Tenth Circuit Rejects Categorical Approach to Rule 413 and Reaffirms that Prior Prostitution Is Not Probative of Consent

Comprehensive Commentary on United States v. Clay (10th Cir. 2025)

Introduction

In United States v. Clay, the Tenth Circuit affirmed the convictions of a defendant for kidnapping and transporting an individual across state lines for illicit sexual activity arising from a violent assault that began in El Paso, Texas, and continued at the defendant’s New Mexico residence. The prosecution also introduced testimony from the defendant’s adopted daughter under Federal Rule of Evidence 413 to show prior sexual assault. On appeal, the defendant challenged three core rulings: (1) exclusion of the victim’s prior prostitution to prove consent, (2) admission of the adopted daughter’s testimony under Rule 413 and Rule 403, and (3) limits on cross-examination of the adopted daughter.

The Court’s decision is notable for two reasons. First, it squarely clarifies within the Tenth Circuit that Rule 413’s threshold—whether “the defendant is accused of a sexual assault”—is assessed through a circumstance-specific, conduct-focused lens, not through a “categorical” elements-based approach. Second, it reaffirms that evidence of a complainant’s prior prostitution does not meaningfully bear on consent to later sexual acts and is not constitutionally compelled under Rule 412’s exception. The opinion also underscores the consequences of inadequate appellate briefing, resulting in waivers on several cross-examination claims.

Summary of the Judgment

• Rule 412 and Constitutional Claims: The district court properly excluded evidence of the victim’s prior prostitution offered to prove she consented to sexual acts with the defendant. Under Tenth Circuit precedent, such evidence is not relevant to consent for the later encounter and thus is not constitutionally required for admission under Rule 412(b)(1)(C).
• Rule 413 Applicability: The Court rejected the defendant’s argument that Rule 413 applies only when the charged crime’s statutory elements include sexual assault. Instead, Rule 413 applies whenever the conduct underlying the current charges “involves” sexual assault within the rule’s definition (a conduct-based, circumstance-specific inquiry). This reading aligns with prior Tenth Circuit authority and with the Seventh and Eighth Circuits.
• Rule 403 Balancing: The district court did not abuse its discretion in admitting the adopted daughter’s testimony. Applying the specialized Enjady factors, the court reasonably found high probative value and mitigated prejudice through limiting instructions.
• Waiver by Inadequate Briefing: The defendant’s arguments about limits on cross-examining the adopted daughter—concerning her mental health, prior allegations, financial matters, and prior inconsistent statements—were deemed waived for inadequate presentation in the opening brief.
• Result: Convictions affirmed.

Analysis

Key Precedents and Authorities Cited

• Rule 412 and Constitutional Interaction
  • United States v. Palms (10th Cir. 2021): Prior prostitution does not meaningfully bear on whether the victim was later forced or coerced; not probative of consent to later acts. The Court relied on Palms to reject the consent-by-prostitution theory.
  • United States v. Powell (10th Cir. 2000): Exclusion of sexual behavior evidence that is only “marginally relevant” does not violate due process or confrontation rights.
  • United States v. A.S. (10th Cir. 2019): Constitutional admission of sexual history is typically confined to bias/motive theories; the appellant’s undeveloped bias argument was waived here.
  • Delaware v. Van Arsdall (U.S. 1986), Fero v. Kerby (10th Cir. 1994): General confrontation and due process principles—effective cross-examination is guaranteed but subject to reasonable limits.
• Rule 413: “Accused of a Sexual Assault” and the Conduct-Based Approach
  • United States v. Batton (10th Cir. 2010): The Court previously focused on the defendant’s conduct—not the elements of the charged offense—to determine Rule 413 applicability.
  • United States v. Foley (7th Cir. 2014): Rule 413 focuses on conduct; “how the charges have been drafted” is not determinative.
  • United States v. Ahmed (8th Cir. 2024); United States v. Blazek (8th Cir. 2005): Kidnapping and other offenses fall within Rule 413 when the conduct involved sexual assault.
  • United States v. Courtright (7th Cir. 2011): “Accused” refers to what is charged in the case, but whether those charges “involve” sexual assault requires examining the conduct.
  • United States v. Martinez-Hernandez (10th Cir. 2005), United States v. Escalante (5th Cir. 2019): “Involving conduct” language flags a circumstance-specific inquiry.
  • Nijhawan v. Holder (U.S. 2009), United States v. White (10th Cir. 2015), United States v. Leaverton (10th Cir. 2018): Textual cues guide whether a statute or rule demands a categorical (elements-based) or conduct-based analysis.
  • Daubert v. Merrell Dow (U.S. 1993): Federal Rules of Evidence are interpreted like statutes—relevant to the Court’s textual analysis of Rule 413.
  • Wright & Miller treatise § 5384: Advocates an elements-based reading of “involving,” which the Tenth Circuit declined to adopt, emphasizing Rule 403 as the backstop for odd cases.
• Rule 403 and Enjady Balancing for Rule 413 Evidence
  • United States v. Enjady (10th Cir. 1998): Specialized multi-factor test for weighing probative value vs. prejudice in sexual-assault propensity evidence.
  • United States v. Benally (10th Cir. 2007): Preliminary preponderance finding; limiting instructions mitigate prejudice.
  • United States v. Perrault (10th Cir. 2021): Limiting instructions can sufficiently cabin improper propensity inferences.
  • United States v. Mercer (10th Cir. 2016) (unpublished): Time-lapse considerations and their flexibility in Rule 413 contexts.
• Standards of Review and Waiver
  • United States v. Martinez (10th Cir. 2024), United States v. Burgess (10th Cir. 2024), United States v. Silva (10th Cir. 2018): De novo for legal interpretation; abuse of discretion for evidentiary rulings; reversible only if beyond “bounds of permissible choice.”
  • United States v. Cooper (10th Cir. 2011), United States v. Leffler (10th Cir. 2019), Bronson v. Swensen (10th Cir. 2007), United States v. Wooten (10th Cir. 2004), United States v. Kunzman (10th Cir. 1995), United States v. McClatchey (10th Cir. 2000), Meek v. Martin (10th Cir. 2023): Waiver by inadequate briefing; need to identify arguments, record citations, and authorities in the opening brief.

Legal Reasoning and How the Court Reached Its Decision

The Court addressed three major issues.

1) Rule 412 and the Constitution: Prior Prostitution Is Not Consent Evidence

• Rule 412 bars evidence of a victim’s other sexual behavior or predisposition unless a narrow exception applies. The constitutional exception in criminal cases (Rule 412(b)(1)(C)) admits such evidence only when exclusion would violate due process or confrontation rights.
• Relying on Palms, the Court reasoned that prior prostitution is not probative of consent to sexual acts on a different occasion. The “once-a-prostitute-always-consenting” line of reasoning is impermissible stereotyping, not constitutionally significant probative value.
• The defense’s underdeveloped argument that prior prostitution showed bias or motive to lie was deemed waived. The record did not present a concrete, non-stereotyped theory of bias that would compel admission.
• Rule 412(b)(1)(B), which admits specific prior sexual conduct with the defendant to prove consent, was inapplicable; the proffer concerned the complainant’s prior acts with others.

2) Rule 413’s Threshold Is Conduct-Based, Not Elements-Based

• Text and Precedent: The Court read Rule 413’s definition of “sexual assault” as turning on whether the case “involves” specified sexual conduct, not whether “sexual assault” is an element of the charged offense. That reading “directs our attention not to the terms of [a] statute but to [ ] underlying conduct.”
• Batton foreclosed a categorical approach: Rule 413 applied there even though the charge was transporting a minor to engage in illicit sexual activity; the rule turned on what the defendant actually did, not on the statutory elements.
• Alignment with Other Circuits: The Seventh and Eighth Circuits have likewise focused on conduct, not elements (e.g., Foley, Ahmed).
• Addressing Counterarguments: While a leading treatise reads “involving” as elements-based (to avoid odd hypotheticals), the Court emphasized that Rule 403 exists to screen out idiosyncratic or unfair applications without distorting Rule 413’s text.
• Application to Clay: Even though Clay’s charges included kidnapping and transport for illicit sexual activity, the underlying conduct—violent nonconsensual sexual penetration—fell squarely within Rule 413(d). Thus, Rule 413 permitted the adopted daughter’s testimony as prior sexual assault evidence.

3) Rule 403 and Enjady: No Abuse of Discretion in Admitting the Rule 413 Testimony

• Preponderance Finding: The district court first found a jury could reasonably find by a preponderance that the prior assaults occurred, based on the adopted daughter’s testimony (no corroboration required).
• Enjady Factors—Probative Value:
  • Similarity: Strong parallels—nonconsensual vaginal, anal, and oral penetration; use of lubricant; repeated “good girl” language. Differences (e.g., the family relationship vs. stranger kidnapping) did not defeat probative value.
  • Temporal Proximity: While some assaults were years earlier, one was only months before the charged offense, sustaining probative value.
  • Frequency and Need: Multiple incidents; the case featured a consent defense, making intent and pattern evidence highly probative.
  • Alternatives: Even if other evidence existed, the specialized probative value of prior sexual assault evidence remained significant.
• Enjady Factors—Prejudice and Safeguards:
  • Prejudice: Not unfair merely because it suggests propensity—Rule 413 expressly allows that inference. Risk moderated by limiting instructions.
  • Distraction/Time: The testimony did not unduly distract from the central issues or consume excessive time.
  • Limiting Instruction: The court told jurors the defendant was not on trial for uncharged acts; such instructions are a well-established way to mitigate prejudice.

Impact and Implications

This decision has important downstream effects on federal practice in the Tenth Circuit:

• Rule 413 Is Now Firmly Conduct-Based in the Tenth Circuit: Prosecutors may invoke Rule 413 in cases where the indictment does not list a “sex offense” per se (e.g., kidnapping, interstate transport, certain assaults), so long as the conduct underlying those charges involved acts that fit Rule 413(d). This will likely increase the availability of prior sexual assault evidence in mixed-offense prosecutions.
• Rule 403 as the Guardrail: Defense counsel should be prepared for robust Enjady balancing rather than winning at the Rule 413 “gate.” Similarity, recency, frequency, and the availability of less prejudicial means will be the battleground for exclusion.
• Rape Shield Reaffirmed: Attempts to introduce a complainant’s prior prostitution as consent evidence remain untenable. However, carefully developed bias/motive theories—properly articulated and supported—could open a narrow constitutional path under Rule 412(b)(1)(C). Clay’s briefing shows the danger of underdeveloped constitutional arguments.
• Appellate Practice: The opinion is an emphatic warning: failure to fully brief issues—with record citations and relevant authority—in the opening brief risks waiver. Raising specifics for the first time in the reply will not cure the defect.
• Trial Management: Trial courts are encouraged to use limiting instructions to contain prejudice when admitting Rule 413 evidence. Expect renewed emphasis on precise, case-tailored instructions.
• Potential Expansion to Other Contexts: The conduct-based view could reach beyond kidnapping/transport cases. For example, a robbery during which a sexual assault occurs might qualify as a Rule 413 case, subject to Rule 403 screening and limiting instructions.

Complex Concepts Simplified

• Rule 412 (Rape Shield): Generally blocks evidence of a victim’s other sexual behavior or predisposition. Two key criminal-case exceptions:
  • 412(b)(1)(B): Specific prior sexual acts between the victim and the defendant to prove consent.
  • 412(b)(1)(C): Constitutionally required evidence (e.g., specific, non-stereotyped bias/motive to fabricate). Prior prostitution with others rarely fits this, absent a developed bias theory.
• Confrontation and Due Process: They protect the right to present a defense and cross-examine witnesses, but judges may limit questioning that is harassing, confusing, minimally relevant, or contrary to evidentiary rules like Rule 412.
• Rule 413 (Propensity Evidence for Sexual Assault): Allows evidence of other sexual assaults in sexual-assault cases to show propensity. The threshold question—whether the defendant is “accused of a sexual assault”—looks to the conduct underlying the charges, not merely to the elements of the statutes charged.
• Categorical vs. Circumstance-Specific Approach:
  • Categorical (elements-based): Compares statutory elements, ignoring case-specific facts.
  • Circumstance-specific (conduct-based): Focuses on what actually happened in the case. The Tenth Circuit adopts this for Rule 413’s threshold question.
• Rule 403 and Enjady Balancing: Even if Rule 413 applies, courts must weigh probative value against unfair prejudice. Enjady’s tailored factors focus on proof strength, similarity, timing, frequency, alternative evidence, risk of improper verdicts, distraction, and time consumption. Limiting instructions play a central role.
• Waiver on Appeal: Arguments must be fully developed in the opening brief with authority and record citations. New arguments in the reply are typically too late.

Practice Takeaways

• For Prosecutors:
  • When the conduct underlying non-sex-offense charges involved sexual assault, consider Rule 413 to admit prior sexual assaults. Be ready with a strong Enjady showing and propose targeted limiting instructions.
  • Anticipate defense arguments about remoteness or dissimilarity; marshal specific similarities, including distinctive verbal or behavioral patterns.
• For Defense Counsel:
  • Front-load Rule 403 arguments with granular analysis: dissimilarities, time gaps, intervening events, the sufficiency of alternative proof, and the risk of unfair emotional impact.
  • On Rule 412 issues, avoid generic “consent-by-prostitution” theories. If bias or motive is the aim, articulate a concrete and non-stereotyped theory with supporting proffers.
  • On appeal, meticulously brief each evidentiary complaint in the opening brief with record citations and relevant authorities to avoid waiver.
• For Trial Courts:
  • Expect more Rule 413 proffers in mixed-offense cases; apply a conduct-based threshold and rigorous Enjady balancing.
  • Use precise limiting instructions to cabin the jury’s use of propensity evidence and emphasize that the defendant is being tried only for charged crimes.

Conclusion

United States v. Clay delivers two important clarifications in Tenth Circuit law. First, the Court emphatically reaffirms that a complainant’s prior prostitution is not probative of consent to a later sexual encounter, and its exclusion does not violate the Constitution absent a specific, well-supported bias or motive theory. Second, the Court cements a conduct-based, circumstance-specific approach to Federal Rule of Evidence 413’s threshold: a defendant is “accused of a sexual assault” when the charged conduct, as alleged and proved, involves sexual assault as defined in Rule 413(d), regardless of whether the statutory elements of the charge expressly include sexual assault. Rule 403 remains the primary backstop for excluding unduly prejudicial applications.

Practically, Clay is poised to influence how prosecutors charge and try cases with intertwined sexual and non-sexual offenses, how defense counsel structure pretrial evidentiary challenges and appellate briefs, and how trial courts calibrate limiting instructions and apply Enjady. The decision harmonizes Tenth Circuit law with other federal circuits, clarifies doctrinal uncertainty around Rule 413’s scope, and underscores the enduring power of Rule 412 to prevent stereotyping and protect fair-trial values.