Examining jurors' ability to meet the constitutional requirement of narrowing in capital sentencing

The US Supreme Court has required that death penalty schemes narrow the class of persons eligible for a death sentence. Through the selection requirement, juries must use mitigating and aggravating evidence jointly to select the offenders engaged in the worst of the worst crimes. This study utilized between-subjects experimental design to test juror's ability to narrow directly. Utilizing the vignette approach, with brief descriptions of capital trials nested in self-administered questionnaires, we experimentally manipulated aggravating and mitigating evidence presented to mock jurors and examined their sentencing decisions in two independent samples. While mock jurors were able to identify offenders they considered to be engaged in serious crimes and offenders with diminished culpability, mitigating evidence and aggravating evidence did not interact and there was considerable inconsistency in the effects of mitigating evidence within and between samples. Implications for the constitutionality of the death penalty are considered.