I have a friend who currently enjoys the "benefits" of our correctional system. He told of a new inmate, recently convicted of child molestation and rape, who joined their cellblock. Within a few hours, the "welcoming committee" left him bruised and bleeding, and, while being rescued by the guards, somehow managed to trip and fall headlong down a metal flight of stairs.
We might assume, by this account, that justice is served sometimes not with incarceration, but by being incarcerated.