Thirty-five adults eligible for jury duty in California were used to test the hypothesis that people who are excluded from serving on juries in capital cases because of their opposition to the death penalty tend to place a greater value on the preservation of due process guarantees than on efficient crime control, and therefore are more likely to accept an insanity defense in criminal cases than are people who are permitted to serve on capital juries. Subjects who had previously been classified as death qualified or excludable read four summaries of cases in which the defendant entered a plea of insanity, and made judgments of guilt or innocence. In the two cases involving nonorganic disorders (schizophrenia), death-qualified subjects were significantly more likely than excludable subjects to vote for a guilty verdict. In the two cases involving organic disorders (mental retardation and psychomotor epilepsy), no differences existed between the two groups. In addition, excludable subjects gave significantly higher estimates than death-qualified subjects of the proportion of defendants pleading insanity who 'really are' insane. A bibliography, one reference note, and a list of 17 references are included. (Author abstract modified)