Perhaps the most effective and most frequently used form of impairing credibility is proof of a statement or conduct by the witness that is inconsistent with the trial testimony. (Ev. C. § 780(h) (pdf)) The inconsistency need not be a complete contradiction. The test is whether the prior statement is inconsistent in effect with the trial testimony. People v. Spencer (1969) 71 Cal.2d 933 (pdf), 941.
A primary consideration of whether you should impeach with a prior inconsistent statement is the degree of the inconsistency. Was the prior statement of any material significance? If not, you may lose credibility by being petty. Of course, if your case needs all the help it can get and there are several “small” inconsistencies that you can spin into a pattern, you may have no other choice but to go there.
A. PRIOR INCONSISTENT STATEMENTS
The first step in impeachment by prior inconsistent statements is to ensure that the witness has committed to the new statement. Leave no escape. This can be achieved by doubling back and having the witness reiterate the new statement by your use of specific leading questions – do not paraphrase the witness’s new testimony. This precludes the witness from claiming that they misunderstood the question that lead to the new statement or that they simply misspoke. Next, lay foundation for the prior inconsistent statement being the most believable: have the witness confirm that they gave a prior statement, they may have written/signed a statement, they were trying to be accurate, their recollection of events was better back then, they were trying to be truthful, it was a sworn statement, etc. Then you must confront the witness with the prior statement – have them confirm that they gave the prior statement and their signature appears on it. Now is the time to bring it all together. Show the reasons that the witness has changed the testimony (e.g., they were contacted by an attorney, they spoke to a party, they became a party, etc.) Do not ask the witness for an explanation for the change. You have reached your goal.
B. INCONSISTENT CONDUCT
A witness’ conduct may also be shown to impeach. If a witness states that they have never acted in a certain manner and there is evidence that they have, their credibility will be impeached. An example in an auto case is a plaintiff testifying that they habitually wear a seat belt and did so in the subject collision, but subsequent subrosa surveillance shows that the witness was driving without being belted.
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