Opening Statements in a Jury Trial: The Effect of Promising More Than the Evidence Can Show

Previous research has indicated that attorneys' opening statements may have powerful effects on jurors' verdicts. However, since attorneys can never be certain of exactly how witnesses will testify, it may be unwise for them to make extensive opening statements and run the risk of promising more than the evidence can show; they may discredit their cases. An experiment was conducted to investigate the effects of those opening statements that make promises that are not fulfilled in evidence. Subjects read one of three different versions of a transcript of a simulated criminal trial: (1) the promise‐only version, in which the defense attorney promised evidence that would clearly indicate the defendant's innocence; (2) the promise‐reminder version, in which the same promise was made, followed by a reminder in the prosecuting attorney's closing argument drawing attention to the discrepancy between the promise and evidence; or (3) the non‐promise‐control version, in which neither the promise nor reminder was made. Although the promise led to less guilty verdicts than were found in the control condition, this effect was nullified by the prosecution's reminder. It was suggested that the defense attorney's promise affected the thematic frameworks that jurors used in interpreting the evidence in the case. Implications for trial practice were discussed.