Opinion testimony in Texas falls into two categories. Typically, opinions are given during expert testimony. However, non experts are permitted to give opinion testimony as well. However, non-expert opinion testimony has some requirements and limitations that expert testimony does not have.
The most significant requirement for non-expert testimony is that the witness testifying can only give their opinion if they have some sort of personal knowledge about the facts underlying the opinion testimony. People are not permitted to testify what their opinions are if they do not have actual independent information that forms the basis of their testimony.
RULE 701 OPINION TESTIMONY BY LAY WITNESSES
If the witness is not testifying as an expert, the witness’ testimony in the form of opinions or inferences is limited to those opinions or inferences which are (a) rationally based on the perception of the witness and (b) helpful to a clear understanding of the witness’ testimony or the determination of a fact in issue.