I believe rehabilitation is a 50/50 chance and it all depends on the offender choice to choose to leave behind the life of crime. It is quite obvious that it doesn't work on many people because most of them have not really dealt with what triggers them to commit crimes. The funny part is it is in human nature to be evil and good, we all battle with that dark side of us everyday till we are no longer tempted by it but for someone who takes pleasure in being evil it takes grace for such person to change.