It's not just metaphorical slavery, it's literal. The Thirteenth Amendment allows for the enslavement of prisoners. > Neither slavery nor involuntary servitude

It's not just metaphorical slavery, it's literal. The Thirteenth Amendment allows for the enslavement of prisoners. > 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 their jurisdiction.