It's a concept I created, which means nobody gives a crap about it except me, but here it is:
At whatever age someone 20 or under commits a normal life-sentence crime (say 16), they would spend a maximum 16 years away from society, with rehabilitation and re-integration into society the goals. I know at age 60 I would hate to be held accountable for anything - and I mean anything - I did as a teenager.