At the time, they did not violate the constitution, in fact one could argue that the constitution at least condoned slavery.
Yes they did
Did the Constitution ever specifically deny citizenship to African-Americans ?
Does not the Constitution talk about equality ?
Does the Constitution say who does and who does not benefit from the rights expressed in the BoR ?
From the document itself:
"Representatives and direct Taxes shall be apportioned among the several States which may be included within this Union, according to their respective Numbers, which shall be determined by adding to the whole Number of free Persons, including those bound to Service for a Term of Years, and excluding Indians not taxed, three fifths of all other Persons"
So a slave had no right to a trial, no right to free speech, no right to bear arms, no right not to self incriminate or be free from unwarranted searches ?
The Constitution can't have it both ways
We all know that the founders were largely a bunch of slave owning racists, but the can't speak of freedom and justice for all in the same breath as the sign the document that starts "WE THE PEOPLE..."
Gun laws violate the constitution, but you don't have any issue with them for some reason.
No they don't and those that did have been struck down by the courts
Anyway, as you have acknowledged, government produced law is often immoral, and no one has any obligation to obey an immoral government law.
But declaring a law to be immoral is not a get-out-of-jail-free card for anyone to cherry pick which laws to obey
You must demonstrate that a particular law is immoral
A slave isn't legally authorized to run away, yet you have agreed that he should run away.
That would be their decision, but one I would support should they chose to do so
But again, it would be in line with the Constitution - the highest law in the land
You can't have it both ways. Either we are obligated to obey the government, or we should do what we think is right. So which is it?
You obey the law
Should you decide one is immoral, you should be at liberty to challenge it
In the scenario I presented, the vigilante didn't do anything morally wrong. So why should he be punished?
Absolutely he did something wrong
He should be punished because what he did was legally, and morally wrong
No-one should be judge, jury and executioner - everyone deserves the benefit of due process and the best legal defense possible
It's what marks out out as different from savages
We can ONLY justify punishing anybody by the law and adherence to it. Without the law, we have no justification to punish anyone
Even if I agreed with this absurd "argument", there is overwhelming evidence that government-run courts are simply terrible when it comes to producing just decisions. I could give you case after case after case of wealthy or politically connected individuals being treated with extreme leniency, and case after case of poor people being handed harsh prison sentences for (relatively) trivial crimes.
So what ?
Are you justifying vigilante justice because it's more evenly balanced than the courts ?
The legal system of the USA is broken, so let's form a lynch mob and just hand them ?
Or in the case of last Wednesday, let's just kill the politicians we don't like and crown one we do.
For what it's worth I've discussed ways to fix the US criminal justice system. Getting rid of juries would be a good start IMO.