Actually the slave states all had laws that regulated the treatment of slaves. Slaves did, in fact, have some standing under the laws in all the slave states.
Unborn humans on the other hand have no standing at all as Roe declared that they are not "persons" and therefore have no legal rights.
I object to the use of the term "slave states." They were "choice states" - people could CHOOSE whether to own slaves or not in those states.
(sarcasm off now)
I see several similarities between the anti-abortion struggle and the abolition and civil rights movements.
The phrase "you can't legislate morality" was coined by segregationists opposing Dr King and his allies.
I have posted elswhere here, recently, on abortion. No need to repeat my views in detail. :)