Unsubstantiated Third‑Party Abuse Allegations Are Generally Irrelevant Under Rule 412(b)(1)(C); Tenth Circuit Reaffirms Strict Foundations for Impeachment by Prior Inconsistent Statements

Introduction

This commentary analyzes the Tenth Circuit’s decision in United States v. Asbill (No. 24-7052, Sept. 3, 2025), an “order and judgment” affirming the defendant’s convictions for sexual abuse. Although nonprecedential, the decision carries persuasive authority and offers concrete guidance on two recurrent trial issues in child sexual abuse prosecutions:

• When, if ever, a defendant may use a child complainant’s alleged prior sexual victimization by someone else to impeach or explain away the charged allegations under Federal Rule of Evidence 412’s constitutional-rights exception; and
• How strictly courts will enforce the foundational requirements for impeachment by prior inconsistent statements under Rule 613(b), especially where the alleged inconsistency involves a child’s forensic interview or prior sworn testimony.

The case arose from the defendant’s efforts to cross-examine the child victim about (i) an Oklahoma DHS report reflecting an unsubstantiated allegation that her brother touched her at a family reunion, (ii) alleged inconsistencies between her trial testimony and prior statements, and (iii) whether the defendant gave her a gun during a hunting trip surrounding the charged hotel assault. The district court limited several lines of cross-examination; the Tenth Circuit affirmed, holding there was no evidentiary or constitutional error.

Summary of the Judgment

• Rule 412 ruling affirmed: The court upheld exclusion of cross-examination into the DHS report of other alleged abuse because (a) the allegation was unsubstantiated; (b) its factual content was materially different from the charged conduct; and (c) admitting it risked a confusing “mini-trial” about an unrelated perpetrator. The constitutional-rights exception in Rule 412(b)(1)(C) did not apply because the defense failed to show relevance and materiality (e.g., bias, motive to lie, or necessary alternative source of sexual knowledge).
• Prior inconsistent statements: The court affirmed the trial judge’s curbs on impeachment because the defense repeatedly failed to lay the required foundation showing an actual inconsistency between trial testimony and prior statements (DHS interview, preliminary hearing). A claim of “I don’t remember my prior testimony” is not, by itself, an inconsistency about the underlying events.
• Gun testimony: There was no exclusion of the fact that the defendant gave the child a gun; the court only sustained an objection to additional questions (e.g., whether she shot it) for lack of relevance.
• Standards of review: Evidentiary limits on cross-examination were reviewed for abuse of discretion; constitutional claims were reviewed de novo. No error was found; convictions were affirmed.

Factual Background and Procedural Posture

The defendant, after living with his girlfriend and her children (including T.C.), maintained contact with T.C. following the relationship’s end. In November 2018, around T.C.’s tenth birthday, he took her on a hunting trip and stayed in a hotel where, according to T.C., he sexually assaulted her. The allegations came to light the next year. A federal grand jury charged multiple counts related to abuse in Indian country; the jury convicted solely on the hotel incident and acquitted on counts tied to earlier alleged abuse. The district court imposed a life sentence and five years of supervised release.

Pretrial, the defense sought to use an Oklahoma DHS report noting an unsubstantiated allegation that T.C.’s brother attempted to put his hands down her shorts at a family reunion months before the charged hotel assault. The district court excluded the DHS-material cross-examination under Rule 412. At trial, the defense endeavored to impeach T.C. with a prior forensic interview and a four-page excerpt from a state preliminary-hearing transcript; the court sustained several objections for improper impeachment. The defense also asked whether T.C. had been given and had shot a gun during the hunting trip; the court allowed the “given a gun” fact but sustained a relevance objection to whether she shot it.

Analysis

Precedents Cited and Their Influence

• Rule 412 and constitutional exception:
  • United States v. A.S., 939 F.3d 1063 (10th Cir. 2019) – The Tenth Circuit emphasized that the constitutional-rights exception to Rule 412(b)(1)(C) is narrowly construed and is generally limited to evidence showing bias or motive to lie. Asbill relies on that framework; the panel quotes A.S. and an article recognizing that constitutionally compelled admission under rape-shield is “restricted” to bias/motive cases.
  • United States v. Pablo, 696 F.3d 1280 (10th Cir. 2012) – Provides the balancing of “exceedingly important values” in Rule 412: victim privacy and dignity versus a fair trial. The panel applies that balance to reject admission of an unsubstantiated third-party allegation.
  • United States v. Powell, 226 F.3d 1181 (10th Cir. 2000), and Richmond v. Embry, 122 F.3d 866 (10th Cir. 1997) – Supply the two constitutional gatekeeping prongs (relevance and materiality) for Confrontation Clause and complete-defense claims. The court applies both prongs, concluding the proffer was not relevant and risked jury confusion.
  • United States v. Begay, 937 F.2d 515 (10th Cir. 1991) – The panel distinguishes Begay, where prior abuse by another perpetrator was substantiated (guilty plea) and necessary to explain the victim’s physical injuries. By contrast, Asbill offered only an unsubstantiated allegation involving different conduct and no comparable explanatory need.
  • United States v. Bear Stops, 997 F.2d 451 (8th Cir. 1993) – Distinguished; Bear Stops involved uncontroverted prior abuse evidence used to explain a child’s behavior without risking a mini-trial. The Tenth Circuit notes later Eighth Circuit cases trend against admitting such evidence (e.g., Never Misses A Shot, 781 F.3d 1017 (8th Cir. 2015); Hawkghost, 903 F.3d 774 (8th Cir. 2018)).
• Confrontation/complete-defense framework:
  • Nevada v. Jackson, 569 U.S. 505 (2013) – The Constitution guarantees a meaningful opportunity to present a complete defense; limits grounded in standard evidentiary principles may be constitutional.
  • Delaware v. Fensterer, 474 U.S. 15 (1985), and Davis v. Alaska, 415 U.S. 308 (1974) – The jury must be permitted to assess credibility, but the right to cross-examine is not absolute.
  • Delaware v. Van Arsdall, 475 U.S. 673 (1986) – Trial courts have broad latitude to impose reasonable limits on cross-examination to avoid confusion, harassment, or marginally relevant forays.
• Impeachment mechanics and offers of proof:
  • United States v. Cerno, 529 F.3d 926 (10th Cir. 2008) – Contradiction as impeachment requires showing the witness’s testimony is not true; that presupposes an actual inconsistency.
  • Fed. R. Evid. 613(b) (2011 version) – Extrinsic evidence of a prior inconsistent statement is admissible only if the witness is given an opportunity to explain or deny it and the adverse party can examine the witness on it. The panel applies this strictly.
  • United States v. Flaming, 133 F.4th 1011 (10th Cir. 2025) – Reiterates the need to lay an “adequate foundation” showing that statements are in fact inconsistent.
  • United States v. McGirt, 71 F.4th 755 (10th Cir. 2023) – A prior affirmative assertion can be inconsistent with a present claim of lack of memory, but only where the lack of memory is about the event itself, not about prior testimony. The panel parses that difference to reject Asbill’s McGirt-based argument.
  • United States v. Adams, 271 F.3d 1236 (10th Cir. 2001) – On offers of proof: the preferred method is examination outside the jury’s presence; bare attorney avowal is “least favorable.” Defense’s failure to put the DHS document into the record or to examine the child outside the jury doomed the proffer.
  • United States v. McVeigh, 153 F.3d 1166 (10th Cir. 1998) – Warns against “mini-trials” and jury distraction from collateral factual disputes; undergirds the Rule 403-type concerns folded into the relevance analysis.

Legal Reasoning

1) Rule 412 and the constitutional-rights exception

Rule 412(a) generally bars evidence offered to prove a victim’s other sexual behavior or sexual predisposition. Rule 412(b)(1)(C) allows admission when exclusion would violate a criminal defendant’s constitutional rights. The Tenth Circuit applies a two-pronged constitutional screen—relevance and materiality—drawn from Powell and Richmond and embedded in Confrontation Clause and complete-defense doctrine.

Applying those prongs, the court held:

• No relevance: The DHS allegation was “unsubstantiated,” and the described conduct (“hands down her pants”) materially differed from the “graphic” hotel rape allegations. The proffered uses—motive to lie, alternative source of sexual knowledge, mental health explanation—were speculative or weakly tied to the charged conduct. Most importantly, admitting the evidence risked a distracting mini-trial about the brother’s alleged wrongdoing, a topic “tangentially related” to the issues being tried.
• Unsubstantiated ≠ false: The defense argued Rule 412 does not apply because “false prior claims” of sexual assault are not barred (citing the advisory committee note). The panel rejected equating “unsubstantiated” with “false,” grounding the difference in ordinary meaning. Without proof of falsity, the exception in the note did not help the defense.
• Rare success under 412(b)(1)(C): Echoing A.S., the court stresses that constitutional compulsion is uncommon and typically confined to proof of bias or motive to fabricate. The defense failed to connect the DHS allegation to a concrete theory of bias or fabrication in this case.

Because relevance failed, the court did not reach the materiality prong; the Rule 412 ruling stood without any constitutional violation.

2) Prior inconsistent statements (Rule 613(b) and related doctrines)

The defense sought to impeach T.C. with (a) a supposed denial of abuse in a DHS interview and (b) statements at a preliminary hearing that, in counsel’s view, contradicted her trial testimony about when and what happened at the hotel. The Tenth Circuit approved the trial court’s limits for two key reasons:

• DHS interview: The defense never introduced the DHS report into the record nor examined the witness outside the jury’s presence to create a clear proffer. Counsel’s uncertain avowal—he “believed” she denied “any sexual abuse” when asked—was inadequate. Without a specific, reliable proffer of the question asked and the answer given, the court could not determine whether a true inconsistency existed or whether Rule 412 and relevance concerns were overcome. Exclusion was a proper exercise of discretion.
• Preliminary hearing transcript:
  • No foundational inconsistency: The defense asked leading questions derived from a four-page excerpt concerning the day of checkout, but never first elicited trial testimony on the same point to establish an inconsistency. For instance, counsel asked whether T.C. had testified she slept 30 minutes—but never asked at trial how long she slept. Without a clash between trial testimony and prior statements, Rule 613(b) impeachment does not commence.
  • No “mutual exclusivity” between statements: T.C. testified at trial that the rape occurred on check-in day. The preliminary hearing excerpt described inappropriate touching on checkout day; those accounts are compatible (both could be true). The defense’s theory that T.C. spoke of only one incident at the preliminary hearing was not supported by the record excerpt.
  • McGirt inapplicable: The inconsistency that arises when a witness claims not to remember an event (at trial) after previously affirmatively describing it did not apply because T.C. said only that she did not remember her prior testimony, not that she lacked memory of the underlying events.

3) The “gun” line of questioning

The court clarified there was no exclusion of the fact the defendant gave T.C. a gun; that testimony reached the jury. The judge sustained a relevance objection only as to whether she had previously shot the gun. The defense’s speculative inference—that a rapist would not arm his victim—was too tenuous. No abuse of discretion occurred.

Impact and Practical Consequences

On Rule 412 litigation

• Raising prior abuse is harder when it is unsubstantiated and different in kind: Asbill signals that unsubstantiated third-party abuse allegations about a child victim rarely satisfy Rule 412(b)(1)(C), especially when the prior conduct differs materially from the charged acts. Defense teams should expect courts to weigh confusion and mini-trial risks heavily.
• “False allegations” require proof of falsity, not lack of substantiation: Practitioners cannot rely on the advisory note about “false prior claims” unless they can affirmatively demonstrate falsity. Mere “unsubstantiated” status does not open the door.
• Bias/motive to lie remains the best path: Following A.S., the only common constitutional route through Rule 412 is where the evidence supports a concrete theory of bias or motive to fabricate directly tied to the charged case. General claims about “alternative sources of sexual knowledge” are increasingly disfavored unless uniquely necessary to explain otherwise inexplicable medical or behavioral evidence.

On impeachment practice

• Foundational rigor is nonnegotiable: Before using extrinsic evidence to impeach, counsel must first elicit trial testimony on the same point. Only then can a transcript or report be used to prove an actual prior inconsistency.
• Offers of proof matter: To preserve issues and aid appellate review, examine the witness outside the jury’s presence or move the document into evidence for the limited purpose of the proffer. Bare avowals are the “least favorable” method and often insufficient (Adams).
• Memory-based impeachment has limits: McGirt allows treating a claimed lack of memory about an event as inconsistent with a prior affirmative statement about that event—not a lack of memory about prior testimony.
• Substantive use under Rule 801(d)(1)(A): If a prior statement under oath truly conflicts with trial testimony, it can come in substantively. But counsel must squarely raise that basis below and first establish the inconsistency.

System-level effects

• Stability for child-witness trials: The decision supports trial courts’ discretion to cabin collateral forays that risk confusing juries or retraumatizing child witnesses, while still permitting tailored questioning about opportunities to disclose.
• Inter-circuit dialogue: The Tenth Circuit’s approach narrows reliance on older Eighth Circuit cases like Bear Stops, aligning with more recent Eighth Circuit skepticism of “other-source” evidence absent compelling necessity.

Complex Concepts Simplified

• Rule 412 (Rape-Shield Rule): A rule that generally keeps out evidence about a victim’s other sexual behavior or sexual predisposition. It protects privacy and prevents unfair stereotyping. A narrow exception exists if excluding the evidence would violate the defendant’s constitutional rights—typically where it proves bias or motive to lie.
• Unsubstantiated vs. False: “Unsubstantiated” means the agency could not prove the allegation; it does not mean the allegation is false. Courts treat these differently. Only demonstrably false prior claims may be outside Rule 412’s bar.
• Confrontation Clause: The Sixth Amendment right to cross-examine adverse witnesses. It allows meaningful testing of credibility but does not guarantee boundless cross-examination. Judges can restrict to relevant, nonconfusing topics.
• Right to Present a Complete Defense: A due process-based right to present evidence. It yields to ordinary evidentiary limits on relevance, reliability, and prejudice.
• Prior Inconsistent Statement (Rule 613(b)): A classic impeachment tool. To use extrinsic proof (like a transcript), counsel must first show the witness gave different testimony at trial on the same point and offer the witness a chance to explain or deny the discrepancy.
• Offer of Proof: A method to show the judge (and preserve for appeal) what excluded evidence would have been. The best practice is to examine the witness outside the jury’s presence or mark and submit the document. Mere attorney summaries are disfavored.
• Mini-Trial Concern: Courts avoid side-litigation over collateral issues (e.g., proving whether a sibling committed abuse) that distract jurors from the main case.
• Standards of Review: Evidentiary calls are reviewed for abuse of discretion; constitutional exclusions are reviewed de novo. Both are deferential to trial management when the record is thin or speculative.

Key Takeaways

• Unsubstantiated allegations of third-party sexual abuse of a child victim are ordinarily irrelevant under Rule 412(b)(1)(C) absent a specific, compelling constitutional reason (e.g., concrete bias/motive to lie or necessary explanation for otherwise inexplicable medical/behavioral evidence).
• “Unsubstantiated” is not “false.” Without proof of falsity, the advisory note’s reference to false claims provides no safe harbor from Rule 412.
• To impeach with prior statements, establish the inconsistency first. Ask the trial question; only if the witness’s answer conflicts can you use the transcript or report.
• Preserve the record with proper offers of proof. Where Rule 412 or other sensitive exclusions are at issue, use in camera or outside-the-jury examinations and lodge the documents.
• Courts retain broad discretion to prevent cross-examination that risks confusion or devolves into collateral mini-trials, especially in child sexual abuse prosecutions.

Conclusion

United States v. Asbill reinforces two important constraints in sexual abuse trials: (1) the constitutional-rights exception to the rape-shield rule is narrow and rarely opens the door to unsubstantiated allegations of third-party abuse, particularly when the prior conduct is materially different and would distract the jury; and (2) impeachment by prior inconsistent statements is a structured process that demands precise foundational steps and clear record-making. The decision thus strengthens trial courts’ authority to focus juries on the central dispute, curbs collateral credibility battles, and sets a high bar for defendants seeking to introduce prior sexual history evidence of child complainants. While not binding precedent, Asbill will likely be cited for its careful articulation of Rule 412’s constitutional limits and its practical, stepwise insistence on proper impeachment foundations.