The Bible, OT & NT, certainty doesn't prohibit the most basic of human civil rights, freedom from slavery. Of course, the Bible was used to justify the ownership of slaves in America, as in many other lands.
An often-forgotten footnote in the history of America is that there was a time when poor white Irish were imported from Ireland to be sold as slaves during the 17th and 18th century. In fact, their worth was considered even lower than that of black slaves, who often fetched a price 10x that of an Irish slave!
Market forces being what they are, some slave owners engaged in breeding "designer slaves", when black "studs" were mated with Irish women to create offspring that fetched a higher price (as mulattos).
http://www.globalresearch.ca/index.php?context=va&aid=31076
I share this, as you may encounter some who do not recognize the intrinsic evil of a certain practice (such as slavery; they may even try to argue to DEFEND the Bible's stance), until they consider that it may have happened to THEIR ancestors.
Many racists will find the thought of a black man "defiling" a white women as abhorrent; this tends to make those harboring racist mind-sets to re-evaluate which of their cherished beliefs they wish to protect: their racism, or their Bible (which condones slavery, including such things as above). They cannot have both.