When can a witness's prior convictions not be used?

The ability to use a witness's prior convictions in court primarily hinges on rules concerning relevance and credibility. In the context of rehabilitation after impeachment for lack of truthfulness, prior convictions cannot be introduced to enhance a witness's credibility once their truthfulness has already been questioned. The purpose of rehabilitation is to restore a witness's credibility, which is generally not achieved by drawing attention to their previous misconduct or convictions.

In contrast, other factors that might bar the use of prior convictions—such as expungement, irrelevance, or the timing of their introduction—do not capture the nuanced rules surrounding impeachment and rehabilitation effectively. For example, a conviction that has been expunged typically cannot be mentioned, but that does not pertain directly to the context of rehabilitation. Similarly, while relevance is a crucial factor for admissibility, the specific procedural norms surrounding rehabilitative efforts after impeachment distinctly highlight the inappropriateness of utilizing past convictions in that scenario.