Jurors’ Presumption of Innocence

21 Pages Posted: 2 Dec 2016 Last revised: 30 Apr 2018

See all articles by Nicholas Scurich

Nicholas Scurich

University of California, Irvine

Richard S. John

University of Southern California

Date Written: November 29, 2016


The 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.

Keywords: presumption of innocence, Bayes’ Theorem, jury decision making

Suggested Citation

Scurich, Nicholas and John, Richard S., Jurors’ Presumption of Innocence (November 29, 2016). Journal of Legal Studies, Forthcoming, UC Irvine School of Law Research Paper No. 2018-30, Available at SSRN: https://ssrn.com/abstract=2879009

Nicholas Scurich (Contact Author)

University of California, Irvine ( email )

Campus Drive
Irvine, CA 62697-3125
United States

Richard S. John

University of Southern California ( email )

2250 Alcazar Street
Los Angeles, CA 90089
United States

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