I agree that some can't be reformed. Usually you can tell by whether they are capable of feeling guilt or remorse. I definitely worked with some kids whose only remorse or guilt was related to whether they were CAUGHT or not. Others show genuine guilt and remorse for the effects of their actions. I think that's part of what you would evaluate in determining whether they should be released at a later age. The ones who were sociopathic were truly scary and sometimes ended up on our psych unit before they did anything that was actually criminal. After getting to know a kid, you could pretty much tell which way they were.
Kohlberg has clear phases of moral development which also can be looked at. This link describes them well. If someone gets stuck at 1 or 2, they probably won't rehabilitate.
Kohlberg's phases
Hybrid Mode
