What Evidence Can Your Lawyer Use to Impeach the Credibility of a Witness?

The credibility of a witness is a critical issue in any defense especially those involving allegations pertaining to illegal guns, drugs, and even DUI. In these criminal cases judges and juries will evaluate the truthfulness of police officers and civilian witnesses and their testimony pertain to the elements of each of these offenses.  This is especially important in cases where the defendant can’t testify because of his prior criminal history (aka prior conviction for dishonesty) or the defendant’s testimony wouldn’t otherwise benefit the defense’s strategy.

Credibility is important because witnesses may not make inconsistent statements at trial which is another way of bringing out an issue with the prosecution’s case. Unlike witness credibility, inconsistent statements at a preliminary hearing and a trial or motion imply that the witness is either embellishing what actually happened or doesn’t recall it clearly.

At a trial, the prosecution isn’t obligated to prove its case to a scientific certainty but only beyond a reasonable doubt. This is still a high evidentiary standard and so your criminal defense lawyer should use every opportunity to create reasonable doubt. The Pennsylvania Rule of Evidence 607(b) permits an attorney to impeach a witness with any evidence “relevant to that issue”. Impeachment, therefore, may expose a witness’s partiality, motive, prior convictions, character for untruthfulness as well as his lack of perception, recollection, or prior inconsistent statements. There are actually eight (8) categories which are open for impeachment:

  1. Competency – a witness’s ability to communicate, understand the consequences of lying, recall and proceed;
  2. Partiality – a person’s bias, prejudice, or other motivations which could corrupt or coerce their testimony;
  3. Motive – an issue that could possible color a witness’s testimony;
  4. Prior inconsistent statements – inconsistencies imply a possible credibility issue;
  5. Prior criminal convictions – a witness’s conviction for crimes for dishonesty and false statements can help prove untruthfulness;
  6. Untruthful character – a witness’s reputation for untruthfulness through a reputation witness;
  7. Untruthful acts – when a witness offers reputation testimony as to a person’s character that same witness may be asked about acts of untruthfulness; and
  8. Contradictions – a witness’s testimony may be contradicted by physical evidence, other accounts, or by witness’s inconsistent conduct.

Pennsylvania allows a fairly broad range of impeachment material but the attorney using it must have a good faith belief that the matters introduced are relevant and admissible. The cross examining attorney, therefore, can’t use something if it’s obviously not true. The attorney is also prohibited from asking questions in a fishing expedition type fashion (i.e. is it true that you …) The issue of witness credibility, again, is critical to your defense and this where a strong private investigator can dramatically change the outcome of a case from a defense standpoint.

For more information on this topic I encourage you to read my newsletters and check out the free resources in the download section.