In Canada, our prison system has a type of forced labor which the prisoners are not paid, the equipment is unsafe and has caused potentially life threatening injuries not limited to loss of limbs. "Workers" are often pushed to work, even when sick, and not working encompases harsh punishment such as being locked in a cell for 6 months straight without blankets, and lesser food rations. The supplies produced are for profit, such as License Plates, park benches, etc (ref: http://www.mcscs.jus.gov.on.ca/english/corr_serv/adult_off/OffenderProgramsServices/treat_prog_trilcor/treat_prog_trilcor.html ), and is justified as legitimate "correction" for inmates.
Strictly philosophical, could such a system be considered slavery ?
I can draw a lot of parallels to America's not so distant past where such "abuse" of power led to the enslavement of millions and was commonly accepted as those people were considered (at the time) to be sub-human.