In Western society, prison is viewed as a punishment- a "time-out" from society.
Although there are undoubtedly dangerous & broken people who may be beyond repair, many people are incarcerated for non-violent or drug offenses. The way our system is set up makes it difficult to become a well-adjusted citizen and re-enter the community once time is served.
If the focus was really on rehabilitation and education, it would make the tax dollars we spend on prisoners a better investment. Of course, one growing problem is the proliferation of "for-profit" private prisons. Just like corporations, the only thing that really matters is the bottom line. How much money can be squeezed from every person & situation is the guiding principle. The benefit to society and the individual is secondary, if it's even a consideration!
One proven way to help rehabilitate those in prison is practicing yoga, which has tangible benefits for both mind & body. The physical activity, combined with the art of self-control through breathing and physical discipline, goes a long way to changing the mindset of people who practice it.
I saw an article about this psychiatry study that demonstrated how yoga practice can reduce the psychological distresses of inmates- such as paranoia and anxiety.
The most important aspect is the positive effect it has toward re-introducing the person back into society. From the study: "The provision of opportunities for prison inmates to carry out physical activity in general and yoga exercise in particular can be an important tool for improving their reintegration into society and for helping them lead a drug free and law-abiding lifestyle upon release."
If we can get past the Puritan heritage in how we deal with people who break the law, and try to improve, rather than just punish, the individual, then it would solve many of the problems with our prison system and the people we place into it.
Here is a video I came across while researching the topic, of a project being carried out in Seattle called Yoga Behind Bars: