Okay, being inside a female human, connected by an umbilical cord and not breathing air are the features of a fetus.
Actually, the Dred Scott decision was logical if you start with the premise, as Judge Taney and others did, that slavery was legal. A
The ownership of all other portable tangible property remains the same when said property is moved. The Supreme Court was not ruling on the morality of slavery, it was ruling on the CONSTITUTIONALITY of slavery within the boundaries in which the Constitution applied.
Dred Scott only tried to gain his freedom when his former owner's wife refused to allow him to buy his freedom.
Scott and his wife could have simply refused to leave Wisconsin where they were living, but voluntarily returned to Missouri. His owner's widow wanted to rent him out after his owner died, but he did not want to be rented out. It was immoral to hold Scott in bondage, and illogical to do so, but it was constitutional.
The problem was that it meant that slaves fleeing the South would afterwards have to flee the country rather than simply the South: it made the Underground Railway more difficult.