Lay Opinion and Personal Knowledge

Lay Opinion and Personal Knowledge

Personal knowledge limits what a witness may say about a matter, but ordinary witnesses rarely speak in bare sensory reports. A driver who saw a truck approach says it was speeding, a neighbor says a child looked frightened, and a listener says a voice sounded drunk. Each of those statements is an inference drawn from perception, which raises the question whether the requirement that a witness speak from her own senses forbids such conclusions. It does not, and the reason tells you how Rule 701 and Rule 602 fit together.

Fact and opinion are not two sharply separate kinds of testimony. Even a statement that a defendant was holding a gun uses the witness's knowledge of what guns look like to draw an inference from what she saw.¹ Because the line is so hard to draw, the modern Rules treat facts and opinions as points on a continuum, with facts more concrete and opinions more general, and they do not bar lay opinion outright.² The older worry that an opinion without a perceptual basis is mere guesswork is answered instead by Rule 602, which asks whether the witness perceived the matter on which the opinion rests.³ Rule 701 then supplies the conditions under which the inference itself may be voiced.

The Rule 701 Conditions

A witness who is not testifying as an expert may give an opinion only if it is rationally based on her perception, helpful to understanding her testimony or to determining a fact in issue, and not based on scientific, technical, or other specialized knowledge within the scope of Rule 702.⁴ Before she gives the opinion, the proponent must also lay a foundation showing she has personal knowledge of the facts underneath it.⁵ The reason for tying the opinion to perception is that it keeps the conclusion checkable. Opposing counsel can ask what the witness saw, how long she saw it, and from where, and the jury can judge whether the conclusion follows. The helpfulness condition guards against a different problem, the witness who simply takes sides when the jurors have the information they need to draw the inference themselves.⁶

In practice the proponent must show two things: the witness is relying on a generalization she developed through personal experience, and she has personal knowledge of the case-specific fact to which the generalization is applied. If either is missing, the conclusion cannot come in as lay opinion.⁷ A witness may not say that something smelled like dynamite unless the foundation shows that she knows from prior experience what dynamite smells like.⁸ She may have smelled the substance perfectly well, but without the experiential generalization her sensation does not support the label. Three opinions from a single invented witness show how the two elements work together.

Imagine a pedestrian named Wyn who was jogging when a vehicle passed her and who later testifies in a collision suit. She says a screeching sound she heard was a vehicle braking, and she has experience with that sound, so the opinion is rationally based on what she heard and gives the jury a fuller picture than a description of a loud, high-pitched noise would.⁹ She then offers that the sound came from the defendant's SUV, but she did not see the vehicle while it made the noise, so she lacks the sensory perception needed to know the source of the sound. That problem can be framed under Rule 701 or Rule 602, and either way an objection is properly sustained.¹⁰ The third opinion is a specific speed in miles per hour. Wyn was running in the opposite direction and had no reference point of her own speed, so a precise figure was not rationally based on her perception, yet the court allowed her to say the SUV was going faster than 25 and faster than 40 but not, she thought, faster than 60.¹¹ The coarser estimate fits what she could actually perceive, which is the whole point of the link between perception and opinion.

Experience as a general matter does not substitute for perception of the particular event. In Gorby v. Schneider Tank Lines, a motorist in another car testified that a tanker driver did everything he could to avoid a collision, and the court affirmed the exclusion of that testimony. The motorist was not in the cab, could not know what measures the driver took or when the driver first saw the other truck, and had never been shown to know the tanker's equipment or stopping distances.¹² His twenty-nine years of driving did not give him the knowledge of the case-specific facts that the opinion required.¹³ Two points soften the requirement. A witness who is unsure may still testify if she qualifies the opinion with phrases such as 'I believe' or 'I can't be positive, but,' since absolute certainty is not required.¹⁴ And a witness who bases an opinion on what someone else told her must separate two cases. If she relies only on the fact that the statement was made, as when she heard a man say he was the Queen of England and concludes he is insane, the opinion rests on her own hearing. If she relies on the truth of what the speaker asserted, as when she concludes that he is the rightful heir to the throne, the opinion rests on the speaker's perception and not on hers.¹⁵

Officers and Specialized Knowledge

The third condition of Rule 701 matters most for witnesses whose experience is professional. When an officer in United States v. Ayala described how drug points operate, he rested on more than 100 occasions of investigating, patrolling, or making arrests at them. His testimony recounted what occurred there, so it rested on personal knowledge, and the court treated it as lay testimony requiring no expert notice.¹⁶ His account of how heroin was packaged in aluminum decks was likewise a report of what he had seen, leaving the jury to draw its own conclusions, and the defense could test his perceptions on cross-examination.¹⁷ United States v. Freeman marks the contrast. A case agent who had listened to some 23,000 recorded calls told the jury what the speakers meant by ordinary words used in ordinary ways. The court held that an agent testifying as a lay witness may not tell the jury what inferences to draw from conversations in plain language, because at that point the testimony is no longer evidence and becomes argument.¹⁸ What separates the two decisions is the source of the knowledge. The officer in Ayala reported what he personally observed, while the agent in Freeman supplied conclusions the jurors could reach themselves, with the added weight of his position.

Because the personal knowledge foundation comes first, the analysis of any lay opinion can be run in an orderly way.

A failure at step one is a personal knowledge problem, and a failure at steps two through five is a Rule 701 problem, though the two rules overlap as the source-of-sound example shows.