Since the southern states signed on to the constitution, that means they signed on to the clause that forbade corruption of the blood.
Asserting that a slave is a slave due to his mother being a slave is a form of corruption of the blood.
So the slaves that were born after the constitution should have all been free anyways.
1) The 'corruption of the blood' clause was there when the northern states signed it too, and they had no problem with the fact slavery was hereditary until a couple of decades later.
2) The 'corruption of the blood' clause was to prevent punishments from being handed down from one generation to the next. Slavery wasn't a punishment, it was legal condition.
3) The 'corruption of the blood' clause was for people, and slaves weren't considered 'people' by the Constitution.
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I see you haven't commented on the Priggs case or the Article 5 clause.
Why do you switch the subject instead of continuing the discussion?