Before and After the Ruling: Roper v. Simmons (2005)

Some court decisions settle a question. Others change the entire framework through which the question is asked. Roper v. Simmons is the second kind. Before Roper, the United States was one of a small number of countries in the world that executed people for crimes committed as children. After Roper, it was not. What happened in between is one of the most important stories in the history of neurolaw.

Before the ruling

For most of American legal history, the age of a defendant at the time of a crime was treated as a mitigating factor in sentencing, something a judge or jury could consider, but not as a categorical bar to any particular punishment. A 16-year-old who committed murder could, depending on the state, be tried as an adult, convicted, and sentenced to death. In 1988, the Supreme Court drew one line. In Thompson v. Oklahoma, the Court ruled that executing someone for a crime committed at age 15 or younger constituted cruel and unusual punishment under the Eighth Amendment. [1] But the Court explicitly left open the question of defendants who were 16 or 17 at the time of their offense. In 1989, the Court addressed that question directly in Stanford v. Kentucky. The majority ruled that executing 16 and 17-year-olds did not violate the Eighth Amendment, finding that a national consensus against the practice had not yet emerged. [2] After Stanford, the execution of juvenile offenders was legal in the United States for crimes committed at age 16 or older. At the time Roper was decided, 72 people were on death row in the United States for crimes committed as juveniles. [3]

The neuroscience of adolescent brain development had been accumulating for years before Roper reached the Court. Researchers had documented through neuroimaging studies that the prefrontal cortex, the brain region responsible for impulse control, long-term planning, and consequence evaluation, continued developing well into a person's mid-twenties. Studies by Elizabeth Sowell and Jay Giedd using MRI technology showed that the adolescent brain was structurally and functionally different from the adult brain in ways directly relevant to decision-making and moral reasoning. [4] The American Psychological Association had submitted amicus briefs in earlier cases arguing that adolescents were categorically less culpable than adults due to these developmental differences. The science was clear. The law had not caught up.

The case

Christopher Simmons was 17 years old when he murdered Shirley Crook in Missouri in 1993. He was tried as an adult, convicted, and sentenced to death. His attorneys appealed, arguing that executing someone for a crime committed as a juvenile violated the Eighth Amendment's prohibition on cruel and unusual punishment. The Missouri Supreme Court agreed and overturned his death sentence, citing the evolving national consensus and the emerging neuroscience on adolescent brain development. The state of Missouri appealed to the United States Supreme Court.

After the ruling

In a 5-4 decision authored by Justice Anthony Kennedy, the Supreme Court ruled that the Eighth Amendment prohibits the execution of individuals for crimes committed before the age of 18. [5] The majority opinion did three things that had never been done together before in a Supreme Court decision. First, it conducted a systematic analysis of evolving standards of decency, counting the number of states that had abolished juvenile execution and concluding that a national consensus against the practice had emerged since Stanford v. Kentucky. Second, it cited scientific evidence about adolescent brain development explicitly, noting that juveniles have a lack of maturity and an underdeveloped sense of responsibility, are more vulnerable to negative influences and outside pressures, and that their characters are not as well-formed as those of adults. Third, it referenced international law and practice, noting that the overwhelming weight of international opinion was against juvenile execution. Justice Antonin Scalia wrote a sharp dissent, joined by Chief Justice Rehnquist and Justice Thomas, arguing that the majority had substituted its own moral preferences for the democratic judgments of state legislatures and that the use of neuroscience was inappropriate in a constitutional analysis. [5]

The 72 people on death row for crimes committed as juveniles had their sentences commuted immediately. No one convicted of a crime committed under age 18 could be executed in the United States.

Roper did not end the legal conversation. It opened a new one. If the brain is not fully developed at 17, what about 18? What about 20? What about 25? In Graham v. Florida (2010), the Court extended Roper's reasoning to ban life without parole sentences for juvenile offenders convicted of non-homicide offenses. [6] In Miller v. Alabama (2012), the Court went further, ruling that mandatory life without parole sentences for juvenile homicide offenders were unconstitutional, though it stopped short of categorically banning the sentence. [7] Each decision relied more heavily on neuroscience than the last. The prefrontal cortex, named explicitly in none of these opinions but present in all of them, had become a constitutional actor.

Beyond the courts, Roper accelerated legislative reform. States began raising the age at which juveniles could be tried as adults. Researchers began arguing for extending Roper's logic to young adults in their early 20s. The MacArthur Foundation launched its Research Network on Law and Neuroscience specifically to build the scientific foundation for further legal reform. [8]

The Roper line remains at 18. Despite neuroscience showing that brain development continues into the mid-twenties, no Supreme Court decision has extended categorical protection beyond juvenile status. Young adults aged 18 to 25 remain fully subject to adult sentencing, including life without parole and, in many states, the death penalty. The tension between scientific evidence and democratic lawmaking, between what the brain shows and what legislatures decide, remains unresolved and remains at the heart of every neurolaw debate.

The bottom line

Before Roper, the law treated age as a detail. After Roper, the law treated adolescence as a biological category with constitutional significance. That shift, from age as a mitigating factor to brain development as a constitutional limit, is the most important thing Roper did. It did not just change sentencing law. It changed what kind of evidence the law was willing to take seriously. That conversation is still happening. Mind on Trial is part of it.

If you want to go deeper: the full text of the Roper v. Simmons decision is available at oyez.org/cases/2004/03-633. The APA's amicus brief submitted in the case is available at apa.org/about/offices/ogc/amicus/roper.

Sources

[1] Thompson v. Oklahoma, 487 U.S. 815 (1988). oyez.org/cases/1987/86-6169

[2] Stanford v. Kentucky, 492 U.S. 361 (1989). oyez.org/cases/1988/87-6026

[3] Death Penalty Information Center. Juveniles and the Death Penalty. deathpenaltyinfo.org

[4] Giedd, J. N. (2004). Structural MRI of the Adolescent Brain. Annals of the New York Academy of Sciences, 1021, 77–85. pubmed.ncbi.nlm.nih.gov

[5] Roper v. Simmons, 543 U.S. 551 (2005). oyez.org/cases/2004/03-633

[6] Graham v. Florida, 560 U.S. 48 (2010). oyez.org/cases/2009/08-7412

[7] Miller v. Alabama, 567 U.S. 460 (2012). oyez.org/cases/2011/10-9646

[8] MacArthur Foundation Research Network on Law and Neuroscience. lawneuro.org