Not sure what you’re saying in the first paragraph. In one respect you say he wasn’t tried as an adult when he was if I read correctly, and yet if he was tried as an adult, it seems you’re saying it wouldn’t or shouldn’t matter.
I tend to disagree that 15 is old enough. 15 is flatly a child. The brain is physiologically far from full development. That we whimsically throw aside our own laws on trying children or adults based on how vengeful we’re feeling on a given day astounds me.
The United States stands alone as the only nation that sentences people to life without parole for crimes committed before turning 18. This briefing paper reviews the Supreme Court precedents that limit the use of juvenile life without parole (JLWOP) and the challenges that remain to its abolition.