Which method is NOT used for impeaching a witness's testimony?

Proving consistency with prior statements is not a method used for impeaching a witness's testimony because impeachment focuses on showing that a witness's testimony is unreliable or untrustworthy. Impeachment seeks to establish reasons to doubt the credibility of a witness, and presenting consistent prior statements would actually help reinforce the witness's reliability rather than undermine it.

In contrast, presenting evidence of witness bias can highlight potential motivations for a witness to distort their testimony, thereby suggesting they may not be truthful. Revealing a witness's criminal history can also be a tactic to challenge their character and credibility. Questioning a witness's demeanor, such as observing inconsistencies in their behavior or body language while testifying, can similarly raise doubts about their honesty or reliability. These methods are targeted toward casting suspicion on the testimony provided, distinguishing them from the idea of proving consistency, which would bolster a witness's credibility.