Comprehending life and death matters: A preliminary study of California's capital penalty instructions.

Modern capital jurisprudence places special significance on judicial instructions to guide the discretion of the capital jury in reaching a penalty phase decision. Yet, previous social science research has raised doubts about the extent to which judicial instructions are generally understood by jurors and questioned their utility in producing intended effects. The present study measured the comprehension of the capital sentencing instruction employed in California. Data suggest widespread inability to define accurately the central concepts of aggravation and mitigation in use in virtually every state that currently has a death penalty statute, as well as the inability to distinguish properly the sentencing significance of the enumerated factors jurors are directed to use in reaching their life and death verdicts. In addition, an inordinate focus on the circumstances of the crime—to the exclusion of other potentially important factors—was identified, as well as special problems in comprehending the crucial concept of mitigation in constitutionally required ways.