In 2003, the Missouri Supreme Court set aside the death sentence of Christopher Simmons, who was 17 when he was arrested for the murder of Shirley Crook. The Simmons court held that the "evolving standards of decency" embodied in the Eighth Amendment's prohibition of cruel and unusual punishments barred execution of persons who committed capital crimes before their 18th birthday. This decision was based in part on the emerging legislative consensus in the states opposing execution of juvenile offenders and the infrequency with which the death penalty is imposed on juvenile offenders. The State sought a writ of certiorari, and the case is now before the U.S. Supreme Court.
This project analyzed patterns of death sentences for adolescent homicide offenders in state courts in the U.S. from 1990-2004. Since 1994, when death sentences for juvenile offenders peaked, juvenile death sentences declined significantly, and at a greater rate than would be expected from declines in homicides. In particular, the decline in juvenile death sentences since 1999 is statistically significant after controlling for the murder rate, the juvenile homicide arrest rate, and the rate of adult death sentences. This downward trend in juvenile death sentences signals that there is an evolving standard in state trial courts opposing the imposition of death sentences on minors who commit capital offenses.
We also examined the effects of the growing number of innocence cases on the declining rates of juvenile death sentences. We found no evidence that the cumulative number of innocence cases generally across the nation influences the rate of juvenile death sentences. However, we showed that the combined effects of recent capital innocence cases both within juvenile death sentencing states and across the nation exerted a downward pressure on rates of juvenile death sentences. We concluded that capital innocence cases have contributed to the reluctance of juries to impose death sentences on juveniles, and may have influenced the evolving social and legal norms opposing the use of the juvenile death sentences that we observed after the watershed year of 1999