AbstractThe presumption of innocence explicitly forbids jurors from using official suspicion or indictment as evidence of guilt in a criminal trial. A behavioral experiment tested whether jurors follow this prescription. It revealed that, compared to when a suspect had been merely named, jurors thought that the individual was significantly more likely to be guilty after a detective referred the case to the district attorney and when he was formally charged and thus a criminal defendant. A judicial instruction to presume innocence reduced jurors’ beliefs in the defendant’s guilt. Regression analyses indicate that jurors’ prior beliefs predicted their posterior beliefs and further that their prior beliefs were predictive of verdicts even after accounting for their posterior beliefs. The findings suggest that jurors make different assumptions about the guilt of a criminal defendant before the introduction of evidence and that these assumptions influence their overall evaluation of the case and their verdict.