To save the curious reader some Googling since the article doesn't seem to explain beyond "forced labor", one can be compelled to work under threat of solitary

To save the curious reader some Googling since the article doesn't seem to explain beyond "forced labor", one can be compelled to work under threat of solitary confinement at Angola so long as they are deemed medically able. Not quite full-on Chattel Slavery, it still is compensated and there is an "out," but that does seem borderline.