You are mistaken. Slaves were chattel property, same status as cattle or livestock and thusly the institution was considered "covered" by Constitutional guarantees of private property ownership. Today, we view the slaves as though they were an equal human, but most Caucasians of that time did not. Simple color made them "not equal". Refer to the treatment of all peoples of color in that era for proof.
Your position is validated only from today's perspective interjected upon Nineteenth century life. It took a war to revise that old philosophy.
Show me one law that legally describes the condition of slavery?
It can't be done. There was no legal definition of slavery in the United States government until after the Civil war.
By The way, you have proved my point indirectly. Lincoln offered the South a legalization of slavery to force a national debate and a vote that they knew they would not and could not win.
Just like abortion and all those other things the democrats have forced upon us, slavery would never be legalized through normal means.
By no means. The "root cause" of a war can lie very deep indeed. "Root causes" are distinguished from surface causes. Historians who speak of slavery as a "root cause" of the war are trying to explain how it was that the US became divided into two hostile camps, rather than the specific circumstances that sparked the war.
Slaves were chattel property, same status as cattle or livestock and thusly the institution was considered "covered" by Constitutional guarantees of private property ownership.
There were abolitionists who argued that the Constitution and laws actually forbade slavery. That was to be sure very much a minority point of view.
The anarchist Lysander Spooner, beloved by neo-confederates for his attacks on Lincoln, wrote a book on the subject. It's a curiousity, since Spooner didn't believe that the Constitution was a binding authority, but if one values Spooner's contributions, his view on this should also be considered.
The larger point is that there wasn't one unified 19th century opinion on race and slavery. Even if there were it wouldn't be immune from criticism. If you criticize present day thinking about this or that issue, there's no reason why one can't do the same for past positions on social or political questions.
People at the time understood that, and that helps to explain why slaveowners were so terrified of the abolitionist movement.
Most interesting.