A lot of cases involving children and allegations of abuse have expert witnesses at trial. For example, there are experts in evaluating child abuse allegations and they may work for CPS or a Child Advocacy Center. These witnesses want to testify that a child is telling the truth in an allegation, and many trial courts will allow such testimony. However, in Texas the law is clear that experts may not testify a witness is telling the truth.
What’s the law say?
Expert testimony that a particular witness is truthful is inadmissible under TEX. R. EVID. 702. Therefore, an expert witness may not offer a direct opinion on the truthfulness of a child complainant’s allegations. Schutz v. State, 957 S.W.2d 52, 59 (Tex. Crim. App. 1997).
However, even if the State cheats at trial and has their expert testiy that a child or other witness is telling the truth our appellate courts will usually say that’s ok.
The erroneous admission of evidence is nonconstitutional error. Casey v. State, 215 S.W.3d 870, 885 (Tex. Crim. App. 2007). Nonconstitutional error requires reversal only if it affects the substantial rights of the accused. See TEX. R. APP. P. 44.2(b); Barshaw v. State,342 S.W.3d 91, 93 (Tex. Crim. App. 2011). Appellate courts will not overturn a criminal conviction for nonconstitutional error if, after examining the record as a whole, they have fair assurance the error did not influence the jury or influenced the jury only slightly. Barshaw, 342 S.W.3d at 93.
Guess what? Texas appellate courts will almost always find that non-consitutional error didn’t influence the jury, so even though the State broke the rules at trial, the conviction stands.