Lake v. State: Late-Disclosed Impeachment Evidence During Trial Is Not Brady “Suppression,” and Child-Witness Competency Turns on Mental Ability, Not Detailed Recall

Introduction

In Justin Scott Lake v. State of Wyoming, 2025 WY 99 (Sept. 12, 2025), the Wyoming Supreme Court affirmed convictions for one count of first-degree sexual abuse of a minor and four counts of second-degree sexual abuse of a minor. The case squarely presented two recurring trial issues in child sexual abuse prosecutions: (1) the competency of young victims to testify, and (2) whether a late-disclosed forensic interview of a potential third victim triggered a Brady/Giglio violation requiring a mistrial. The Court held that the district court did not abuse its discretion in finding the children competent and, further, that the State’s mid-trial disclosure of a follow-up interview—paired with the court’s opportunity for the defense to use it and curative measures for a nonresponsive volunteered statement—did not constitute “suppression” under Brady or warrant a mistrial.

This opinion clarifies two practical points: trial courts need not prolong competency inquiries when the record supports a child’s mental ability to form and relay memories, and delayed disclosure does not amount to Brady suppression if the defense can still make meaningful use of the material during trial. It also underscores that a volunteered, nonresponsive reference to uncharged conduct can be adequately cured through striking and instruction.

Summary of the Opinion

Child-witness competency: The district court properly found the two minor victims, IB and TL, competent to testify. Applying the five-part Larsen test and Young, the Court emphasized that the third factor concerns mental ability to retain an independent recollection, not the witness’s ability to recall every specific detail. The court did not abuse its discretion in declining additional defense-requested questions during the competency hearing (¶¶ 14–20).
Brady/Giglio and mistrial: The State’s mid-trial disclosure of a follow-up forensic interview of JL did not violate Brady because it was disclosed in time for the defense to use it, and the district court offered the defense the opportunity to recall or call witnesses (¶¶ 25–27). Even assuming favorability, the materiality showing failed: the interview’s impeachment value was cumulative, and its corroborative aspects cut against materiality (¶¶ 28–33). The district court’s remedy—striking a nonresponsive volunteered statement and instructing the jury to disregard it—was sufficient; denying a mistrial was not an abuse of discretion (¶¶ 34–35).

Detailed Analysis

Precedents Cited and Their Role

W.R.E. 601: The rule presumes every person competent to testify unless otherwise provided. Competency is the rule, not the exception (¶ 15).
Larsen v. State, 686 P.2d 583 (Wyo. 1984): Establishes the five-part competency test for child witnesses: truthfulness, capacity to receive an accurate impression, memory for independent recollection, ability to express memory, and capacity to understand simple questions (¶ 16).
Young v. State, 2018 WY 53, 418 P.3d 224: Clarifies that competency turns on mental ability, not age; the third Larsen factor focuses on capacity, not perfect memory of specifics. Credibility concerns are for cross-examination (¶¶ 15–19).
Gruwell v. State, 2011 WY 67, 254 P.3d 223; Griggs v. State, 2016 WY 16, 367 P.3d 1108: Reinforce that competency is distinct from credibility and that cross-examination is the proper vehicle to test credibility (¶ 17).
Triplett v. State, 2017 WY 148, 406 P.3d 1257; King v. State, 2023 WY 36, 527 P.3d 1229; McGill v. State, 2015 WY 132, 357 P.3d 1140: Frame mistrial as an “extreme and drastic” remedy; trial courts assess whether prejudice is so severe that justice cannot proceed. Appellate courts examine severity, pervasiveness, and curative measures (¶¶ 13, 22).
Brady v. Maryland, 373 U.S. 83 (1963) and Giglio v. United States, 405 U.S. 150 (1972): Require disclosure of exculpatory and impeachment evidence. Wyoming applies a three-part test: suppression by the State, favorability, and materiality (reasonable probability of a different result) (¶¶ 23–24).
Mills v. State, 2023 WY 76, 533 P.3d 182; Lawson v. State, 2010 WY 145, 242 P.3d 993; Pearson v. State, 2017 WY 19, 389 P.3d 794: Recent Wyoming authority synthesizing Brady/Giglio standards (¶¶ 23–24).
Thomas v. State, 2006 WY 34, 131 P.3d 348; Whitney v. State, 2004 WY 118, 99 P.3d 457: Delayed disclosure is not suppression where disclosure occurs early enough for effective use at trial (¶ 25).
Chauncey v. State, 2006 WY 18, 127 P.3d 18; Relish v. State, 860 P.2d 455 (Wyo. 1993): Cumulative impeachment evidence is generally not material under Brady (¶ 32).
Kyles v. Whitley, 514 U.S. 419 (1995): Materiality asks whether nondisclosure undermines confidence in the verdict (¶ 28).
Salinas v. State, 2016 WY 97, 380 P.3d 647: A single volunteered, nonresponsive statement can be cured by striking and instruction without requiring a mistrial (¶ 34).
Kovach v. State, 2013 WY 46, 299 P.3d 97: De novo review of constitutional questions (¶ 13).

Legal Reasoning Applied to the Facts

1) Child-Witness Competency

The defense sought additional competency hearing questions aimed at probing the children’s memory of events surrounding the alleged abuse to test their capacity for independent recollection (third Larsen factor). The district court declined, having already questioned the children and found them competent. The Supreme Court affirmed, emphasizing:

The third Larsen factor assesses the child’s mental ability to retain an independent recollection, not whether she can remember every contextual detail (¶ 17). The inability to recall certain specifics affects credibility, not competency.
The record showed both IB and TL had adequate mental capacity: they recalled contemporaneous life events (birthdays, holidays, favorite subjects, current and prior grades and teachers) and temporal context relative to the abuse (¶ 18). Some gaps (e.g., address, duration at residence) go to credibility.
Defense later used inconsistencies elicited at trial to challenge credibility, demonstrating that the adversarial process—not expanded competency probing—was the correct forum for those disagreements (¶ 19).

The Court’s deference to the trial judge’s vantage point—observation of demeanor, tone, and manner nuances—tracked its precedent cautioning against second-guessing competency on a cold appellate record (¶ 12).

2) Brady/Giglio and Mistrial

The controversy arose when a forensic interviewer, asked whether other girls had disclosed abuse, volunteered that JL “had a follow-up interview where she had made disclosures of attempts.” The State had not previously disclosed JL’s follow-up interview or a related email from the detective. The district court struck that testimony, instructed the jury to disregard it without repeating the content, ordered immediate production of the interview, and permitted the defense to recall or call any witnesses (¶¶ 9–10).

a) No Brady Suppression

Suppression under Brady hinges on nondisclosure until it is too late for meaningful use. Here, disclosure on the second trial day, coupled with the court’s offer to reopen witness examinations and call JL, afforded the defense an opportunity to use the material (¶¶ 25–27). Relying on Thomas and Whitney, the Court held that such mid-trial disclosure is not suppression; due process is satisfied when the defense can deploy the evidence in cross, closing, or other parts of the case.

b) Favorability and Materiality

Even putting the suppression prong aside, the Court found no materiality. The defense argued the interview would have changed cross-examination, particularly via a statement that IB had told JL, “You should watch out for your dad, he’s touching me” (¶¶ 29–31).

Cumulative impeachment: The defense already impeached IB and TL with inconsistencies; one more impeachment piece would have been “at best cumulative” (Chauncey; Relish) and insufficient to render the verdict unworthy of confidence (¶ 32).
Mixed (and even inculpatory) content: JL’s statements corroborated aspects of IB/TL’s accounts and included inculpatory details about IB and TL, undercutting any claim that earlier disclosure would probably have altered the verdict (¶¶ 30–31).
Strategic choice: The district court invited the defense to use the interview by recalling IB or calling JL; the defense elected not to. The Court emphasized that the jury’s assessment still turned on IB and TL’s credibility about the charged conduct, not speculation about uncharged acts involving JL (¶ 33).

c) Denial of Mistrial Was Within Discretion

Under the stringent mistrial standard, the district court was best positioned to evaluate prejudice. It:

Identified the volunteered statement as nonresponsive to the prosecutor’s question (¶ 34).
Struck the statement and gave a cautionary instruction without re-highlighting the content (¶ 10).
Facilitated defense use of the late-disclosed interview by reopening the defense’s ability to call or recall witnesses (¶ 9).

Consistent with Salinas, the Court presumed the jury followed the instruction and concluded justice could proceed without a mistrial (¶ 34).

Impact and Implications

1) Competency Hearings for Child Witnesses

The opinion fortifies trial courts’ discretion to limit competency inquiries to what is necessary to evaluate the Larsen factors, especially the third factor’s focus on mental ability rather than granular recollection. Litigants should be prepared that requests for expansive temporal probing may be denied where the record shows sufficient cognitive capacity.
Defense counsel should separate competency arguments (capacity) from credibility attacks (inconsistencies), reserving the latter for cross-examination at trial.

2) Brady/Giglio and Mid-Trial Disclosures

The Court reiterates a pragmatic rule: late disclosure is not “suppression” if the defense can still make use of the evidence during trial. Trial courts can cure timing issues by granting continuances, recalling witnesses, or reopening proofs—a toolkit that can preserve convictions while protecting due process.
Prosecutors should still view early disclosure as best practice. Even when charges are not pursued for a potential victim, related interviews that bear impeachment or corroborative value in the charged case should be reviewed and disclosed in time to be useful.
Defense counsel must be prepared to pivot: when a court offers the opportunity to recall witnesses to exploit late-disclosed material, declining to do so will complicate any later claim of prejudice.

3) Handling Volunteered, Nonresponsive Testimony About Uncharged Conduct

The opinion confirms that a single, volunteered, nonresponsive reference to uncharged misconduct (here, attempted abuse involving JL) can be effectively cured by striking and instruction, without necessitating a mistrial (Salinas line of authority).
Practically, counsel should narrowly frame questions when eliciting forensic interview histories and should be prepared to request immediate curative measures if a witness strays into 404(b)-adjacent territory.

Complex Concepts Simplified

Competency vs. credibility: Competency asks whether a witness has the mental capacity to understand, recall, and communicate truthfully; credibility asks whether the factfinder should believe them. A child can be competent even with imperfect memory. Credibility is tested by cross-examination.
Third Larsen factor (“independent recollection”): Focuses on the child’s mental ability to form and hold memories, not an exacting recall of every surrounding detail.
Brady and Giglio: The State must disclose evidence favorable to the defense (exculpatory or impeaching). To prove a violation, the defendant must show suppression, favorability, and materiality (a reasonable probability of a different result).
Suppression vs. delayed disclosure: Disclosure during trial is generally not suppression if the defense can still use the evidence (through cross, calling witnesses, or argument).
Materiality: Evidence is material if its absence undermines confidence in the verdict. Cumulative impeachment usually is not material.
Curative instruction: When a jury is instructed to disregard stricken testimony, courts presume the jury follows the instruction, which commonly cures isolated, nonresponsive statements.
Abuse of discretion: A deferential standard. The appellate question is whether the trial court could reasonably conclude as it did and whether it acted non-arbitrarily, recognizing the trial judge’s superior vantage point.

Conclusion

Lake reinforces two bedrock trial principles in Wyoming. First, under W.R.E. 601 and Larsen, a child’s competency depends on mental ability, not the perfection of recall, and trial courts retain wide discretion to cabin competency inquiries accordingly. Second, Brady/Giglio claims falter where disclosure occurs early enough for the defense to use the evidence at trial; cumulative impeachment rarely meets the materiality threshold. On the mistrial question, the decision confirms that isolated, volunteered references to uncharged conduct can be adequately addressed by striking and instructing the jury.

The opinion offers clear guidance to trial courts managing competency hearings and discovery disputes in sensitive child-abuse prosecutions. For practitioners, it underscores the importance of (1) distinguishing capacity from credibility; (2) promptly exploiting late-disclosed materials when courts reopen proofs; and (3) employing precise questioning to avoid uninvited 404(b)-type disclosures. The verdicts stand, and the governing principles are clarified for future cases.