A lay witness is someone who provides testimony in court based on their direct perceptions or personal experiences concerning the case. Federal Rule of Evidence 701 states that if a witness is not providing expert testimony, lay testimony in the form of an opinion is limited to one that is:
- Rationally based on the witness’s perception;
- Helpful to clearly understanding the witness’s testimony or to determining a fact in issue; and
- Not based on scientific, technical, or other specialized knowledge within the scope of Federal Rule of Evidence Rule 702 as an expert witness.
Lay witnesses are typically individuals who were present at the scene of the incident, were involved in the circumstances leading to the case, or possess knowledge that could shed light on the case's facts. Such witnesses generally can offer opinions relating to degrees of distance, sound, light, weight, and a person’s manner of conduct and appearance, and/or identity. In addition, lay witnesses’ perceptions must be rationally based.
In the advisory notes to Rule 701, it is stated: “Witnesses often find difficulty in expressing themselves in language which is not that of an opinion or conclusion. While the courts have made concessions in certain recurring situations, necessity as a standard for permitting opinions and conclusions has proved too elusive and too unadaptable to particular situations for purposes of satisfactory judicial administration.”
Trial judges possess great discretion to determine when lay testimony is admissible evidence. 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. What constitutes personal knowledge can be quite broad, as lay witnesses can and do testify to an array of various matters. Generally, courts have held that observation of an event falls within the definition of personal knowledge.
The opinions that lay witnesses have been permitted to testify about vary widely throughout jurisdictions. For example, judges in federal courts have differed as to whether lay opinion testimony is admissible under Rule 701 for law enforcement officers.
Federal courts in the Tenth and Eleventh Circuits’ have allowed lay opinion testimony from law enforcement officers who have general knowledge of the investigation in question, without requiring personal perception of the events upon which the witness is testifying. See United States v. Jayyousi, 657 F.3d 1085, 1102 (11th Cir. 2011) (allowing a police officer to give an after-the-fact opinion as to the meaning of coded words in a conversation).
In contrast, federal judges in the Second, Fourth, and Eighth circuit courts have limited what is admissible as lay opinion for law enforcement by more narrowly interpreting the definitions of helpfulness and first-hand knowledge. For example, in United States v. Garcia, 413 F.3d 201(2d Cir. 2005), the federal court emphasized the distinction between a law enforcement officer’s lay opinion testimony that is based on their perceptions (such as personally hearing a phone call) and lay opinion testimony that is based on the entirety of an investigation.
[Last updated in August of 2023 by Jim Robinson, Esq., JurisPro Expert Witness Directory]