State of Arizona, Appellee v. Shawn Ryan Grell, Appellant

Summary

The court independently reviewed the capital sentence and found that Grell proved by a preponderance of the evidence that he had mental retardation, based on significantly subaverage intellectual functioning, significant adaptive deficits, and onset before age eighteen. Because executing a person with mental retardation is constitutionally prohibited, the court vacated the death sentence and imposed natural life imprisonment. Bales, Vice Chief Justice, concurred while noting unresolved procedural questions for later cases concerning how mental-retardation claims should be considered after the statutory pretrial determination.