What Is Impeachment Evidence?

In criminal cases, lawyers use various types of evidence to question the accuracy of witnesses’ testimony. The process is called impeachment. Various different kinds of impeachment evidence may show that a witness is not being truthful, such as if prior statements to the police contradict testimony on the stand, or that a witness was not able to observe what happened, such as if the witness has poor vision.

Oklahoma law permits lawyers to use specific types of evidence for impeachment purposes. Lawyers may question the witness they are trying to impeach, or they may question a different person to impeach a witness. Impeachment evidence, including testimony and documents shown to witnesses, may be very different from the evidence used to show that the defendant did not commit a crime. For example, lawyers may seek or use the following kinds of impeachment evidence:

• testimony about the witness’s reputation for having a character for truthfulness or untruthfulness
• testimony about a witness’s opinion about having a character for truthfulness or untruthfulness
• evidence of certain, specific types of criminal convictions
• prior contradictory or inconsistent statements by the witness being questioned.

12 O.S. §§ 12-2608, 12-2609, 12-2613.

Reputation or opinion testimony as to truthfulness may only be sought if the witness’s truthfulness has been called into question. There are restrictions on using evidence of specific acts of truthfulness and untruthfulness in court – lawyers cannot use documents or other non-testimony evidence to prove specific acts. Further, lawyers cannot use evidence of a witness’s religious beliefs or opinions to impeach. 12 O.S. §§ 12-2608, 12-2609, 12-2610.

Any party to the case may attack a witness’s credibility, including the party who originally called the witness to the stand. 12 O.S. § 12-2607. In a typical criminal case, the defense will seek to impeach the prosecution’s witnesses and vice versa.

Have you been charged with a DUI in Oklahoma and need representation at pre-trial and trial proceedings? Clint Patterson, Esq., of Patterson Law Firm, a former Tulsa prosecutor, uses his trial experience and expert-level knowledge of DUI science to defend drivers. He has the experience and the insight to evaluate the strengths and weaknesses of your case. To schedule a case evaluation, visit Patterson Law Firm online or call Clint’s office at (918) 550-9175.