You might see this in a motion, deposition notice, or trial prep email as a line about "materials for impeachment" or a warning that a witness "may be impeached." In that setting, it means challenging a witness's credibility - showing the judge or jury why some part of that person's testimony should not be fully believed. It does not mean removal from office. It usually involves pointing to a prior inconsistent statement, a contradiction in records, evidence of bias, or sometimes a qualifying prior conviction.

Practically, impeachment can change how a case feels in the room. A witness who sounds confident on direct examination can lose force quickly if medical notes, crash reports, text messages, or deposition answers tell a different story. That matters in injury cases, where disputes often turn on pain levels, how a collision happened, when symptoms started, or whether treatment was really related to the incident.

In Massachusetts, impeachment is governed largely by the Massachusetts Guide to Evidence (2024), including sections on credibility, prior inconsistent statements, bias, and certain criminal convictions. Strong impeachment can weaken a defense witness, but it can also hurt an injured plaintiff if records contain gaps or earlier statements do not match later testimony. Since Massachusetts generally has no cap on non-economic damages in most personal injury and auto cases, credibility can directly affect how much a claim is worth.