Plain-Error Limits on Unpreserved Daubert Challenges and Continued Foreclosure of Facial Second Amendment Attacks on 18 U.S.C. § 922(g)(1)

I. Introduction

In United States v. Tracy Grant, Jr. (4th Cir. July 13, 2026) (unpublished), the Fourth Circuit affirmed a federal felon-in-possession conviction under 18 U.S.C. §§ 922(g)(1) and 924(a)(8). After a January 2025 jury trial, Tracy Ranard Grant, Jr. was convicted of possessing a Glock Model 22 pistol and .40 caliber ammunition during an April 2023 investigation. Before trial, he stipulated that he had a prior felony conviction and knew of that status.

On appeal, Grant raised three issues: (1) alleged abandonment of the district court’s “gatekeeper” function under Federal Rule of Evidence 702 and Daubert v. Merrell Dow Pharmaceuticals Inc., 509 U.S. 579 (1993) by allowing a DNA expert (Barron) to testify; (2) insufficient evidence of possession, challenging the denial of a Rule 29 motion; and (3) a facial Second Amendment challenge to § 922(g)(1).

II. Summary of the Opinion

The court affirmed on all grounds. It held that admission of the DNA expert testimony was not erroneous under Rule 702 and Daubert, and emphasized that because Grant did not object at trial, review was for plain error. It also concluded the evidence was more than sufficient to sustain the jury’s possession finding, so denial of the Rule 29 motion was proper. Finally, it rejected the facial Second Amendment challenge as foreclosed by United States v. Canada, 123 F.4th 159 (4th Cir. 2024), which held that § 922(g)(1) is facially constitutional because it has a “plainly legitimate sweep.”

III. Analysis

A. Precedents Cited

  • Daubert v. Merrell Dow Pharmaceuticals Inc., 509 U.S. 579 (1993)
    The opinion invokes Daubert as the foundational authority for the trial judge’s gatekeeping role regarding expert testimony reliability. The Fourth Circuit’s disposition is pragmatic: even under the Daubert framework, the panel found the expert properly qualified and the testimony reliable, and—critically—review was constrained by the absence of a trial objection.
  • United States v. Garcia, 752 F.3d 382 (4th Cir. 2014)
    Cited for the standard that expert-admission rulings are ordinarily reviewed for abuse of discretion. The case frames the baseline review standard that is displaced here by plain-error review due to non-preservation.
  • United States v. Olano, 507 U.S. 725 (1993) and United States v. Walker, 32 F.4th 377 (4th Cir. 2022)
    These authorities supply the governing plain-error framework where evidentiary objections were not raised below. The panel uses them to justify heightened deference and to set the defendant’s burden on appeal.
  • United States v. Ojedokun, 16 F.4th 1091 (4th Cir. 2021) and United States v. Cohen, 888 F.3d 667 (4th Cir. 2018)
    Ojedokun is quoted for the three Olano prongs (error, plainness, substantial-rights effect). Cohen is cited for the discretionary fourth step—whether an appellate court should correct even a plain error—only when the error seriously affects fairness, integrity, or reputation of proceedings. Together, they underscore why unpreserved Daubert challenges rarely succeed on appeal.
  • United States v. Davis, 75 F.4th 428 (4th Cir. 2023)
    Central to the sufficiency analysis. The panel relies on Davis for de novo review of Rule 29 denials and for the “heavy burden” language: reversal is reserved for the “rare case where the prosecution’s failure is clear.” The court then concludes this case is not such a rarity.
  • United States v. Colon, 64 F.4th 589 (4th Cir. 2023) and United States v. Ancient Coin Collectors Guild, 899 F.3d 295 (4th Cir. 2018)
    These cases establish de novo review for constitutional questions, supplying the standard for the Second Amendment facial challenge (even though it is resolved by binding circuit precedent rather than extended constitutional analysis).
  • United States v. Brooks, 111 F.3d 365 (4th Cir. 1997)
    Used to support the alternative holding that even if admitting the DNA expert were error, it would be harmless under Rule 52 because other evidence independently supported guilt. This highlights an additional appellate barrier: showing not only error, but prejudicial effect.
  • United States v. Canada, 123 F.4th 159 (4th Cir. 2024)
    The controlling authority for the Second Amendment issue. The panel treats Canada as dispositive, reiterating its rule that § 922(g)(1) is facially constitutional because it has a “plainly legitimate sweep” and can be constitutionally applied in at least some circumstances.
  • United States v. Brewer, 157 F.4th 332 (4th Cir. 2025) and McMellon v. United States, 387 F.3d 329 (4th Cir. 2004) (en banc)
    Brewer is cited to commend counsel’s candor in conceding that Canada forecloses the facial challenge. McMellon grounds the court’s obligation to follow earlier published panel decisions unless overruled en banc or by the Supreme Court—explaining why the panel “is thus constrained” to reject Grant’s constitutional claim.

B. Legal Reasoning

  1. Expert testimony (Rule 702 / Daubert) under plain-error review
    The panel begins with a preservation-based pivot: because Grant did not object to the DNA expert’s testimony at trial, the court reviewed only for plain error. That matters because plain-error review is not simply “more deferential” in the abstract; it requires the defendant to prove an obvious error that affected substantial rights, and even then the court may decline to correct it absent serious harm to the judicial process. Applying that framework, the court held the government “sufficiently established” the expert’s qualifications and that the testimony was reliable under Rule 702 and Daubert. The panel also added an alternative rationale: any error would be harmless because other evidence supported guilt.
  2. Sufficiency of the evidence (Rule 29)
    Reviewing de novo, the panel relied on the “heavy burden” principle described in Davis and concluded the record contained “substantial evidence” that Grant possessed the firearm and ammunition. The court’s phrasing signals adherence to an appellate posture that respects the jury’s role: the question is not whether competing inferences exist, but whether the prosecution’s failure is clear. It was not.
  3. Facial Second Amendment challenge foreclosed by circuit precedent
    The panel’s reasoning is expressly hierarchical: regardless of the merits of a broad Second Amendment argument, Canada resolves the facial constitutionality of § 922(g)(1) within the Fourth Circuit. By invoking McMellon, the court underscores that panel fidelity to existing published precedent is mandatory absent en banc or Supreme Court intervention.

C. Impact

  • Trial preservation is decisive for Daubert disputes. The opinion reinforces that failing to object to expert testimony shifts appellate review to plain error, making reversal markedly less likely. Practically, it encourages defense counsel to litigate Rule 702 issues through timely objections and, where appropriate, pretrial motions and hearings.
  • Rule 29 challenges remain uphill. By quoting Davis and emphasizing the “rare case” standard, the court signals continued reluctance to disturb jury verdicts where the record contains substantial evidence.
  • Facial attacks on § 922(g)(1) remain closed in the Fourth Circuit. The court’s reliance on Canada indicates that defendants seeking Second Amendment relief must pursue (at most) as-applied theories or preserve issues for en banc/Supreme Court review; facial invalidation is foreclosed at the panel level.
  • Unpublished but instructive. Although the decision is “not binding precedent,” it is a clear signal of how panels will operationalize Canada, plain-error review, and harmless-error reasoning in routine felon-in-possession appeals.

IV. Complex Concepts Simplified

Rule 702 / Daubert “gatekeeping”
The trial judge must ensure expert testimony is offered by a qualified expert and is sufficiently reliable and relevant before the jury hears it.
Plain-error review
If a party fails to object in the trial court, the appellate court will usually reverse only for a clear/obvious error that likely affected the outcome, and even then only if leaving it uncorrected would seriously harm the fairness or integrity of the proceedings.
Harmless error
Even if a trial court made a mistake, the conviction can stand if the appellate court concludes the mistake did not matter to the verdict because other evidence was enough.
Rule 29 motion for judgment of acquittal
A defendant’s request for the judge to set aside the case (or the verdict) because the evidence is legally insufficient to support conviction.
Facial constitutional challenge; “plainly legitimate sweep”
A facial challenge argues a law is unconstitutional in all (or nearly all) applications. Under Canada, § 922(g)(1) survives a facial challenge because there are at least some circumstances where applying it is constitutional—i.e., it has a legitimate range of valid applications (a “sweep”).
Stipulation
An agreement between the parties on a fact (here, felony status and knowledge of it) so the jury need not hear evidence to prove that fact.

V. Conclusion

United States v. Grant is a straightforward affirmance with three practical lessons: (1) unpreserved expert-testimony objections are reviewed under the demanding plain-error standard and may also be defeated by harmless-error analysis; (2) sufficiency challenges under Rule 29 remain difficult to win absent a clear failure of proof; and (3) within the Fourth Circuit, United States v. Canada continues to foreclose facial Second Amendment challenges to 18 U.S.C. § 922(g)(1), with panel courts bound by circuit precedent unless overruled en banc or by the Supreme Court.