improper expert opinion from a lay witness

As an extension of this rule, lay witnesses generally cannot answer hypothetical questions, as all of their opinions must be based on facts they personally observed. Therefore, lay opinions must be wholly independent of expert testimony. Lastly, lay opinions cannot be based on scientific, technical, or other specialized knowledge within the scope of Rule 702. Unlike an expert offering his own scientific, technical, or other specialized knowledge to assist the jury with complex issues, lay opinion testimony is usually considered helpful when the witness is in a better position than the jury to form an opinion and the facts alone would be inadequate to provide a complete understanding of the testimony.

Similar to Rule 702’s requirements for expert testimony, lay witness testimony must be helpful to the fact-finder. Witnesses are only required to use their everyday logic to reach their conclusion. However, the standard of rational perception is not rigorous. In addition, lay witnesses’ perceptions must be rationally based. Lay witnesses can offer opinions relating to degrees of light, sound, weight, and distance, as well as a person’s appearance, identity, or manner of conduct. The opinions that lay witnesses have been permitted to testify about vary widely throughout jurisdictions. Whether as a first-hand witness to a car accident or crime, lay opinions may be rendered about what the witness observed.Ĭourts have also held that lay witnesses may testify to their perception of the incident if obtained through earlier personal observations. Generally, courts have held that observation of an event or situation clearly falls within the definition of personal knowledge. Of course, what constitutes personal knowledge can be quite broad, as lay witnesses can and do testify to an array of various matters. Lay witnesses, however, are constrained by relying on information they have gained through personal knowledge and rationally based perception. Rather, experts can consider facts that would otherwise be inadmissible, so long as experts in their particular field would reasonably rely on such information. In comparison, Rule 703 allows experts to rely upon facts and data beyond what they have personally observed. Rule 602 specifically exempts expert testimony from this requirement. Rule 602 of the Federal Rules of Evidence requires that a witness may only testify if evidence is sufficient to support a finding that the witness has personal knowledge of the matter. While experts may use their knowledge or skill to draw conclusions, lay witnesses can only base their opinions on information they personally observed. The major difference between these two types of witnesses is personal knowledge. (a) rationally based on the witness’s perception (b) helpful to clearly understanding the witness’s testimony or to determining a fact in issue and (c) not based on scientific, technical, or other specialized knowledge within the scope of Rule 702 Personal Knowledge is Required In contrast, Rule 701 of the Federal Rules of Evidence states that if a witness is not testifying as an expert, testimony in the form of an opinion is limited to one that is: (a) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue (b) the testimony is based on sufficient facts or data (c) the testimony is the product of reliable principles and methods and (d) the expert has reliably applied the principles and methods to the facts of the case

Under Rule 702, a witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if: Lay opinion testimony is largely defined by what it is not-expert testimony. How Do Lay Opinions Differ from Expert Opinions? In order to ensure that your expert testimony is utilized to its full potential, it is important to note the differences between the two types of witnesses so that both can offer admissible opinions.

Now, both lay and expert opinions are admissible at trial, to varying degrees. Once Rule 701 of the Federal Rules of Evidence was enacted, the restrictions on lay opinions began to loosen. However, as the Supreme Court has noted, there is an “inevitably arbitrary line between the various shades of fact/opinion”. The justification was that unless the information was too complex for a jury to understand without the help of an expert, a jury should be able to interpret evidence and draw its own conclusions.

Improper expert opinion from a lay witness