Dateline: November, 2007, Issue 4
Increasingly, judges are instructing criminal juries about presumption of innocence, burden of proof and reasonable doubt before presentation of evidence, rather than waiting until after the evidence has been presented. The timing of judicial instructions can have a significant impact on verdicts.
Kaplan and Wrightsman (1979) examined how the timing of judicial instructions affects jurors' verdicts in criminal cases. In their research, one group of jurors was given judicial instructions about presumption of innocence, burden of proof, and reasonable doubt before hearing the trial evidence. A second group of jurors heard these instructions after presentation of the same evidence. Jurors given judicial instructions before the trial evidence were less likely to find the defendant guilty than jurors instructed only after receiving the trial evidence.
Interestingly, the timing of the judicial instructions did not affect jurors' understanding of reasonable doubt. Jurors' required the same degree of conviction whether pre-instructed or post-instructed as to reasonable doubt. However, pre instruction on presumption of innocence and burden of proof lowered jurors' perceptions of culpability; jurors thought it was less likely the defendant committed the crime.
Pre-instruction of due process rights, particularly presumption of innocence and burden of proof, increases the likelihood of an acquittal.
Source Kaplan, S. M. & Wrightsman, L. S. (1979). On the requirements of proof: The timing of judicial instructions and mock juror verdicts. Journal of Personality and Social Psychology, 37, pp. 1877-1887.