Punishing a person rather than helping them improve themselves is the wrong way to go. While it may appease those who were victims of the crime, retribution does not actually accomplish anything. Rehabilitation however would cause the criminal to become more remorseful rather than hate filled and help them actually contribute to society someday.
Documented research has clearly proven that the inhuman treatment of criminals and the consequential demoralization of an already deficient self esteem level, most often produces a counterproductive effect, making them even more hardened and likely to repeat crimes. Rehabilitation does not work 100% of the time, that argument can be asserted with equally as much vigor, but to simply focus exclusively on the punitive aspects of crime has proven time and time again not to work in the best interest of society. Psychological research has shown that a personality disorder frequently is at the root of criminal thinking, with this disorder predominately based in a lack of self worth or personal value. People, who are given a sense of belonging or a feeling that someone actually cares about them and their future, stand the greatest chance of changing their behavior and becoming a viable member of society. It will not work all the time, but generating even the most modest of results is better than the punishment ideology our legal system currently employs.
When they go to jail for a crime they did they already have that mentality. So REHAB would not work because no matter what you do they still are likely to do t again when they get out. If they are in their for murder or they are just mentally unstable then we should not release them back in to society.