[dragonwriter]

> Are you considering penitence to be a subset of rehabilitation? There's a reason they're called penitentiaries, after all.

That reason is because “penance” is, in ecclesiastical law, the earthly penalty for sin, and a “penitentiary” is a place dedicated to the experience of those consequences.

The connection to “penitence” (“the action of feeling sorry and regret for having done something wrong”) is more distant. (Also, the desire to cause penitence is more directly retribution, though it can be viewed as instrumental to rehabilitation.)