What is impeachment by bias designed to show?

• A. A witness's credibility is compromised by personal or monetary interest.
• B. A witness lied about a prior statement.
• C. A witness's memory failed.
• D. A witness has no expertise.

Answer: (A)

Impeachment by bias is about showing that a witness’s credibility may be compromised because they have a personal or financial stake in the case. If someone stands to gain financially, has a close relationship with a party, or has some motive to benefit one side, their testimony may be colored by that interest, so jurors should treat the testimony with added skepticism regarding reliability.

This is distinct from other impeachment grounds. For example, lying about a prior statement targets truthfulness on a specific past assertion, not a general susceptibility to bias. A memory failure speaks to recall ability, not to motive or interest. A lack of expertise concerns qualification to testify or the weight given to their opinion, not bias in credibility.