Impeachment by Conviction of a Crime vs. Impeachment by a Bad Act

There are some similarities between impeaching someone by conviction of a crime and impeaching someone by a "bad act." In both, as in all types of impeachment, the goal is to call into question the credibility of a witness. This post will focus on the differences. 

A witness may be impeached by proof of a conviction of a crime; even if that conviction is pending appeal, it may still be allowable for impeachment purposes. But not all crimes are created equal. A straight-forward, general, rule is that any crime involving dishonesty or false statements will suffice for impeachment purposes. The court has no discretion to bar impeachment for these crimes. 

If a crime does not involve dishonesty, the rules change. Although a witness may be impeached by a felony that does not involve dishonesty, the court does have the discretion to disallow it. The court will balance the benefit and burdens of allowing impeachment, and will weigh more heavily towards not allowing it if the witness is a criminal defendant. A misdemeanor that does not involve dishonesty is simply not allowable for impeachment purposes. 

Generally, for all rules above, if more than 10 years have elapsed since the date of conviction or the date of release from confinement (whichever is later) the conviction is inadmissible for impeachment. I wouldn't, however, think of this as a bright-line rule. The court may admit an older conviction if its probative value substantially outweighs its prejudicial effect, and if the proponent gives the adverse party reasonable written notice of the intent to use it. That's a tough test to overcome, however, so mostly, these older crimes will not be allowable for impeachment. 

Worth noting, especially as a contrast to impeachment by a bad act, that extrinsic evidence is allowable here to prove the conviction. That's to say that this form of impeachment is not limited to cross examination of the witness. 

A question may appear testing how a pardon affects the above rules. A conviction cannot be used to impeach a witness if the conviction was subject to a pardon if the pardon was based on rehabilitation and if the witness has not been convicted of a subsequent felony. Likewise, it cannot be used if the pardon was based on innocence. 

Juvenile offenses are generally not admissible for impeachment. In a criminal case, however, a judge has the discretion to admit evidence of a juvenile offense committed by a witness other than the accused if the evidence would be admissible to attack the credibility of an adult and if the evidence is necessary to a determination of the accused's guilt or innocence. I don't see this rule tested often, but the test writers do sometimes pitch some curveballs. ⚾️

Next up is impeachment by prior bad acts. Key here is to realize that these are acts that do not amount to crimes but still might be relevant to the credibility of a witness. A witness may be impeached on cross examination with respect to an act of misconduct if the act is probative of truthfulness. The cross examiner must have a good faith belief that the witness committed the misconduct. 

Importantly, extrinsic evidence of such misconduct is not permitted. Stated otherwise, this type of impeachment is only allowable on cross examination. It's also important to understand that asking a witness about having been arrested for misconduct is not allowable, since an arrest does not itself amount to misconduct. Only the acts bearing on the misconduct can be inquired upon.