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Difference Between Lay Opinion Testimony and Expert Opinion Testimony


Although I have numerous blog articles regarding the appellate standard of review when it comes to the admissibility of evidence, it is important to remember that “[a] trial court’s ruling on the admissibility of evidence is reviewed for an abuse of discretion; however, the trial court’s interpretation of the evidence code is reviewed de novo.” L.L. v. The State of Florida, 41 Fla.L.Weekly D854a (Fla. 3d DCA 2016).

In L.L., a criminal case, a police officer testified that he smelled the strong odor of marijuana from the defendant and that a plastic bag in defendant’s possession contained marijuana. The defendant objected that the officer’s opinions about the smell being marijuana and the substance in the bag being marijuana was an improper lay opinion and constituted expert opinion testimony (governed by the Daubert standard). The trial court allowed this testimony and the issue on appeal was whether such testimony was expert opinion testimony or proper lay opinion (fact witness) testimony.

The appellate court held that the officer’s testimony or opinions about the smell and substance being marijuana was proper lay witness opinion testimony governed under Florida Evidence Code 90.701:

If a witness is not testifying as an expert, the [lay] witness’s testimony about what he or she perceived may be in the form of inference and opinion when:

(1) The witness cannot readily, and with equal accuracy and adequacy, communicate what he or she has perceived to the trier of fact without testifying in terms of inferences or opinions and the witness’s use of inferences or opinions will not mislead the trier of fact to the prejudice of the objecting party; and

(2) The opinions and inferences do not require a special knowledge, skill, experience, or training.

The appellate court’s holding included a very good discussion explaining in detail why the officer’s opinion was proper lay opinion testimony as opposed to expert opinion testimony governed by the Daubert standard:

In addition to the requirement that lay opinion testimony be based on the personal knowledge and perception of the witness, the Advisory Committee Notes explain that courts should consider the witness’s method of reasoning: “the distinction between lay and expert witness testimony is that lay testimony ‘results from a process of reasoning familiar in everyday life,’ while expert testimony ‘results from a process of reasoning which can be mastered only by specialists in the field.‘ ” …As one scholar has explained:

[T]he distinction lies in whether the witness’s reasoning process entails a reliable methodology beyond everyday reasoning. A lay witness, however experienced, offers no methodology beyond ordinary reasoning. An expert is equipped to draw more sophisticated, yet still reliable, inferences. The crux of expert testimony is that it presents inferences that are supported through the application of a reliable methodology. Thus, the witness who relies on experience to support an expert opinion cannot simply claim insights arrived at by applying everyday reasoning to that experience base, but must explain the methodology employed to reach that opinion. An experienced witness who does not bring such methodology to bear should be subject to the restrictions of the lay opinion rule.


One important reason the Daubert standard [governing the admissibility of expert witness opinions] imposes a more demanding reliability inquiry upon expert opinion testimony is that the opinion results from a methodology or reasoning process that might be foreign to the trier of fact….But in cases such as the one now before us, even if the trier of fact does not have the personal experience necessary to identify the substance in question, the reasoning process is not “foreign in kind.” Many people who have seen and smelled marijuana would be able to recognize it in the same way they recognize anything else they have seen or smelled before.


Here, Officer Munecas’s reasoning process is nothing that requires a specialist in the field of drug identification; it is reasoning familiar in everyday life.


Finally, we hasten to add that although the more demanding Daubert admissibility standard does not apply to lay opinion testimony, there is nevertheless a reliability inquiry. Not only must lay opinion testimony be based on the witness’s personal knowledge, section 90.604, Florida Statutes, and perceptions, section 90.701, Florida Statutes, but the witness must have sufficient personal knowledge to support the opinion.

L.L., supra (internal citations omitted).

Please contact David Adelstein at or (954) 361-4720 if you have questions or would like more information regarding this article. You can follow David Adelstein on Twitter @DavidAdelstein1.

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