some will tell you that the US Federal Government outlawed slavery with the adoption of the 13th Amendment.
they are flagrantly lying to you. for the 13th Amendment itself tells you exactly how slavery may be practiced. here is the text of the 13th Amendment, in toto:
"Section 1. Neither slavery nor involuntary servitude, except
as a punishment for crime whereof the party shall have been duly
convicted, shall exist within the United States, or any place subject to
Section 2. Congress shall have power to enforce this article by appropriate legislation."
you notice the second clause in section 1? Slavery and Involuntary Servitude are both acceptable punishments for conviction of a crime. by Federal Law, neither Slavery nor Involuntary Servitude are considered "cruel" or "unusual" punishments.
of course, the 13th is one of the Reconstruction Amendments and is inadmissible as Law simply due to forced coercion of the Southern States ( invasion, murder, rape, theft from the Civil War and Reconstruction and withholding of their Rights as States until they subjugated themselves to the adoption of amendments to which not even all of the Northern States agreed ) to ratify these Amendments.
i just find it hilarious that even when you give the Yankees illegal Amendments to practice as Law they still can't get slavery banned. even though they lie and say they did.