It may be somewhat counterintuitive, but the impeachment of a witness is not the primary goal of cross-examination. The primary goal of cross-examination is to persuade the jury to endorse your case theory. Impeaching opposing witnesses contributes to proving your case theory only indirectly. It tends to encourage the finder-of-fact to reject the opposing side’s theory. It is especially true in the realm of criminal prosecution that this rejection of the opposition theory may or may not advance your case theory. If you are the prosecutor and the jury disbelieves your theory, it makes little difference whether they believe the defense theory. Thus, impeachment helps to build your case theory only in a negative way, by eliminating competition from the opposition’s theory.
Impeachment comes in three basic flavors:
2. incrimination, and
If you can demonstrate that the witness is saying something nonsensical, you have gone a long way toward impeaching the witness. In a horrific domestic violence case tried a few years ago, a man claimed that his wife had received her injuries by jumping from a moving car. He explained that she had been high on drugs and acting out in bizarre fashion for the past two weeks. The problem with his story, which was pointed out quite well on cross examination, was that he and his wife had just the previous night arrived in Florida on a commercial flight from Nevada. One fertile area of cross examination proved to be a line of questions on how his severely drug impaired wife got through the TSA screening to get on the plane. The defendant also had some difficulty explaining why, after his wife jumped from the moving car, he took her home, hogtied her, and stuffed her in a closet rather than taking her to the emergency room.
Incrimination, of course, means conviction of crime, but we use it here in a broader sense to mean any evidence of bad character. Indeed, in many jurisdictions across the nation impeachment by prior conviction has been so sanitized that it can have little effect on the witness’s credibility. In Florida, for example, the only questions that can be asked are:
Q: Have you ever been convicted of