Seven years ago, in Roper v. Simmons, the U.S. Supreme Court recognized fundamental differences between children and adults that bear directly on the issue of culpability to outlaw imposition of the death penalty for any crime committed by a defendant younger than 18. Five years later, in Graham v. Florida, it relied on the same principles to ban life sentences without parole for juveniles convicted of non-homicide offenses. Next week, the Supreme Court will consider whether those principles must once again render a life-without-parole sentence unconstitutional for youth convicted of homicide offenses when it hears the cases of Kuntrell Jackson and Evan Miller, who were both sentenced to die in prison for crimes they committed when they were 14. Because there is no scientific, legal or practical reason to disregard the findings in Roper and Graham, the established constitutional law must prevail and life-without-parole sentences for all teenagers, including Jackson and Miller, must be prohibited as excessive. Life imprisonment without parole, which discounts any possibility for rehabilitation, is a severe sentence for any offender. For a teenager, it is an extraordinary punishment in both length and psychological severity.