Inadmissible Evidence, Impact on Juries

What is the impact on juror verdicts of inadmissible evidence that surfaces in the courtroom and of judicial instruction to disregard such information? This question has been addressed in laboratory research by attention to its two component parts. First, the research establishes that the presence of inadmissible evidence has a significant impact on juror verdicts in line with the evidentiary slant of the information: The level of guilty verdicts rises with pro-prosecution evidence and decreases with pro-acquittal evidence. Second, the research demonstrates that once inadmissible evidence is present, a corrective judicial admonition does not fully eliminate the impact of the inadmissible information.

These conclusions come from a 2006 metaanalysis that summarized 175 experimental tests, from 48 studies and 8,474 research participants. Confidence in the findings is ...