Lay opinion and expert qualification

The Classification Gate: Perception Ends Where Specialized Knowledge Begins

Federal Rules of Evidence 701 and 702 divide opinion testimony according to the source of the witness’s knowledge and the help that testimony can provide the factfinder.

For a witness not testifying as an expert, Rule 701 permits an opinion only if all three requirements are met:

The opinion is rationally based on the witness’s perception.
The opinion is helpful to clearly understanding the witness’s testimony or to determining a fact in issue.
The opinion is not based on scientific, technical, or other specialized knowledge within the scope of Rule 702.

The first requirement is narrower than “the witness knows something.” The witness must have perceived facts that support the inference. A witness who watched a vehicle approach may estimate its speed, describe whether a person appeared intoxicated, or characterize someone’s emotional condition. But the witness cannot convert an unsupported guess into a lay opinion merely by saying, “That is what I believe.”

The second requirement asks what the opinion contributes. The opinion must help the factfinder understand the witness’s observations or decide a disputed fact. An opinion that merely repeats an obvious fact, supplies speculation, or gives the witness’s preferred conclusion without a perceptual foundation is not helpful in the Rule 701 sense.

The third requirement separates lay opinion from expert testimony. A witness may have substantial experience, but if the opinion depends on scientific, technical, or other specialized knowledge, Rule 701 is not the route. The proponent must satisfy Rule 702 instead. The witness’s job title does not decide the classification; the basis of this particular opinion does.

A witness’s underlying observations and the witness’s opinion are also distinct. A witness may be allowed to testify, “I saw the truck move from the intersection to the parked car,” while being barred from adding a technical reconstruction of the truck’s speed. Failure to satisfy Rule 701 excludes the opinion under Rule 701; it does not automatically erase otherwise admissible observations.

For a proposed opinion, run the classification questions in this order:

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If the opinion uses specialized knowledge, move directly to Rule 702. If it does not, ask whether the opinion rests on the witness’s own perception. If both answers are no, neither Rule 701 nor the lay route permits the opinion. This is a closed-book topic: commit Rule 701’s three requirements and Rule 702’s five-part structure to memory.

Question	Lay witness under Rule 701	Expert witness under Rule 702
What is the knowledge source?	The witness’s own perception of particular facts	Scientific, technical, or other specialized knowledge
What must the testimony do?	Help explain the testimony or determine a fact	Help the trier of fact understand evidence or determine a fact
What qualification is required?	No expert qualification because the witness is not testifying as an expert	Knowledge, skill, experience, training, or education in the relevant area
What is the principal boundary?	The opinion cannot be based on specialized knowledge within Rule 702	The opinion must fit the witness’s actual expertise and satisfy the other Rule 702 requirements
What happens if the gate fails?	The opinion is not admitted as lay opinion under Rule 701	The proposed expert testimony is not admitted under Rule 702

The Expert’s Reach: Credentials Must Fit the Proposition

Rule 702 asks whether the witness is qualified by knowledge, skill, experience, training, or education. These are alternative sources of qualification. The witness need not possess all five, and no particular degree, license, or professional title is automatically required.

Qualification is proposition-specific. Do not ask merely, “Is this person an expert?” Ask, “Is this person qualified to give this particular testimony?” An engineer may be qualified to explain stress on a bridge but not to diagnose a medical condition. A physician may be qualified to explain a bodily injury but not to reconstruct a vehicle’s braking distance. A mechanic may be qualified through years of hands-on work even without an engineering degree, but that experience must concern the subject of the opinion.

The near miss is between a credential that sounds impressive and competence in the precise field at issue. A chemistry doctorate does not by itself qualify a witness to reconstruct a collision. Conversely, the absence of a formal degree does not disqualify an experienced tradesperson from explaining a technical installation practice. The question is whether the witness’s knowledge, skill, experience, training, or education supplies genuine competence for the proposed testimony.

Qualification is also distinct from reliability. A witness can be qualified yet offer testimony that fails Rule 702’s separate requirements. Conversely, a sound method does not cure a witness’s lack of competence in the subject. The sibling chapter on expert reliability, bases, and ultimate issues handles those separate limits; here, keep the qualification question separate from the method question.

Qualification disputes often turn on the level of generality used to describe the field:

“Automotive expert” is too broad to decide anything.
“Collision reconstruction specialist with twelve years analyzing braking distances” is tied to a specific proposition.
“Physician” does not answer whether the witness can testify about every medical specialty.
“Experienced technician” may be enough if the experience directly concerns the machine, process, or problem at issue.

Once the witness is properly qualified, the testimony still must satisfy Rule 702 as a whole. Rule 702 permits testimony in the form of an opinion or otherwise when the witness’s specialized knowledge will help the trier of fact understand the evidence or determine a fact in issue. The rule also requires that the testimony be based on sufficient facts or data, be the product of reliable principles and methods, and reflect reliable application of those principles and methods to the facts of the case.

Those requirements create two important near-miss distinctions.

Qualification versus helpful subject matter. A witness may be highly qualified, but the proposed testimony may not require expertise or may not assist the factfinder. The witness’s impressive background does not make every statement admissible expert testimony. For example, an engineer may be qualified to explain how a braking system functions, but a bare statement that “the driver acted badly” does not become helpful technical testimony merely because an engineer says it.

Specialized subject matter versus ordinary perception. A lay witness may estimate speed from watching a vehicle, because the inference can arise from perception. The same witness may need Rule 702 if the opinion depends on calculating speed from skid marks, braking forces, angles, or other technical measurements. The decisive fact is not that the witness has an opinion about speed; it is whether the opinion comes from ordinary perception or specialized analysis.

Proper expert subject matter includes scientific, technical, and other specialized knowledge. “Other specialized” matters because Rule 702 is not limited to laboratory science. An expert may explain an industrial process, interpret technical measurements, reconstruct a collision, analyze a specialized accounting system, or describe how a particular machine operates. In each example, the testimony is proper only if the specialized knowledge will help the trier of fact and the remaining Rule 702 requirements are satisfied.

A useful way to test subject matter is to remove the witness’s title. Ask: Would the testimony give the factfinder specialized assistance in understanding evidence or deciding a fact, or is it simply an ordinary observation, speculation, or a conclusion dressed in professional language? If the former, Rule 702 may apply. If the latter, the witness’s credentials do not supply the missing foundation.

Recurring errors:

Treating a police officer’s estimate based on watching a car as expert testimony solely because the witness is a police officer.
Treating a chemistry doctorate as qualification to reconstruct braking distance when the witness has no collision-reconstruction experience.
Treating the absence of a degree as disqualifying a technician whose years of relevant practical experience directly match the opinion.
Treating qualification in one field as qualification to address every technical issue involving the same general subject.
Treating specialized subject matter as sufficient without asking whether it will help the factfinder understand evidence or decide a fact.

A Collision Record: Two Defensible Routes in Six Choices

A delivery van struck a pedestrian at an intersection. Marta watched the van for several seconds before impact and testified that it was traveling “about 45 miles per hour”; she has no scientific or technical training in speed measurement. The estimate would help the jury determine the van’s speed.

Dr. Chen has an engineering degree, twelve years of experience reconstructing vehicle collisions, and specialized training in braking analysis. He has sufficient measurements from the scene, uses a reliable method, and reliably applies that method to the measurements. His proposed opinion concerns the van’s braking distance and would help the jury understand the collision.

The proponent offers both opinions.

Practice

Select two answers that are supported by the Federal Rules of Evidence.

	(A) Marta may give the estimate of approximately 45 miles per hour.	(B) Marta’s estimate is inadmissible because a lay witness may never estimate a vehicle’s speed.	(C) Dr. Chen may give the braking-distance opinion under Rule 702.	(D) Dr. Chen is unqualified because only a formal scientific doctorate can qualify an expert.	(E) Dr. Chen is automatically qualified to give every opinion concerning vehicles because he is qualified in collision reconstruction.	(F) Dr. Chen cannot testify because Rule 702 covers scientific knowledge but not technical or other specialized knowledge.
Your answers

Three Short Tests: One Rule and One Fact at a Time

Practice

A bystander watched a collision and says, “The sedan was moving too fast,” based on observing its movement for several seconds. The bystander has no technical training, and the opinion would help the jury evaluate the sedan’s speed. May the bystander give the opinion?

A manufacturing supervisor has no college degree but has spent twenty years installing and repairing the type of industrial valve involved in the dispute. The supervisor proposes to explain how that valve normally fails, and the experience directly concerns the valve’s operation. Is the supervisor qualified to offer expert testimony on that subject?

A digital-forensics specialist has fifteen years of experience interpreting computer metadata. The specialist proposes to explain how a file’s creation and modification records work, and that explanation would help the jury understand the records. Which statement is most accurate?

High-Yield Points - ⚡ Biggest Takeaways

Apply Rule 701 only when the opinion comes from perception rather than specialized knowledge. Match every Rule 702 qualification to the precise proposition the expert will offer. Proper expert subject matter is scientific, technical, or otherwise specialized knowledge that helps the factfinder.

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Practice Questions: Lay opinion and expert qualification

1. A pedestrian sued a delivery company after one of its vans struck her in a crosswalk. The company disputes whether the pedestrian entered the crosswalk against the signal. The pedestrian offers testimony from a traffic engineer that, during an inspection conducted two weeks after the collision at the same time of day, a tree partially blocked drivers’ view of the pedestrian signal. Weather records show that there had been no storm or pruning between the collision and inspection, and photographs taken on both dates show the tree in substantially the same condition. The company objects that the inspection occurred after the collision and that the testimony may cause jurors to decide the case based on a different event. The pedestrian offers the testimony to show what the driver could see when approaching the crosswalk. Is the court likely to admit the testimony?

A. Yes, because the inspection conditions were shown to be substantially similar, and the testimony is probative of the driver’s ability to see the signal.
B. Yes, because relevant evidence cannot be excluded merely because it may influence the jury’s assessment of a disputed fact.
C. No, because observations made after an accident are inadmissible unless the opposing party attended the inspection.
D. No, because the later inspection creates unfair prejudice that substantially outweighs its probative value.

Show answer

Answer: A. Yes, because the inspection conditions were shown to be substantially similar, and the testimony is probative of the driver’s ability to see the signal.

Yes, because the inspection conditions were shown to be substantially similar, and the testimony is probative of the driver’s ability to see the signal. - The engineer’s observation is probative of visibility because the photographs show the tree in substantially the same condition on the collision and inspection dates. - The absence of storms or pruning supports admitting the later observation; the two-week gap goes to its weight. Yes, because relevant evidence cannot be excluded merely because it may influence the jury’s assessment of a disputed fact. - The testimony is relevant because it helps establish what the driver could see when approaching the crosswalk. - But relevant evidence can be excluded under Rule 403 if a qualifying danger substantially outweighs its probative value. No, because observations made after an accident are inadmissible unless the opposing party attended the inspection. - The company’s attendance is not a prerequisite to admitting the engineer’s observations. - The pertinent question is whether conditions at the later inspection were sufficiently similar to those at the collision. No, because the later inspection creates unfair prejudice that substantially outweighs its probative value. - Jurors drawing an inference about visibility from the engineer’s testimony is its proper evidentiary use, not unfair prejudice. - The substantially unchanged tree supports probative value, and the record identifies no Rule 403 danger that substantially outweighs it.

2. A delivery driver sued a warehouse owner after a loading-platform railing collapsed. Two days after the accident, the owner replaced the railing and added warning signs. At trial, the owner denies owning the platform and contends that a neighboring business controlled it. The driver offers the owner's work order directing employees to replace "our damaged platform railing." The driver states that the work order is offered only to prove ownership and control, not negligence or culpable conduct. The owner objects that evidence of repairs made after an accident is inadmissible. Which of the following best states how the court should rule?

A. Exclude the work order because evidence of a subsequent repair is inadmissible for every purpose.
B. Admit the work order because ownership or control is disputed and the evidence is offered for that permitted purpose.
C. Exclude the work order unless the driver first proves that the owner acted negligently before making the repair.
D. Admit the work order as proof that the original railing was defective because the repair acknowledges the defect.

Show answer

Answer: B. Admit the work order because ownership or control is disputed and the evidence is offered for that permitted purpose.

Admit the work order because ownership or control is disputed and the evidence is offered for that permitted purpose. - Rule 407 permits evidence of a subsequent remedial measure to prove ownership or control when that issue is disputed. - The owner denies controlling the platform, and the work order’s reference to “our damaged platform railing” bears on that dispute; the court may limit the jury to that use. Exclude the work order because evidence of a subsequent repair is inadmissible for every purpose. - Rule 407 does not bar subsequent-repair evidence for every purpose. - Because the owner disputes ownership and control, the driver may offer the work order on those issues rather than to prove negligence. Exclude the work order unless the driver first proves that the owner acted negligently before making the repair. - Rule 407 imposes no requirement that the driver first prove negligence to use the work order for disputed control. - The driver’s stated purpose is to show who controlled the platform, not whether the owner acted negligently. Admit the work order as proof that the original railing was defective because the repair acknowledges the defect. - Rule 407 does not permit the driver to use the replacement as proof that the original railing was defective. - The work order may be considered for disputed ownership or control, but the repair cannot be treated as an admission of liability.

3. A factory worker brought a negligence action against a press manufacturer after the press crushed his hand. The worker claims that the press should have included a fixed barrier preventing an operator's hand from reaching the compression area. After the accident, the manufacturer added such a barrier to newly produced presses. Before trial, the manufacturer's expert testified that adding a fixed barrier to this model was not technically feasible because it would prevent operators from positioning materials. The worker seeks to introduce evidence of the post-accident design change solely to rebut that testimony. The manufacturer objects that the change is a subsequent remedial measure and that the jury might misuse it as proof of negligence. Is the court likely to admit the evidence?

A. Yes, because the manufacturer disputed feasibility and the court may give a limiting instruction restricting the jury's use of the evidence.
B. Yes, because subsequent remedial measures are excluded only when undertaken by someone other than the defendant.
C. No, because a subsequent design change is inadmissible for every purpose when it could suggest earlier negligence.
D. No, because feasibility evidence is admissible only if the manufacturer expressly stipulated that the original design was unsafe.

Show answer

Answer: A. Yes, because the manufacturer disputed feasibility and the court may give a limiting instruction restricting the jury's use of the evidence.

Yes, because the manufacturer disputed feasibility and the court may give a limiting instruction restricting the jury's use of the evidence. - Under Federal Rule of Evidence 407, a subsequent design change may be admitted to prove feasibility when feasibility is disputed; the manufacturer’s expert testified that a fixed barrier would prevent operators from positioning materials. - The court may give a limiting instruction allowing the jury to consider the new barrier on feasibility, but not as proof that the manufacturer was negligent. Yes, because subsequent remedial measures are excluded only when undertaken by someone other than the defendant. - Rule 407 generally restricts the use of a defendant’s subsequent remedial measures to prove negligence; it does not apply only to measures taken by someone else. - The manufacturer’s change may be admitted here because its expert disputed feasibility, not because the manufacturer was exempt from the rule. No, because a subsequent design change is inadmissible for every purpose when it could suggest earlier negligence. - Rule 407 does not bar a subsequent remedial measure for every purpose merely because a jury might also view it as evidence of negligence. - The worker offers the added barrier solely to rebut the expert’s claim that such a barrier was not technically feasible, a permitted purpose when feasibility is disputed. No, because feasibility evidence is admissible only if the manufacturer expressly stipulated that the original design was unsafe. - A stipulation that the original design was unsafe is not required to admit a subsequent measure to prove disputed feasibility. - The expert’s testimony that a fixed barrier would interfere with positioning materials itself placed feasibility in dispute.

4. A factory worker brought a negligence action against an equipment leasing company after the worker's hand passed through an opening beside a blade on a machine the leasing company had supplied and serviced. Two months after the accident, the leasing company added a wider guard to the machine. The worker proposes to introduce evidence of that change. The leasing company disputes that it had control over maintaining the machine at the time of the accident, contending that the factory owner alone was responsible for its upkeep. The worker argues that the evidence should be admitted specifically to establish control. Which of the following best states how the court should rule?

A. Admit the evidence to show that the leasing company had control over the machine because the leasing company disputes control.
B. Admit the evidence to prove that the leasing company was negligent because the replacement reduced the risk.
C. Exclude the evidence because post-accident remedial measures are inadmissible for every purpose.
D. Exclude the evidence because control is irrelevant whenever a plaintiff alleges negligent maintenance.

Show answer

Answer: A. Admit the evidence to show that the leasing company had control over the machine because the leasing company disputes control.

Admit the evidence to show that the leasing company had control over the machine because the leasing company disputes control. - Adding a wider guard two months later was a subsequent remedial measure, but Rule 407 permits such evidence to prove control when control is disputed. - Because the leasing company denies responsibility for maintaining the machine at the time of the accident, its later alteration is relevant to control, not proof of negligence. Admit the evidence to prove that the leasing company was negligent because the replacement reduced the risk. - A wider guard may have reduced the risk of a hand reaching the blade, but Rule 407 bars using the later change to prove negligence. - The worker’s stated purpose—establishing disputed control—is what makes the evidence admissible. Exclude the evidence because post-accident remedial measures are inadmissible for every purpose. - Rule 407 does not impose an absolute bar: a subsequent remedial measure may be admitted to prove control when that issue is disputed. - The leasing company’s claim that the factory owner alone handled upkeep makes that exception applicable here. Exclude the evidence because control is irrelevant whenever a plaintiff alleges negligent maintenance. - Control matters to a negligent-maintenance claim because it bears on who was responsible for maintaining the machine. - The leasing company expressly disputes that responsibility, so its addition of the guard has a permissible evidentiary purpose.

5. A pedestrian sued a grocery store in federal court after tripping over an unguarded loading-ramp edge. The pedestrian alleges that the store negligently failed to install a protective railing. At trial, the store's facilities director testifies that the store did not own or control the loading ramp because that portion of the property had been leased to an independent contractor responsible for its maintenance. The pedestrian then offers evidence that, one week after the accident, the store's own maintenance crew installed a protective railing on the ramp. The pedestrian offers the evidence only to rebut the director's assertion that the store lacked control over the ramp. The store objects under the rule excluding subsequent remedial measures. Which of the following is the court's most appropriate ruling?

A. Exclude the evidence because subsequent remedial measures cannot be admitted for any purpose in a negligence action.
B. Exclude the evidence because control is relevant only if the store expressly concedes that it controlled the ramp.
C. Admit the evidence for the limited purpose of proving control because the store placed control in dispute.
D. Admit the evidence as substantive proof that the store was negligent because the later repair establishes the applicable standard of care.

Show answer

Answer: C. Admit the evidence for the limited purpose of proving control because the store placed control in dispute.

Admit the evidence for the limited purpose of proving control because the store placed control in dispute. - Federal Rule of Evidence 407 permits a subsequent remedial measure to prove control when control is disputed, and the facilities director denied that the store controlled the ramp. - The store’s own crew installed the railing, making that work relevant to control; if requested, the court should instruct the jury to consider it only for that purpose. Exclude the evidence because subsequent remedial measures cannot be admitted for any purpose in a negligence action. - Rule 407 bars using the later railing installation to prove negligence, but it does not bar every use of that evidence. - The pedestrian offers the crew’s work to rebut the director’s denial of control, a permitted use. Exclude the evidence because control is relevant only if the store expressly concedes that it controlled the ramp. - The director’s testimony that an independent contractor controlled the ramp disputes control rather than conceding it. - That dispute is why the store’s subsequent installation of a railing can be considered as evidence of control. Admit the evidence as substantive proof that the store was negligent because the later repair establishes the applicable standard of care. - Rule 407 prohibits using the later railing installation as proof that the store acted negligently before the accident. - The crew’s work may bear on who controlled the ramp, but it does not establish the applicable standard of care.

6. A factory worker brought a products-liability action against the manufacturer of a conveyor belt system after the worker's arm was caught in an unguarded pinch point. The worker alleges that the system was defectively designed because a readily available guard could have prevented the injury. At trial, the manufacturer's plant supervisor testified, "We never even considered adding a guard to that pinch point because we didn't think one was necessary." The worker then offered evidence that, one month after the accident, the manufacturer added a guard over the pinch point on the same model of conveyor system. The manufacturer objected. The worker stated that the evidence was offered only to impeach the supervisor's testimony that a guard had never been considered, not to prove negligence or a defective design. How should the court rule?

A. Admit the evidence because it may be used to impeach the supervisor's testimony that a guard was never considered.
B. Admit the evidence because post-accident design changes are substantive proof that the earlier design was defective.
C. Exclude the evidence because a later safety measure cannot be used for any purpose in a products-liability action.
D. Exclude the evidence because later design changes are privileged communications prepared in anticipation of litigation.

Show answer

Answer: A. Admit the evidence because it may be used to impeach the supervisor's testimony that a guard was never considered.

Admit the evidence because it may be used to impeach the supervisor's testimony that a guard was never considered. - The supervisor’s categorical statement that the manufacturer never considered a guard is open to impeachment with evidence that the manufacturer later added one to the same model. - The court may admit the later change for that limited impeachment purpose, not as proof that the earlier design was defective. Admit the evidence because post-accident design changes are substantive proof that the earlier design was defective. - Under the subsequent-remedial-measures rule, adding a guard after the accident cannot be used to prove a product defect. - The worker offered the change to challenge the supervisor’s testimony, not as substantive proof that the unguarded pinch point was defective. Exclude the evidence because a later safety measure cannot be used for any purpose in a products-liability action. - The rule is not an absolute bar: a subsequent measure may be admitted for a permitted purpose such as impeachment. - Here, the worker identified the supervisor’s statement that a guard was never considered as the testimony to be impeached. Exclude the evidence because later design changes are privileged communications prepared in anticipation of litigation. - Adding a guard is a design change, not a privileged communication. - Nothing in the facts establishes that evidence of the change was prepared in anticipation of litigation.

7. A warehouse worker brought a federal products-liability action against a forklift manufacturer after being struck when the forklift backed over his foot. The worker alleged that the forklift should have included a rear-facing camera system to alert operators to obstacles behind the vehicle. During discovery, the manufacturer asserted that such a camera system could not be reliably installed given the dust and vibration present in typical warehouse environments. Three months after the accident, the manufacturer began selling the same forklift model equipped with a rear-facing camera system rated for dusty, high-vibration conditions. The worker offers the redesigned camera system solely to rebut the manufacturer's feasibility assertion. The manufacturer objects that the redesign was a subsequent remedial measure and also argues that displaying it would unfairly prejudice the jury. Which of the following is the strongest response to the objection?

A. The camera system is inadmissible because post-accident safety changes cannot be used for any purpose.
B. The camera system is admissible because later safety changes are direct evidence that the original forklift was defective.
C. The camera system is admissible to address feasibility because the manufacturer disputed that a workable camera system could be installed.
D. The camera system is inadmissible unless the worker first proves that the manufacturer controlled the warehouse after the accident.

Show answer

Answer: C. The camera system is admissible to address feasibility because the manufacturer disputed that a workable camera system could be installed.

The camera system is admissible to address feasibility because the manufacturer disputed that a workable camera system could be installed. - Federal Rule of Evidence 407 permits a subsequent remedial measure to show feasibility when feasibility is disputed, and the manufacturer claimed a camera could not work reliably in dusty, high-vibration warehouses. - The later camera system addresses that claim; the court must still weigh its probative value against any risk of unfair prejudice under Rule 403. The camera system is inadmissible because post-accident safety changes cannot be used for any purpose. - Rule 407 does not impose an absolute bar: it permits evidence of a later change to show disputed feasibility. - The manufacturer's assertion that a reliable camera could not be installed makes that permitted purpose relevant here. The camera system is admissible because later safety changes are direct evidence that the original forklift was defective. - Rule 407 bars using the post-accident redesign to prove a product defect directly. - The worker instead offers the camera system solely to rebut the manufacturer's claim that installing a workable system was infeasible. The camera system is inadmissible unless the worker first proves that the manufacturer controlled the warehouse after the accident. - Control of the warehouse is not a prerequisite to admitting evidence that the manufacturer later sold the same forklift model with a camera. - The disputed issue is whether such a system could work under warehouse conditions, not who controlled the warehouse after the accident.

8. A customer sued a grocery store after slipping and falling on a wet floor in the produce aisle. The customer alleges that the store's flooring was unreasonably slippery. Two days after the fall, before any government investigation, the store replaced the flooring throughout the entire building with a non-slip surface. At trial, the store disputes both negligence and whether it controlled the produce aisle at the time of the fall but does not dispute that safer, non-slip flooring was technologically feasible. The customer offers evidence of the flooring replacement to prove that the original floor was unreasonably dangerous. The store objects. Which of the following best states how the court should rule?

A. Exclude the evidence because it is offered to prove culpable conduct through a subsequent remedial measure.
B. Admit the evidence because replacing the flooring tends to show that the earlier floor caused the fall.
C. Admit the evidence because the store disputes control of the aisle where the fall occurred.
D. Exclude the evidence under Rule 403 because remedial measures have no permissible evidentiary use.

Show answer

Answer: A. Exclude the evidence because it is offered to prove culpable conduct through a subsequent remedial measure.

Exclude the evidence because it is offered to prove culpable conduct through a subsequent remedial measure. - Replacing the flooring after the fall with a non-slip surface is a subsequent remedial measure because it could have made the fall less likely. - The customer offers it to prove the original floor was unreasonably dangerous, a use Rule 407 prohibits. Admit the evidence because replacing the flooring tends to show that the earlier floor caused the fall. - The replacement may support an inference about the earlier floor, but the customer offers that inference to prove the store’s culpable conduct. - Its relevance does not overcome Rule 407’s exclusion for that purpose. Admit the evidence because the store disputes control of the aisle where the fall occurred. - Control is disputed, and Rule 407 can permit remedial-measure evidence offered to prove control. - The customer instead offers the replacement to prove the original floor was unreasonably dangerous, so that exception does not justify admission for the stated purpose. Exclude the evidence under Rule 403 because remedial measures have no permissible evidentiary use. - Rule 407, not a conclusion that the evidence has no permissible use, governs the customer’s stated offer. - A subsequent measure may be admissible for another disputed purpose, such as control, even though it cannot be used here to prove culpable conduct.

9. A shopper sued a grocery store after a storage shelf collapsed and boxes fell on her. The store denies that the shelf's original support bracket was unsafe and asserts that no sturdier bracket was feasible when the shelf was installed. One week after the accident, the store installed a newly available reinforced bracket on every shelf in the store. At trial, the shopper offers evidence of the installation solely to rebut the store's assertion that adding a reinforced bracket was not feasible. The store objects that evidence of a post-accident safety measure is inadmissible. The store does not dispute ownership or control of the shelf. How should the court rule?

A. Exclude the evidence because a post-accident safety measure cannot be admitted for any purpose in a negligence action.
B. Admit the evidence for the limited purpose of proving feasibility because the store has disputed whether a sturdier bracket was feasible.
C. Admit the evidence as substantive proof that the original bracket was defective because the installation makes that conclusion more probable.
D. Exclude the evidence because feasibility is relevant only when ownership or control of the instrumentality is also disputed.

Show answer

Answer: B. Admit the evidence for the limited purpose of proving feasibility because the store has disputed whether a sturdier bracket was feasible.

Admit the evidence for the limited purpose of proving feasibility because the store has disputed whether a sturdier bracket was feasible. - Federal Rule of Evidence 407 permits evidence of a subsequent remedial measure to prove feasibility when feasibility is disputed, as the store has done here. - The jury may consider the installation for that limited purpose, though the bracket’s being newly available means its later installation does not, by itself, establish availability when the shelf was installed. Exclude the evidence because a post-accident safety measure cannot be admitted for any purpose in a negligence action. - Rule 407 is not an absolute bar: it allows a subsequent measure to prove disputed feasibility. - The shopper offers the storewide bracket installation solely for that permitted purpose, not to prove negligence. Admit the evidence as substantive proof that the original bracket was defective because the installation makes that conclusion more probable. - Rule 407 prohibits using the later installation as proof of defect in the original bracket. - Admitting the evidence for disputed feasibility does not permit the jury to infer defect merely because the store later reinforced its shelves. Exclude the evidence because feasibility is relevant only when ownership or control of the instrumentality is also disputed. - Feasibility and control are separate permissible purposes under Rule 407; both need not be disputed. - The store’s undisputed control of the shelf therefore does not foreclose the shopper’s feasibility argument.

Flashcards: Lay opinion and expert qualification

1. Under FRE 702, what are the five alternative sources of qualification for an expert witness, and what does 'proposition-specific' qualification mean?

Show answer

An expert witness may be qualified by knowledge, skill, experience, training, or education. 'Proposition-specific' means the witness's qualifications must directly relate to the particular testimony being offered, not just a general impressive credential.

2. What are the three requirements for admissible lay opinion testimony under FRE 701?

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The opinion must be rationally based on the witness’s perception, helpful to understanding the testimony or determining a fact in issue, and not based on specialized knowledge within the scope of expert testimony. The witness must therefore be using ordinary observations rather than technical or scientific expertise.

3. Under Rule 703, what are the permissible bases for an expert's opinion, and when may inadmissible underlying facts be disclosed to the jury?

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An expert may base an opinion on facts or data they personally observed, were made aware of, or that experts in the field would reasonably rely on. If the underlying facts are inadmissible, they may be disclosed to the jury only if their probative value in helping the jury evaluate the opinion substantially outweighs their prejudicial effect.

4. Under Rule 702, what four requirements must the proponent of expert testimony demonstrate for reliability, and by what standard of proof?

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The proponent must demonstrate, by a preponderance of the evidence, that: 1) the expert’s specialized knowledge will help the trier of fact; 2) the opinion is based on sufficient facts or data; 3) the testimony is the product of reliable principles and methods; and 4) the expert reliably applied those principles and methods to the facts of the case.

5. What are the 'Three Fast Calls' for evidence admissibility, and which rules do they invoke?

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The 'Three Fast Calls' are: 1) Probability (Rule 401 relevance, including conditional relevance under Rule 104(b)), 2) Prejudice (Rule 403 balancing, especially regarding unfair prejudice), and 3) Trial Cost (Rule 403 balancing, considering confusion, undue delay, or needlessly cumulative evidence).

6. What makes evidence relevant under the Federal Rules of Evidence?

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Evidence is relevant if it has any tendency to make a fact more or less probable than it would be without the evidence, and the fact must be consequential to determining the action. Relevant evidence is generally admissible unless the Constitution, a statute, another rule, or Rule 403 provides otherwise.

7. What is the general rule against character evidence offered to prove conduct?

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Under the majority/FRE rule, character evidence is generally inadmissible when offered solely to prove that a person acted in accordance with that character on a particular occasion. Criminal-case exceptions permit a defendant to offer a pertinent trait and allow the prosecution to rebut it, subject to the applicable victim- and defendant-character rules.

8. When may a court exclude relevant evidence under FRE 403?

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The court may exclude relevant evidence when its probative value is substantially outweighed by a danger of unfair prejudice, confusing the issues, misleading the jury, undue delay, wasting time, or needlessly presenting cumulative evidence. Unfair prejudice means an undue tendency to cause the jury to decide on an improper emotional or otherwise illegitimate basis.

Lay opinion and expert qualification

On this page

The Classification Gate: Perception Ends Where Specialized Knowledge Begins

The Expert’s Reach: Credentials Must Fit the Proposition

A Collision Record: Two Defensible Routes in Six Choices

Three Short Tests: One Rule and One Fact at a Time

High-Yield Points - ⚡ Biggest Takeaways

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Practice Questions: Lay opinion and expert qualification

Flashcards: Lay opinion and expert qualification

Everything you need for Bar Exam prep