Bar Exam (Next Generation) Quiz: Contradiction

12 questions · exam conditions

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ContradictionQuestion 1 of 12

At a murder trial, the prosecution's eyewitness testified that she saw the defendant fire the gun from her apartment window across the street. On cross-examination, she denied defense counsel's suggestion that she had been out of town on the day of the shooting. The defense later calls the building's superintendent to testify that the witness's apartment was being fumigated that day and that the witness had checked into a hotel. The prosecution objects.

Should the superintendent's testimony be admitted?

No, because the defense may not impeach a prosecution witness with extrinsic evidence about a matter the witness denied on cross-examination.

No, because the witness's whereabouts on the day of the shooting is a collateral matter and extrinsic evidence is barred.

Yes, because the witness's presence at the apartment is relevant to her opportunity to observe the shooting, so the matter is not collateral.

Yes, because a party may always impeach a witness with extrinsic evidence when the witness denies a fact on cross-examination.

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Bar Exam (Next Generation) Quiz

Bar Exam (Next Generation) Quiz: Contradiction

Practice Contradiction in Bar Exam (Next Generation) with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Contradiction, giving you a quick way to practice the rules, question types, and explanations that matter most for Bar Exam (Next Generation).

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

Should the superintendent's testimony be admitted?

No, because the defense may not impeach a prosecution witness with extrinsic evidence about a matter the witness denied on cross-examination.
No, because the witness's whereabouts on the day of the shooting is a collateral matter and extrinsic evidence is barred.
Yes, because the witness's presence at the apartment is relevant to her opportunity to observe the shooting, so the matter is not collateral. (correct answer)
Yes, because a party may always impeach a witness with extrinsic evidence when the witness denies a fact on cross-examination.

Explanation: Whenever you see an impeachment question involving extrinsic evidence, your immediate check should be: is the fact collateral? The collateral-matter rule bars a party from introducing outside evidence to contradict a witness on a tangential point that only affects general credibility. But if the fact has independent relevance to the substantive issues in the case, it is not collateral, and extrinsic evidence is admissible. Here, the eyewitness claimed she saw the shooting from her apartment window. Her whereabouts on that day directly affect her opportunity to observe the incident—a substantive element of her testimony, not just a credibility sideshow. If she was actually at a hotel because her apartment was being fumigated, she could not have seen the shooting from that window. Because this fact goes to the heart of her perception, the matter is not collateral, so the superintendent's testimony should be admitted. The first wrong choice—"may not impeach... with extrinsic evidence about a matter the witness denied"—misstates the rule: extrinsic evidence is barred only for collateral denials, not all denials. The second wrong choice—"whereabouts... is a collateral matter"—incorrectly classifies the fact; it ignores that the witness's location is directly relevant to her ability to perceive the event. The final wrong choice—"may always impeach... when the witness denies a fact"—overstates the rule; the word "always" is the trap, because collateral matters remain barred even after a denial. Study tip: For any impeachment question, ask yourself: Does this fact matter to the case beyond just credibility? If yes, it's not collateral, and extrinsic evidence is allowed.

Question 2

In a personal injury action, the plaintiff's sister testified for the defendant. On direct, she said the plaintiff told her she had not been injured. On cross, plaintiff's counsel asked whether she was biased against the plaintiff and whether she had recently asked the plaintiff for money and been refused. The sister denied both. Plaintiff later calls a family friend to testify that the sister and plaintiff are close and that the sister complained about the refusal two weeks ago.

Should the family friend's testimony be admitted?

No, because the sister denied bias on cross-examination and the plaintiff is bound by her answer.
No, because the family friend's testimony about the sister's statement is hearsay not within any exception.
Yes, because the testimony is a prior inconsistent statement, and extrinsic evidence of a prior inconsistent statement is admissible even if the matter is collateral.
Yes, because evidence of bias is not collateral and may be proved by extrinsic evidence even after the witness denies it. (correct answer)

Explanation: When you see a witness deny something on cross and the opponent wants to call another witness to contradict that denial, the central question is whether the matter is collateral. A matter is collateral if it is irrelevant to the case except for impeachment. Bias, however, is never collateral—it is always directly relevant to the witness's credibility. Here, the sister denied being biased and denied asking for money. The family friend's testimony about her complaint directly proves a motive to testify falsely: resentment over the refused loan. Because bias is a non-collateral matter, extrinsic evidence is admissible to prove it, even after the witness denies it. That is why the correct choice is the one saying "evidence of bias is not collateral and may be proved by extrinsic evidence." Now look at the distractors. The choice saying "the plaintiff is bound by her answer" reflects a common trap—you are bound by a witness's denial only on collateral matters, and bias is not collateral. The "hearsay" choice fails because the friend's testimony about the complaint is offered to show bias (a non-hearsay purpose), not to prove the truth of the complaint itself. The "prior inconsistent statement" choice is doubly wrong: the friend's testimony is not a prior inconsistent statement of the sister about the injury, and extrinsic evidence of a prior inconsistent statement is admissible only for non-collateral matters—the opposite of what that choice states. Study tip: memorize the short list of non-collateral impeachment subjects—bias, motive, capacity, and prior convictions. If a question tests any of these, extrinsic evidence is always allowed.

Question 3

In a criminal trial, a prosecution witness testified on direct that she had never been convicted of a crime. On cross, defense counsel asked whether she had been convicted of perjury five years ago. She denied it. Defense later offers a certified copy of the judgment of conviction.

Should the court admit the judgment?

Yes, because a prior felony conviction is admissible to impeach and may be proved extrinsically to contradict the denial. (correct answer)
No, because a prior conviction is a specific instance of conduct that may not be proved by extrinsic evidence.
No, because a witness's denial on cross-examination is conclusive unless the matter is independently admissible.
Yes, because the witness's volunteered statement on direct makes all contradictory evidence admissible.

Explanation: Whenever you see a witness impeachment question involving a prior conviction, your first thought should be Rule 609 and the "collateral matter" doctrine. The key is distinguishing a specific instance of conduct (usually barred from extrinsic proof) from a conviction (an independently admissible fact). Here, the witness's perjury conviction is a felony and a crime of dishonesty, making it admissible to impeach under Rule 609. Because it is independently admissible, it is not collateral—so when she denied it on cross, defense counsel may prove it extrinsically with the certified judgment. This is the correct outcome. The choice claiming "a prior conviction is a specific instance of conduct that may not be proved by extrinsic evidence" is a classic trap: Rule 608(b) bars extrinsic evidence for specific instances, but Rule 609 creates a specific exception for convictions. The choice stating "a witness's denial on cross-examination is conclusive unless the matter is independently admissible" gets the rule backwards—the denial is not conclusive because the matter is independently admissible. Finally, the choice saying "the witness's volunteered statement on direct makes all contradictory evidence admissible" overstates the "opening the door" doctrine; admissibility here rests on the conviction's independent admissibility, not on the volunteered statement. Study tip: memorize the short list of non-collateral matters provable extrinsically—bias, motive, prior convictions, and reputation/opinion for truthfulness. Everything else is barred.

Question 4

In a fraud trial, a defense witness testified that the plaintiff had a poor reputation for honesty. On cross, plaintiff's counsel asked the witness whether she had falsified expense reports at her last job and been fired for doing so. The witness denied it. Plaintiff later calls the witness's former supervisor to testify that the witness was fired for falsifying expense reports.

Is the supervisor's testimony admissible?

Yes, because the witness's denial on cross-examination permits the plaintiff to prove the matter extrinsically.
Yes, because falsifying expense reports is probative of the witness's character for truthfulness.
No, because the witness's character for truthfulness may not be attacked with specific instances of conduct.
No, because specific instances of conduct not resulting in a conviction may not be proved by extrinsic evidence. (correct answer)

Explanation: When you see a question about impeaching a witness with prior bad acts, remember the critical distinction between cross-examination and extrinsic evidence. Under Rule 608(b), specific instances of conduct that are probative of truthfulness (like lying or falsifying documents) may be inquired into on cross-examination, but if the witness denies the act, the cross-examiner is stuck with that denial—you cannot call outside witnesses to prove the act happened. Here, the defense witness testified about the plaintiff's poor reputation for honesty, opening the door to her own character for truthfulness being attacked. The plaintiff's counsel properly asked about the falsified expense reports on cross. However, when the witness denied it, the plaintiff's attempt to call the former supervisor to prove the act fails. The supervisor's testimony would be extrinsic evidence of a specific instance of conduct that did not result in a conviction, which is expressly prohibited by Rule 608(b). Now examine the wrong choices. The first wrong choice suggests the denial permits extrinsic proof—that is a classic trap; a denial does not waive the extrinsic evidence bar. The second wrong choice notes the conduct is probative of truthfulness, which is true, but probative value only allows the cross-examination, not the outside proof. The third wrong choice claims character for truthfulness may not be attacked with specific instances at all, which is false—they can be raised on cross, just not proven extrinsically. Strategy tip: Memorize the mantra for 608(b)—"ask, don't prove." If the act didn't result in a conviction, you may ask about it on cross, but you cannot bring in extrinsic evidence, even if the witness lies.

Question 5

In a traffic-accident case, a witness testified for the defendant that the plaintiff's car ran a red light. On cross-examination, plaintiff's counsel asked whether she had told a police officer at the scene thatthe light was yellow. The witness denied it. Plaintiff later calls the police officer to testify thatthe witness told him the light was yellow.

Is the officer's testimony admissible?

Yes, becauseethe witness was given an opportunity to deny the statement and it is inconsistent with her trial testimony. (correct answer)
No, because the prior statement was not made under oath and cannot be used either substantively or for impeachment.
No, because the officer's testimony is hearsay and may not be used for impeachment.
Yes, because a prior inconsistent statement may always be admitted as substantive evidence.

Explanation: When you see a prior statement by a witness being offered after the witness has testified, think impeachment: a witness's credibility can be attacked with a prior inconsistent statement, even if that statement would otherwise be hearsay. Here, the witness denied telling the officer the light was yellow, and the officer's testimony that she did say it is directly inconsistent with her trial testimony. Because the witness was given the opportunity to deny or explain the statement on cross-examination, the officer may testify about it — but only to impeach the witness's credibility, not to prove the light was actually yellow. The correct answer is the one that says it is admissible because the witness had the opportunity to deny the statement and it is inconsistent with her trial testimony. Now the wrong answers. "No, because the prior statement was not made under oath and cannot be used either substantively or for impeachment" confuses two rules: lack of oath prevents substantive use, but it does not prevent impeachment. "No, because the officer's testimony is hearsay and may not be used for impeachment" mistakes the purpose—impeachment evidence is not offered for the truth of the matter, so the hearsay rule does not exclude it. "Yes, because a prior inconsistent statement may always be admitted as substantive evidence" overstates the rule; most unsworn prior inconsistent statements are admissible only for impeachment, not as substantive proof. Study tip: distinguish "impeachment" (credibility) from "substantive" (truth). If a prior inconsistent statement is unsworn, it can still attack credibility—just not prove the fact itself.

Question 6

In a shoplifting prosecution,ethe security guard testified for the State that she saw the defendant hide merchandise and leave the store, and thatthe defendant was wearing a blue coat. The defendant's identity is not disputed. On cross-examination, defense counsel asked whether she had told the store manager the day before trial thatthe defendant's coat was black. The guard denied it. Defense later calls the store manager to testify thatthe guard made that statement.

Is the manager's testimony admissible?

Yes, becauseethe guard was given an opportunity to deny the statement andethe testimony is offered only to impeach her credibility.
No, becauseethe color of the defendant's coat is collateral and may not be proved by extrinsic evidence. (correct answer)
Yes, becauseethe guard's statement to the manager is an opposing party's statement and is not hearsay.
No, because a witness may not be impeached by a prior statement about a fact not in issue.

Explanation: When you see a prior inconsistent statement offered to impeach a witness, separate the cross-examination itself from the extrinsic proof. A witness may be asked about a prior denial on cross, but you may not bring in outside witnesses to prove a prior statement if the subject is merely collateral. Here, the store manager's testimony is extrinsic evidence of what the guard allegedly said about the coat. Because the defendant's identity is undisputed, the coat's color is not centrally relevant to any issue in the case—it is collateral. Once the guard denied making the statement, the defense was bound by that answer; it cannot call the manager to prove the statement for impeachment. The "opportunity to deny" choice is tempting because foundation is required, but foundation alone does not make collateral extrinsic evidence admissible. The "opposing party's statement" choice is wrong because the guard is a witness, not a party, and the statement is not offered for its truth anyway. The "may not be impeached by a prior statement about a fact not in issue" choice captures the right outcome but misstates the rule: a witness can be impeached on cross about collateral matters; the limitation is on proving them with outside witnesses. Study tip: whenever you see extrinsic evidence offered to impeach, ask first, "Is this fact truly at issue?" If not, the witness's denial ends the matter.

Question 7

In a personal-injury action,ethe plaintiff claims the defendant's negligence caused his back injury. W testifies for the defense that she frequently saw the plaintiff lifting heavy boxes after the accident. On cross-examination,ethe plaintiff's attorney asks W whether she is the defendant's sister and has lived atthe defendant's house for the past two years. W denies both. The plaintiff later calls the defendant's mother to testify that W is the defendant's sister and has lived atthe defendant's house for two years.

The mother's testimony is:

Inadmissible, because Rule 608(b) bars extrinsic evidence of specific instances of a witness's conduct when offered to attackethe witness's credibility for truthfulness.
Admissible, because W's family relationship and living arrangement with the defendant are noncollateral matters bearing on bias, and after W denied themethe plaintiff may use extrinsic evidence to prove bias and impeach W's credibility. (correct answer)
Inadmissible, because W's family relationship and living arrangement are collateral toethe plaintiff's claim, soethe plaintiff is bound by W's denial on cross-examination.
Admissible, because a witness who denies a fact on cross-examination may always be contradicted by extrinsic evidence, andethe mother has personal knowledge of the fact.

Explanation: Whenever you see a question about impeaching a witness, separate the three main grounds: character for truthfulness, prior inconsistent statements, and bias. Bias is special — it is almost never collateral, so extrinsic evidence is generally allowed once the witness denies it. Here, the plaintiff wants to show W is the defendant's sister and lives with him. That matters because it suggests W is biased toward the defense. Bias is a noncollateral matter bearing directly on credibility. Because W denied the relationship and living arrangement on cross-examination, the plaintiff may prove those facts through the defendant's mother. That is exactly why the correct answer is the one recognizing the bias exception. The answer invoking Rule 608(b) misunderstands the issue: that rule bars extrinsic evidence of prior bad acts to attack character for truthfulness, but this is bias, not character. The answer saying the facts are collateral gets it backwards — bias is a noncollateral matter, so the plaintiff is not bound by W's denial. Finally, the answer claiming a witness may "always" be contradicted by extrinsic evidence is too broad; only noncollateral matters, like bias, may be proved after denial, not every incidental detail. On exam day, when you see a witness denied something on cross and later evidence contradicts her, ask: "Does this go to bias, motive, or a substantive issue?" If yes, extrinsic evidence is admissible. Bias is the great exception to the collateral rule.

Question 8

In a civil battery action, the defendant's neighbor testified that she saw the defendant punch the plaintiff. She volunteered on direct that she remembered the date because it was the day her son returned from military service. The plaintiff later offers a travel itinerary showing that the son returned two weeks after the battery. The plaintiff says the itinerary undermines the neighbor's memory.

Is the itinerary admissible?

Yes, because the neighbor opened the door to the contradiction by volunteering the statement on direct examination.
Yes, because evidence that a witness has an inaccurate memory is always relevant to credibility.
No, because the date of the son's return is collateral and may not be proved by extrinsic evidence. (correct answer)
No, because a witness may not be impeached on a matter she raised during her own direct testimony.

Explanation: Whenever you see evidence offered to challenge a witness's memory, your first instinct should be to check the collateral evidence rule. A fact is "collateral" if it has no independent relevance to the substantive issues in the case. Here, the battery hinges on whether the defendant punched the plaintiff, not on when the neighbor's son returned home. The itinerary merely attacks the neighbor's general recollection of the date, making the date a collateral matter. While you may cross-examine a witness on collateral details to test credibility, you are bound by her answer—you may not introduce extrinsic evidence, such as this travel itinerary, to contradict her on a point that is purely collateral. The argument that the neighbor "opened the door" by volunteering the statement on direct fails because opening the door simply allows cross-examination on that topic, but it does not waive the collateral rule's prohibition on extrinsic proof. Similarly, the claim that inaccurate memory is "always relevant to credibility" is a trap—credibility is always relevant, but the method of proving it is strictly limited by the collateral doctrine. Finally, the assertion that a witness may not be impeached on a matter she raised on direct is backwards; you absolutely can, but the extrinsic evidence ban still applies regardless of who raised the issue. Remember this pattern: if the fact you want to prove is not itself a fact of consequence to the lawsuit, it is collateral—so ask on cross, but leave your exhibits at the counsel table.

Question 9

In a wrongful-death action, the plaintiff called the only eyewitness, expecting her to testify that the decedent was in the crosswalk. Instead, the witness testified that the decedent ran into the street outside the crosswalk. The plaintiff later seeks to introduce a surveillance video from a nearby store showing the decedent in the crosswalk.

Is the video admissible?

No, because a party may not impeach its own witness unless the witness is surprised or hostile.
No, because the video is extrinsic evidence offered on a collateral matter and the plaintiff is bound by the witness's testimony.
Yes, because the witness's testimony was adverse, so the plaintiff may treat her as a hostile witness.
Yes, because any party, including the plaintiff, may attack a witness's credibility by contradiction. (correct answer)

Explanation: Whenever you see a question about impeaching your own witness, remember that the old "voucher rule" is dead. Under the Federal Rules, any party—including the plaintiff—may attack any witness's credibility, subject only to genuine surprise or affirmative damage. Here, the witness gave testimony harmful to the plaintiff's case, but "adverse" doesn't automatically make her hostile. The real issue is whether a prior inconsistent statement can be proved by extrinsic evidence. The video directly contradicts the witness's in-court statement about where the decedent was. Because that statement concerns a material fact—the decedent's location in a wrongful-death action—it is not collateral, so extrinsic evidence is allowed to impeach. The correct answer is "Yes, because any party, including the plaintiff, may attack a witness's credibility by contradiction." That rule applies directly: the video is a classic prior inconsistent statement on a non-collateral matter. Now the wrong answers. "No, because a party may not impeach its own witness unless the witness is surprised or hostile" is a common trap—it reflects the old voucher rule that Rule 607 abolished. Surprise and hostility matter only for a party's own witness under Rule 607, but here the video isn't being used to show bias or incapacity; it's contradiction. "No, because the video is extrinsic evidence offered on a collateral matter" fails because location of the decedent is a central issue, not collateral. "Yes, because the witness's testimony was adverse, so the plaintiff may treat her as a hostile witness" mislabels the concept—"adverse" under Rule 607 is not the same as "hostile" for leading questions; the video's admissibility doesn't depend on hostility. Study tip: When you see impeachment by prior inconsistent statement, ask two things—is it a material issue, and is the witness available to explain? If material, extrinsic evidence is admissible.

Question 10

In an age-discrimination suit,ethe plaintiff testified that she was fired because of her age and that she had never received a negative performance review. On cross, she denied that she had ever received a written warning. The employer, whose defense is thatthe plaintiff was fired for poor performance, later offers a signed written warning from her personnel file accompanied by evidence establishing thatthe warning was made and kept in the regular course of the employer's business, stating that she failed to meet sales quotas for three consecutive months.

Is the written warning admissible?

No, because specific instances of conduct may not be proved by extrinsic evidence to attack a witness's character for truthfulness.
Yes, becauseethe warning is independently admissible to proveethe employer's asserted reason for the dischargeeand may also contradictethe plaintiff's testimony. (correct answer)
No, becauseethe plaintiff's employment record is collateral toethe age-discrimination claim andethe plaintiff denied receivingethe warning.
Yes, becauseethe plaintiff's denial on cross-examination openedethe door to any extrinsic evidence.

Explanation: Whenever you see a document offered in an employment case, ask two questions: Is it independently relevant to a claim or defense? And does a hearsay exception apply? Here both answers are yes. The signed warning from the personnel file, with a proper business-records foundation, is admissible under the business records exception. It is also substantively relevant: the employer's defense is poor performance, and the warning—stating three months of missed sales quotas—tends to prove that asserted nondiscriminatory reason. Because the warning is independently admissible for that purpose, it is not collateral, and it may additionally be used to contradict the plaintiff's denial on cross-examination. The warning is admissible. The "specific instances of conduct" objection misunderstands Federal Rule of Evidence 608(b): that rule bars extrinsic evidence when offered only to attack a witness's character for truthfulness. Here the warning is offered to prove the employer's actual reason for firing, not merely to show the plaintiff is dishonest. So independent relevance defeats that objection. The "employment record is collateral" argument is also wrong: when the employer's defense is poor performance, a warning from the personnel file is directly relevant to the central issue, not collateral. The "denial opened the door to any extrinsic evidence" statement goes too far: cross-examination does not automatically make any extrinsic evidence admissible; the warning is admissible because it is independently relevant, not because the defendant "opened the door" to everything. Study tip: always separate "impeachment oncollateral matters" from"independent substantive relevance." If a document is relevant to a real claim or defense, it can come in even if it also hurts credibility; the collateral-evidence bar only applies when the evidence has no other purpose.

Question 11

At trial, a plaintiff's witness testified that she saw the defendant's car swerve into the plaintiff's lane. After she stepped down,ethe defendant learned thatthe witness had told a friend the day after the accident that she had not actually seen the collision and had assumed the defendant swerved. The witness remains in the courthouse and is available to be recalled. The defendant does not ask to recall her and instead calls the friend to testify about the statement.

Should the friend's testimony be admitted?

No, becauseethe witness was not given an opportunity to explain or deny the statement and no exception applies. (correct answer)
No, becauseethe statement was made to a friend and is therefore hearsay not within any exception and may not be used to impeach.
Yes, becauseethe statement is a prior inconsistent statement that is material to the witness's credibility.
Yes, because a party may use any contradictory evidence to impeach a witness who has completed her testimony.

Explanation: When you see an impeachment question involving a prior statement, think about two distinct issues: is the statement really inconsistent, and may you introduce it through another witness? Under the rules, a party may impeach a witness with a prior inconsistent statement, but if the witness is available, the witness ordinarily must first be confronted with the statement and given an opportunity to explain or deny it. Extrinsic evidence—like calling the friend here—is not allowed without that foundation unless justice otherwise requires. Here, the witness is still in the courthouse and could be recalled, but the defendant never gave her that chance. The correct answer is therefore that the friend's testimony should be excluded because the witness was not given an opportunity to explain or deny the statement and no exception applies. The "statement was made to a friend and is therefore hearsay" choice is wrong because a prior inconsistent statement offered only to impeach credibility is not hearsay; its purpose is not to prove the truth of what was said. The "prior inconsistent statement that is material" choice identifies an accurate detail, but materiality alone does not cure the missing foundation. Finally, the "any contradictory evidence" choice is too broad—impeachment by extrinsic evidence is limited by procedural rules, especially when the witness can be questioned about the statement directly. Study tip: on evidence questions involving prior inconsistent statements, always check whether the witness has been given the required chance to explain or deny before jumping to admissibility.

Question 12

In a negligence action, an expert witness testified that she had been a licensed architect for ten years and was qualified to testify about building-code standards. On cross-examination, she denied that her license had ever been suspended. The opposing party later offers a state licensing board order showing that her license was suspended for two years during that period.

Is the licensing board order admissible?

No, because a license suspension is a specific instance of conduct that may not be proved by extrinsic evidence.
No, becauseethe suspension is collateral toethe issues in the negligence action andethe witness denied it on cross-examination.
Yes, because an expert's qualifications are relevant to credibility and are not collateral. (correct answer)
Yes, becauseethe licensing board order is a prior inconsistent statement under oath.

Explanation: Whenever a witness denies something on cross-examination and the other side wants to introduce outside evidence to contradict that denial, ask: is this matter collateral? If it is collateral, the answer on cross is final and extrinsic evidence is barred. But an expert's professional credentials are not collateral—they go directly to the witness's qualifications and therefore to the weight and credibility of her opinion. Here, the witness claimed to be a licensed architect for ten years, then denied any suspension. The licensing board order directly undermines her claimed qualifications, so it is relevant and admissible. The ban on extrinsic evidence for specific instances of conduct applies to acts offered to show a witness's character for truthfulness, such as prior fraud. The license suspension is not offered that way; it attacks the foundation of her expert testimony. The "collateral" objection fails for the same reason—qualifications are central, not side details. And although the order contradicts her denial, it is not a prior inconsistent statement under oath made by the witness; it is an official record, not her own sworn statement. Strategy tip: separate "impeaching a witness's character for truthfulness" from "challenging an expert's qualifications." The former generally cannot be proved by extrinsic evidence; the latter can. When evidence attacks expertise, bias, or capacity, it is usually noncollateral and admissible.