Final answer:
Supreme Court rulings have determined that juveniles cannot receive mandatory life sentences without parole for homicide (Miller v. Alabama), and no life sentences without parole for non-homicide offenses (Graham v. Florida). Additionally, juveniles cannot be sentenced to death (Roper v. Simmons).
Step-by-step explanation:
The Supreme Court's decisions concerning the sentencing of juvenile offenders have significantly shaped legal precedent. In the case of Miller v. Alabama, the Court ruled that a sentence of life imprisonment without the possibility of parole cannot be a mandatory sentence for juvenile offenders found guilty of homicide. Similarly, in Graham v. Florida, it was determined that juveniles who commit non-homicide offenses cannot be sentenced to life imprisonment without parole. Furthermore, according to Roper v. Simmons, the death penalty cannot be imposed on those who were under 18 at the time they committed the crime.