There's even an exception for it in the 13th amendment. Some slavery is still legal under the US constitution, as amended, which is probably a fun/easy bar bet

There's even an exception for it in the 13th amendment. Some slavery is still legal under the US constitution, as amended, which is probably a fun/easy bar bet to win. Not sure how the wider legal landscape treats this, especially whether other laws narrow the exemption to apply only to the "involuntary servitude" portion of the amendment, but if a state wanted to try to actually enslave people as punishments for crimes in the US they'd probably at least have a lively court case on their hands, and they might even win it, depending on how the rest of the laws are structured—the constitution alone wouldn't be enough to guarantee defeat.