As another pointed out, rehabilitation is pretty much a joke, (especially for the people stupidly incarcerated for minor drug offenses, then they get exposed to far worse behaviors); which just leaves punishment. And increasingly it seems, activist hippies on the far left don't seem to see much difference between justice/punishment and revenge, (typically in capital punishment cases), so this might be a future option.
What I mean by that remark: take the death penalty for example; if we execute a murderer, the counterargument goes that it makes us somehow just as bad as the murderer (despite the fact he's not an innocent like his victims were). Yet, if we lock up someone like Ariel Castro in a high security prison, (the guy who imprisoned several teenager girls in his basement and regularly raped them), you don't hear the same argument, though it's essentially the same logic, a case of doing to the perpetrator what he did to his victims, only the rape would come (ostensibly) from other inmates.
This may be a good compromise.