A study of jury decisionmaking conducted at the University of Chicago explored how sane behavior is differentiated by jurors from insane behavior, how the testimony of expert witnesses is evaluated by jurors, and how juror instructions are interpreted. Study results indicate that jurors comprehend and remember instructions and that jury instructions do not produce different verdicts. Other studies show that when jurors get a chance to express their recommendations about what should happen to a defendant, they make very different suggestions for each case. Juror discriminations among cases do not coincide with the organic versus psychogenic distinction of mental illness in the insanity defense. Further, psychiatric sentencing is relatively complicated for jurors, and most prefer to let a doctor decide. Research does not support the belief that jurors will reach a not guilty by reason of insanity verdict because they have a natural tendency to do so. Research does show, however, that it is possible to infer some errors and stereotypes that jurors have regarding insanity. For guilty-prone jurors, there is the belief that a crime against property rather than persons indicates sanity. Another error that can be inferred from guilty-prone juror comments is that manipulation and cleverness are not associated with insane persons. Evidence indicates that sentiments, biases, and extralegal concerns affect juror decisions in some cases. It is concluded that the perspective of ordinary citizens needs to be included in the debate over insanity tests. This perspective can serve as a sound moral base for insanity, since jurors serve as the conscience of the community.