Cowan, C. L., Thompson, W. C., & Ellsworth, P. C. (1984). The effects of death qualification on jurors’ predisposition to convict and on the quality of deliberation. Law and Human Behavior, 8, 53-79.
This study provides a straightforward test of the proposition that people who are permitted to serve on juries in capital cases (death-qualified jurors) are more likely to convict a defendant than are people who are excluded from serving on capital juries due to their unwillingness to impose the death penalty (excludable jurors). A sample of 288 subjects classified as death-qualified or excludable under the Witherspoon standard watched a 2½-hour videotape of a simulated homicide trial including the judge’s instructions, and gave an initial verdict. Death-qualified subjects were significantly more likely than excludable subjects to vote guilty, both on the initial ballot and after an hour’s deliberation in 12-person juries. Nine juries were composed entirely of death-qualified subjects (death-qualified juries), while 10 contained from 2 to 4 excludable subjects (mixed juries). On postdeliberation measures, with initial death-penalty attitudes controlled, subjects who had served on the mixed juries were generally more critical of the witnesses, less satisfied with their juries, and better able to remember the evidence than subjects from the death-qualified juries, suggesting that diversity may improve the vigor, thoroughness, and accuracy of the jury’s deliberations. No impact of jury composition (death-qualified vs. mixed); all juries hung. Death-qualified jurors more likely to vote guilty before and after deliberation. Forepersons tended to be male, sit at head of table, and claim experience; selection process brief and perfunctory. Half of juries used verdict-driven style; half used evidence-driven style. 47% of speaking acts concerned case facts, 32% concerned contested issues, and 21% concerned the law. Focus of discussion shifted from facts to law over time. Deliberation uncovered case facts but highlighted poor comprehension of instructions and correction of errors. Vote changes tended to occur after discussion of the law as opposed to case facts.