In a Missouri car accident injury case I am currently handling. my client suffered a severe head injury. The defense appointed an expert and that expert attempted to opine about his belief of one witness' testimony regarding the facts of the case; specifically he opined he did not believe a witnesses account of how the head injury has affected the victim's life and believed they were not telling the truth. As an experienced Missouri personal injury lawyer, I am always looking down the road at what may come up at trial and how to prevent any potentially bad evidence from getting in front of a jury.
In Misssouri personal injury cases, lawyers cannot put on experts to testify, that in their opinion, another witness is telling the truth or not. Missouri case law is clear that, "expert testimony is inadmissible if it relates to the credibility of witnesses because it invades the province of the jury." State v. Link, 25 S.W.3d 136, 143 (Mo. banc 2000). It is the jury's charge and responsibility to decide issues of fact, which includes credibility of witnesses.
Additionally, non expert witnesses, lay witnesses, in a personal injury case, generally cannot testify about the truth or veracity of another witness. Missouri courts have long held that a witness should not give his or her opinion upon the truth of a statement by another witness. Stone v. City of Columbia, 885 S.W.2d 744, 746 (Mo.App.1994)
A good Missouri personal injury attorney knows that although it is not proper to present testimony that in one witness's opinion another witness is or is not telling the truth, a witness may testify to facts that may have the effect of discrediting the witness before the jury without invading the province of the jury. Stone, 885 S.W.2d at 747.
Additionally, witnesses may testify that a party has a reputation in the community, or within a group, of being untruthful. But may not testify that the personal is untruthful if that is simply based on a prior bad act or just that witness' personal opinion.
A person is qualified to testify as to another witness's reputation for truthfulness and veracity if it is shown that the person is familiar with "the general reputation of the witness in the neighborhood or among the people with whom the witness associates...." State v. Woods, 428 S.W.2d 521, 523 (Mo. 1968). Conversely, it is irrelevant what the person personally knows of the general conduct of the witness to be impeached because personal opinion as to a witness's truthfulness and veracity "is immaterial and not admissible." State v. Schell, 843 S.W.2d 382, 384 (Mo.App.E.D. 1992) (quoting State v. Huffman, 607 S.W.2d 702, 704 (Mo.App.E.D. 1980)).