Immature Minds in a “Maturing Society”: Roper v. Simmons at 20
Posted on Apr 30, 2025
In 2005, in Roper v. Simmons, the United States Supreme Court held that the “Eighth and Fourteenth Amendments forbid imposition of the death penalty on offenders who were under the age of eighteen when their crimes were committed.” The decision, after the execution of twenty-two people who committed crimes under the age of 18 during the modern death penalty era, marked the end of the juvenile death penalty in the United States.
In Roper, Justice Anthony Kennedy drew on state trends in the treatment of young people, scientific and medical studies, and the penological justifications underpinning capital punishment to support the Court’s decision that “today our society views juveniles … as categorically less culpable” than other defendants. In doing so, Justice Kennedy acknowledged the inherent arbitrariness in selecting an age cutoff: “The qualities that distinguish juveniles from adults do not disappear when an individual turns 18,” he wrote, “[h]owever, a line must be drawn.”
Twenty years later, the scientific, public policy, legal, and common-sense rationale that supported the Roper decision has become stronger in almost every respect — with one exception. The Roper Court said age 18 was “the point where society draws the line for many purposes between childhood and adulthood.” Today, a growing body of evidence now suggests that the line has been redrawn.
This report introduces new DPI analysis of the trends in sentencing and executions of defendants age 18 to 20 based on twenty years of data, from the time of the Roper decision on March 1, 2005 through the end of 2024.
Key Findings Top
New death sentences for 18- to 20-year-olds have diminished both in absolute terms and as a percentage of all new death sentences over the last twenty years. During the past five years, juries have sentenced just five such individuals to death.
Since the Roper decision, more than three-quarters of the death sentences given to 18- to 20-year-olds have been imposed on people of color.
Since Roper, people of color who are 18, 19 or 20 are twice as likely as white defendants in the same age range to be executed.
- Studies of brain development and juvenile behavior show that key factors cited by the Court in Roper (poor impulse control and unnecessary risk-taking) are not only present in adolescence, but also in 18‑, 19‑, and 20-year-olds.