For most purposes, the use of healthy prisoners as medical research subjects has stopped in this country. The reason is that a prisoner cannot freely consent to being a research subject. The situation is coercive by its nature. If prisoners are good research subjects for a particular experiment, they will assume that participating will bring favors from the jailers and refusing to participate will bring retribution. Research on prisoners is highly regulated by the Department of Health and Human Services. At the very least, prisoners should never be used as research subjects without careful appropriate institutional review board approval.