Okla. Stat. tit. 21, § 645 Is Not a Categorical “Crime of Violence” or ACCA “Violent Felony” Because It Reaches Unborn Victims

I. Introduction

In United States v. Singer (10th Cir. Jan. 23, 2026), the Tenth Circuit addressed whether two Oklahoma convictions for assault and battery with a dangerous weapon under Okla. Stat. tit. 21, § 645 qualify (1) as “crimes of violence” under the United States Sentencing Guidelines (“Guidelines”) and (2) as “violent felonies” under the Armed Career Criminal Act (“ACCA”), 18 U.S.C. § 924(e).

The defendant, Christopher A. Singer, pleaded guilty to federal ammunition possession after a felony conviction. At sentencing, the presentence investigation report treated Singer’s two § 645 convictions (along with a robbery with a firearm conviction) as predicates that increased his Guidelines range and triggered the ACCA’s 15-year mandatory minimum. Singer objected, arguing that § 645 reaches assaults on unborn victims and therefore sweeps more broadly than the federal “person of another” element in both the Guidelines and ACCA.

The core issue became a state-law scope question: does Oklahoma’s § 645 allow conviction when the victim is unborn? Because Oklahoma courts had not directly answered that question for § 645, the Tenth Circuit made an Erie-style prediction of how the Oklahoma Court of Criminal Appeals would rule.

II. Summary of the Opinion

The Tenth Circuit reversed and remanded for resentencing. It held that, under its best prediction of Oklahoma law, § 645 criminalizes assault and battery with a dangerous weapon against an unborn person. Under binding federal precedent, crimes that can be committed against unborn victims are not categorical matches for the Guidelines’ and ACCA’s force clauses because those clauses require force against “the person of another,” which the Tenth Circuit has interpreted to mean persons “born alive.”

As a result, Singer’s § 645 convictions could not be counted as categorical “crimes of violence” (Guidelines) or “violent felonies” (ACCA). The district court therefore erred by applying the enhanced sentencing provisions.

III. Analysis

A. Precedents Cited

1. The federal categorical-approach framework

  • United States v. O'Connor, 874 F.3d 1147 (10th Cir. 2017): Cited for the categorical approach’s central instruction—compare statutory elements, not underlying facts. Singer applies O’Connor to frame the analysis as purely element-to-definition matching.
  • Mathis v. United States, 579 U.S. 500 (2016): Cited for the ACCA categorical approach and the requirement to ignore the facts and focus on elements. Singer relies on Mathis to confirm that the ACCA analysis mirrors the Guidelines analysis here.
  • United States v. Cartwright, 678 F.3d 907 (10th Cir. 2012) and United States v. Wray, 776 F.3d 1182 (10th Cir. 2015): Cited for the standard of review—de novo review of whether a conviction is a crime of violence/violent felony.

2. The “unborn victim” mismatch rule (binding circuit precedent)

  • United States v. Adams, 40 F.4th 1162 (10th Cir. 2022): The controlling precedent. Adams held that “crime of violence” in U.S.S.G. § 4B1.2(a)(1) does not include crimes against unborn victims because “the person of another” means only those “born alive” (via the Dictionary Act, 1 U.S.C. § 8(a)). Singer extends Adams to Oklahoma § 645: if § 645 permits conviction when the victim is a fetus, there is a categorical mismatch and the statute cannot qualify under the force clause.

3. Prior Tenth Circuit treatment of § 645 and why it did not control

  • United States v. Taylor, 843 F.3d 1215 (10th Cir. 2016): The district court believed Taylor compelled treating § 645 as categorically a Guidelines crime of violence. Singer distinguishes Taylor on a key ground: Taylor did not address whether § 645 reaches unborn victims. Because the “unborn victim” overbreadth theory was not squarely presented or decided, Taylor did not resolve the issue Singer raised.

4. State-law interpretive anchors for the Erie prediction

  • Erie R.R. Co. v. Tompkins, 304 U.S. 64 (1938): Quoted for the proposition that state law is ultimately determined by the state—federal courts must follow state courts’ authoritative voice.
  • Valley Forge Ins. v. Health Care Mgmt. Partners, Ltd., 616 F.3d 1086 (10th Cir. 2010): Cited for the method: consult state decisions, or predict how the state high court would rule.
  • Hughes v. State, 868 P.2d 730 (Okla. Crim. App. 1994): A foundational Oklahoma decision. Hughes held that under Oklahoma’s homicide statute then in effect, a viable fetus is a “human being” (thus capable of being a crime victim), and it overruled a prior decision that had excluded a viable fetus from “person” status in the context of assault and battery with a deadly weapon. Singer treats Hughes as strong evidence of the Oklahoma Court of Criminal Appeals’ willingness to interpret victim terms broadly to include viable fetuses absent clear statutory exclusion.
  • State v. Green, 474 P.3d 886 (Okla. Crim. App. 2020): Green extended similar reasoning to the child neglect statute, concluding that “child” includes a viable fetus. Critically, Green stated that “just as a viable fetus may be the victim of a homicide or an assault with a dangerous weapon, so too may he or she be a victim of child neglect,” language Singer reads as strongly suggestive of inclusion of unborn victims across person-protecting statutes.
  • Pino v. United States, 507 F.3d 1233 (10th Cir. 2007): Used for the “reasonably clear and principled course” standard in making an Erie prediction where state law is unsettled.
  • Pehle v. Farm Bureau Life Ins., 397 F.3d 897 (10th Cir. 2005), Cottonwood Mall Shopping Ctr., Inc. v. Utah Power & Light Co., 440 F.2d 36 (10th Cir. 1971), and Stuart v. Colo. Interstate Gas Co., 271 F.3d 1221 (10th Cir. 2001): Cited for Erie-prediction methodology and the goal of reaching the result that would probably be reached in state court, including use of “all resources available.”

5. Legislative silence and interpretive caution

  • Cent. Bank of Denver, N.A. v. First Interstate Bank of Denver, N.A., 511 U.S. 164 (1994) and Encino Motorcars, LLC v. Navarro, 584 U.S. 79 (2018): Invoked to underscore the limited inferential value of legislative silence. Singer uses these cases to discount Oklahoma’s failure to amend § 645 as a reliable indicator of intent to exclude unborn victims.

6. The concurrence’s “certainty” principle for ACCA predicates

  • United States v. Degeare, 884 F.3d 1241 (10th Cir. 2018): Judge Matheson concurred in the judgment, emphasizing ACCA’s demand for certainty—if state-law scope is uncertain, the conviction cannot serve as an ACCA predicate. This concurrence reinforces a defense-favorable consequence of ambiguity in state offense scope in the ACCA context.

B. Legal Reasoning

1. Step one: define the federal comparator

Both the Guidelines force clause (U.S.S.G. § 4B1.2(a)(1)) and the ACCA force clause (18 U.S.C. § 924(e)(2)(B)(i)) require the use/attempted use/threatened use of physical force against “the person of another.” Singer treats the phrases as “identical in the only way relevant here,” so Adams’s interpretation controls both regimes.

Under United States v. Adams, “the person of another” is limited to those “born alive.” Therefore, if a state statute permits conviction with an unborn victim, it is categorically broader than the federal definition and cannot qualify.

2. Step two: determine the elements’ reach under Oklahoma law (the dispositive question)

The opinion recognizes the novelty: Oklahoma’s Constitution, statutes, and courts had not “squarely addressed” whether § 645 applies to unborn victims. The panel therefore makes an Erie prediction, leaning heavily on Hughes v. State and State v. Green.

The court’s reasoning is essentially analogical and methodological:

  • Pattern recognition in Oklahoma precedent: Twice, the Oklahoma Court of Criminal Appeals addressed whether an unborn person may be a crime victim where the statute protects a “human being”/“child”/“person,” and twice it answered yes (for viable fetuses).
  • Preference for judicial reasoning over legislative silence: The government argued that Oklahoma’s post-Hughes amendments to Okla. Stat. tit. 21, §§ 652 and 691—expressly referencing “an unborn child”—imply exclusion from § 645, which was not similarly amended. The panel rejected that inference as less persuasive than near-on-point case law and as resting on uncertain assumptions about legislative inaction.
  • Handling Green’s caveat: Green cautioned that terms like “person” and “human being” have no universal meaning across Oklahoma statutes. The panel acknowledged this, but concluded that Hughes/Green still provide the best predictor of how the Oklahoma Court of Criminal Appeals would treat § 645 when asked directly.
  • Uniform Jury Instructions argument discounted: The government pointed to Oklahoma Uniform Jury Instructions that expressly include “unborn child” for §§ 652 and 691 but not for § 645. The panel reasoned that the probative value mirrors (and does not exceed) the statutory silence, and noted that in Green, the child neglect statute lacked express “unborn child” language yet still reached viable fetuses.

3. Step three: apply the categorical mismatch and reverse

Having predicted that § 645 reaches unborn victims, Singer applies Adams’s categorical mismatch rule: because § 645 “allows a conviction” when the victim is a fetus, it does not categorically match the force clause. The consequence is twofold:

  • The § 645 convictions are not “crimes of violence” under the Guidelines, affecting the base offense level and related calculations.
  • The § 645 convictions are not “violent felonies” under the ACCA, eliminating them as ACCA predicates and undermining application of the 15-year mandatory minimum.

C. Impact

1. Immediate sentencing consequences in the Tenth Circuit

Singer is significant because it removes a commonly charged Oklahoma violent-assault conviction—Okla. Stat. tit. 21, § 645—from the categorical “crime of violence” / “violent felony” boxes, at least where the analysis is confined to the force clause and where Adams’s “born alive” limitation governs.

Practically, this may:

  • reduce Guidelines ranges in firearm and career-offender-adjacent contexts where § 645 was used as a crime-of-violence predicate;
  • prevent or undo ACCA enhancements where § 645 supplied one or more of the three required predicates;
  • increase litigation around other Oklahoma person-protecting statutes and whether they reach unborn victims (and thus fall outside the force clause).

2. Recalibrating reliance on earlier circuit decisions like Taylor

Although United States v. Taylor previously treated § 645 as categorically violent for Guidelines purposes, Singer shows that Taylor’s holding does not foreclose later overbreadth arguments not addressed there. In other words, categorical “status” can be destabilized by a newly recognized breadth problem (here, victim-status breadth), especially after intervening interpretive precedent like United States v. Adams.

3. Broader doctrinal implications: “personhood” as an elements-level overbreadth issue

Singer highlights an underappreciated categorical-approach axis: the identity of who can be a victim, not only what level of force is used. After Adams, statutes that extend person-protection to unborn victims can become categorically disqualified—even if the conduct is otherwise plainly violent.

4. Federalism and Erie prediction in criminal sentencing

The decision also underscores how federal sentencing can turn on predictive state-law analysis. When a state’s highest criminal court has not squarely spoken, federal courts must decide whether to extrapolate from adjacent state decisions. Singer adopts a methodology that privileges the state court’s reasoning trajectory over legislative silence, a choice that may influence future Erie-style predictions in federal sentencing appeals.

IV. Complex Concepts Simplified

  • Categorical approach: A method that asks what a statute’s elements allow a conviction for, not what the defendant actually did. If the statute covers any conduct outside the federal definition, it fails categorically.
  • “Crime of violence” (Guidelines) / “violent felony” (ACCA): Labels that trigger higher sentencing ranges or mandatory minimums. Here, both require force against “the person of another.”
  • “Person of another” and the “born alive” rule: Under United States v. Adams, the federal phrase excludes unborn victims. So a state statute that includes unborn victims is broader than the federal definition.
  • Erie prediction: When state law is unsettled, a federal court predicts how the state’s highest court would resolve the issue, using state decisions and other reliable indicators.
  • Legislative silence: When the legislature does not amend a statute, courts are cautious about inferring intent from that inaction because multiple explanations are possible.

V. Conclusion

United States v. Singer establishes a clear sentencing rule in the Tenth Circuit: where Oklahoma’s Okla. Stat. tit. 21, § 645 is predicted to reach assaults on unborn victims, it is not categorically a “crime of violence” under the Guidelines or a “violent felony” under the ACCA because, under United States v. Adams, the federal force clauses protect only persons “born alive.” The decision narrows the pool of Oklahoma predicates available for federal enhancements and demonstrates how victim-status breadth, proven (or predicted) under state law, can be outcome-determinative under the categorical approach.