These cases can all very well come down to one question. Is prison used to make us safer, or is it used to punish? A teen that murders for fun is likely to turn into an adult that murders for fun. So from a prevention stand point you could justify putting a teen in jail and locking the key. However, that would mean that courts should be looking at something besides the nature of the crime, and instead look at how likely a repeat offense is. If your looking at strictly punishment, then its pointless, after about 5 years or so it ceases to be punishment it simply becomes life for the person in prison. Research has shown this to be the case, can you trust the research? Who knows. So really from a strictly punishment stand point anything over five years is a waste. Now you could argue peace of mind for the wronged individual or that individuals family in the case of murder, or for the sake of the community, they feel safer, and possible future criminals might not want to spend the rest of their life in jail. (hey even if its just one its worth it right) Really though the single easiest justification for long term sentences or even the death penalty is this: Risk of future maltreatment of others. This is the details ignored by others, did this teenager do something that he is likely to repeat? If he was a serial killer, gang banger or rapist, then chances are yes, he would go back to a similar crime pattern. Therefore there is justification for keeping him in jail forever. Statistics show that this is simply fact, reform is unlikely for these individuals, something in the way their mind works makes them prone to murder. If he killed a cheating girlfriend, beat someone to deat in a bar fight, or something of that nature, the likelyhood of a repeat offense is much smaller, and therefore perhaps the sentence should be much lighter. However any sexual assault offense, or pattern of violent, homicidal behavior cannot be ignored, if you can demonstrate a pattern or violent homicidal behavior or rape that person should be held in jail forever, there is little to no hope for reform. Its just fact.