Missouri court, in fact, had ruled in favor of Scott: the Missouri Supreme Court had over-ruled them.
Suppose that the Supreme court would’ve affirmed the original lower court decision: Scott was free because he had spent long enough in free territory. This would’ve been, I think, a plausible result, perhaps even the expected result. Then what?
The Republican party weakens
The Dred Scott case galvanized the Republican party, as it led to (justified) fears that slavery would spread even to previously free states. Without this “lightning rod”, there would’ve been less support for Republicanism.
The Northern Democratic party strengthens
Conversely, the Northern Democrats (led by Douglas) had championed a compromise (“popular sovereignty”) under which territories could decide for themselves whether to allow slavery. This was torpedoed by the historical Dred Scott decision. Without this torpedo-ing, their compromise would’ve seemed more feasible.
In this scenario, I’ll posit that Lincoln still gets the 1860 nomination (he was seen as more moderate then Seward, and so given this less revved-up Republican party, he’s even more likely to win), and that the Democratic party still splits: if the Southern Democrats found the Union intolerable with a favorable Dred Scott ruling, they’d be even more upset now.
Let’s say that the Republican party is weakened enough, and the Northern Democrats strengthened enough, that Douglas becomes President - then what?
President Douglas
Douglas was pro-Union and anti-secession, saying:
- I am in favor of executing in good faith every clause and provision of the Constitution and protecting every right under it - and then hanging every man who takes up arms against it!
I think when the CSA fired on Fort Sumter, Douglas would’ve reacted as Lincoln did; the Civil War is “on”. However, Douglas died of typhus in June 1861, only 3 months after inauguration. The new President, stepping into a Civil War that was going badly for the North, would be the slave-owning ex-Governor of Georgia, Herschel Vespasian Johnson.
President Johnson (Herschel, that is)
Historically when Georgia seceded he became a CSA senator: let’s assume that in this counter-factual he stayed on as VP, and hence becomes president when Douglas dies.
Johnson was a moderate (he opposed secession) but no Lincoln (or Douglas for that matter). I’ll guess the result would’ve been a negotiated peace, perhaps as soon as after the first battle of Bull Run (July 1861) , and an independent CSA.