Revealing an omission of evidence, is an effective method to falsify your opposing witness credibility.

When preparing for cross-examination of a witness you should not only be concerned about what is in a statement, you should also look at omissions from the statement. If a witness testifies in relation to an important fact but neglects to refer to the fact in a pre-trial statement then it is open to suggest that the omission is because the fact did not exist. The purpose of this technique is to show that the new evidence, that was not mentioned before, is likely not accurate. This technique is effective because it leads to the conclusion that the omitted fact likely did not exist.

This technique of impeachment, based on an omission, is generally available except where an accused in a criminal case can rely upon the right to silence in dealing with the police. To be effective, the lawyer must do more than simply allege an omission. It would be important to set a foundation for the impeachment. The foundation would set out the fact that the witness knew the significance making the pre-trial statement and that they were trying to be completely accurate. Any relevant facts would be brought out that would tend to show that the omission would be unlikely. These facts might include the official nature of the pre-trial statement and the detailed nature of that pre-trial statement.

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