Dateline: December, 2007, Issue 3
Opening statements can be brief or extensive. Brief openings limit how much jurors learn about a given side's case. Extensive openings provide a much greater preview of a given side's case.
Pyszczynski and Wrightsman (1981) explored the persuasiveness of brief and extensive opening statements in a criminal case involved with transportation of a stolen vehicle across state lines. One group of jurors was given a brief prosecution opening followed by a brief defense opening. A second group of jurors was given the same brief prosecution opening, though followed by an extensive defense opening. Two other groups of jurors were presented an extensive prosecution opening followed by either a brief or an extensive defense opening.
The first side to offer an extensive opening most persuaded jurors.
When the prosecutor's opening was extensive, jurors typically thought the defendant was guilty after the opening statements and maintained this position throughout the rest of the trial. If the defense responded with an extensive opening of its own, guilty verdicts increased.
When the prosecutor's opening was brief, an extensive defense opening led jurors to favor acquittal after the openings, a position jurors maintained throughout the rest of the trial. When jurors heard a brief prosecution opening followed by a brief defense opening, they initially favored acquittal, but changed their position after the first prosecution witness and continued to return guilty verdicts thereafter.
Said differently, jurors find defendants guilty when the defense opening is brief. Using an extensive opening helps the defense if the prosecution's opening is brief, and hurts the defense if the prosecution's opening is extensive.
In sum, the prosecution has an advantage if it chooses to use it. The first extensive opening has the most influence on jurors. A brief reply to an extensive prosecution opening does not help the defense, and an extensive reply hurts the defense. If the prosecution fails to take advantage (i.e., gives a brief opening), an extensive defense opening is in the defense's best interest.
Source Pyszczynski, T. A., & Wrightsman, L. S. (1981). The effects of opening statements on mock jurors' verdicts in a simulated criminal trial. Journal of Applied Social Psychology, 11, pp. 301-313.