Legal Definitions - impeachment of a witness

Impeachment of a Witness

In a legal trial, impeachment of a witness refers to the process of challenging or undermining the credibility and trustworthiness of a witness's testimony. An attorney uses this strategy to cast doubt on whether the jury or judge should believe what the witness is saying. This is typically done by presenting evidence or asking questions that reveal inconsistencies, biases, or falsehoods in the witness's statements, or that contradict their testimony.

Here are some examples of how a witness might be impeached:

• Prior Inconsistent Statement: Imagine a witness testifies in court that they saw a blue car speed away from an accident scene. During cross-examination, the opposing attorney presents a copy of a police report where the same witness stated immediately after the accident that they saw a green car. This prior inconsistent statement is used to impeach the witness, suggesting their current testimony might not be accurate because they have given conflicting accounts.
• Bias or Motive to Lie: Consider a witness who testifies that their business partner, who is the defendant in a fraud case, is an honest and trustworthy individual. The prosecution might then reveal that the witness stands to lose a significant amount of money if their business partner is convicted, suggesting they have a strong financial motive to provide favorable testimony for the defendant. This revelation of bias aims to impeach the witness by showing their testimony might not be objective.
• Contradiction by Other Evidence: Suppose a witness claims they were at a specific location at 8:00 PM on a particular evening and saw a key event unfold. The opposing attorney could then introduce a time-stamped receipt or security camera footage showing the witness making a purchase at a store several miles away at 7:55 PM on that same evening. This direct contradiction by other evidence impeaches the witness by demonstrating that their account of being at the scene at 8:00 PM is impossible, thereby undermining the reliability of their entire testimony.