United States v. Halbert: Clarifying the Evidentiary Burden for Sentencing-Disparity Challenges on Appeal

1. Introduction

United States v. Halbert, No. 24-6181 (10th Cir. July 21, 2025) concerns the propriety of an 18-year sentence imposed on Natalie Dawn Halbert for two counts of child sex trafficking. Halbert appealed, contending her sentence was substantively unreasonable because (1) her traumatic history, intellectual limitations, and addiction justified a lower sentence and (2) the district court failed to alleviate purported nationwide sentencing disparities. The Tenth Circuit, per Judge Moritz, affirmed in a non-precedential order and judgment, but the panel’s reasoning articulates—persuasively although not binding—a clear rule: an appellate court will not find an abuse of discretion for an unwarranted disparity where the defendant failed to supply the statistical or comparative evidence to the sentencing court.

2. Summary of the Judgment

Guidelines Calculation: Offense-level 43 produced a life-imprisonment range; Halbert had only one criminal-history point.
Departures & Variances: District court granted (a) a downward departure under U.S.S.G. § 5K1.1 for substantial assistance and (b) a downward variance based on mental health, addiction, and atypical culpability, ultimately imposing 18 years (216 months) on each count, concurrent.
Standard of Review: Substantive reasonableness reviewed under abuse-of-discretion; below-Guidelines sentences receive a presumption of reasonableness (United States v. Carter).
Holding: The 18-year sentence was not “arbitrary, capricious, whimsical, or manifestly unreasonable” (Munoz-Nava standard). The district court adequately weighed mitigating factors, and no unfair disparity was shown because Halbert failed to present statistical evidence below.

3. Analysis

3.1 Precedents Cited

The panel’s discussion draws on a line of Tenth Circuit authority governing substantive reasonableness review:

United States v. Conlan, 500 F.3d 1167 (10th Cir. 2007) – identifies the difference between procedural and substantive review.
United States v. Alapizco-Valenzuela, 546 F.3d 1208 (10th Cir. 2008) – reiterates the § 3553(a) framework.
United States v. Munoz-Nava, 524 F.3d 1137 (10th Cir. 2008) – sets out the “arbitrary, capricious, whimsical, or manifestly unreasonable” abuse-of-discretion test.
United States v. Carter, 941 F.3d 954 (10th Cir. 2019) – explains the presumption of reasonableness for below-Guidelines sentences.
United States v. Byrne, 171 F.3d 1231 (10th Cir. 1999) – original articulation of the whimsical/unreasonable standard.
Verlo v. Martinez, 820 F.3d 1113 (10th Cir. 2016) – clarifies that a court cannot err by ignoring evidence never presented.

Cumulatively, these cases underpin two doctrinal pillars: (1) deference to district-court sentencing discretion, and (2) a litigant’s duty to create a record that supports any disparity argument.

3.2 Legal Reasoning

Presumption of Reasonableness. Because the 18-year sentence sat far below the life-sentence guideline, the panel began with a strong presumption that the sentence was reasonable (Carter).
Mitigating Factors Already Accounted For. The district court explicitly credited Halbert’s intellectual disability, addiction, and poverty— mitigating factors Halbert re-raised on appeal. Since these factors produced a substantial downward variance, the appellate court saw no abuse.
Sentencing-Disparity Challenge. Halbert cited national statistics for child-sex-trafficking sentences only on appeal. Under Verlo, the appellate court refuses to penalize the district court for failing to consider non-existent record material. This reasoning crystallizes a clear evidentiary rule: a defendant must introduce disparity evidence at the sentencing hearing; raising it for the first time on appeal is ineffectual.
Ultimate Balancing of § 3553(a) Factors. The court found that the 18-year term simultaneously: (a) acknowledged Halbert’s reduced culpability, yet (b) expressed the seriousness of child sex trafficking and the need to protect the public. The balancing fell well within the permissible range of discretion.

3.3 Likely Impact of the Decision

Litigation Practice: Defense counsel must now be especially diligent in presenting comparative sentencing statistics at the district-court level if they intend to raise § 3553(a)(6) disparity arguments later.
Appellate Strategy: The decision signals that failure to develop the record below forecloses substantive appellate review, effectively raising the bar for overturning below-Guidelines sentences.
Substantive Law: While the order is not precedential, its persuasive reasoning strengthens existing doctrine that below-Guidelines sentences are insulated from appellate reversal absent egregious misapplication.

4. Complex Concepts Simplified

Offense Level 43: The highest level in the Sentencing Guidelines; regardless of criminal-history category, it yields a recommended sentence of life imprisonment.
Downward Departure vs. Downward Variance: A departure is an adjustment inside the Guideline framework (e.g., § 5K1.1 for substantial assistance), whereas a variance is a court-imposed deviation outside the Guidelines based on § 3553(a) factors.
Substantive Reasonableness: Focuses on the length of the sentence in light of statutory factors, distinct from procedural correctness.
§ 3553(a)(6) Disparity Factor: Requires courts to avoid unjustified sentence differences among similarly situated defendants nationwide.
Presumption of Reasonableness: In the Tenth Circuit, any below-Guidelines sentence is presumed reasonable; the defendant must rebut this with compelling evidence.

5. Conclusion

United States v. Halbert reinforces the deferential standard governing appellate review of sentencing and clarifies the defendant’s burden when alleging unwarranted disparities. If disparity data are not presented to the district court, the argument all but evaporates on appeal. While the order is formally non-precedential, its cogent logic will likely guide litigants and judges alike, underscoring that sentencing advocacy must be evidence-driven and contemporaneous. Practitioners should treat Halbert as a cautionary tale: build the record first, appeal second.