Pharmacist–Prescriber Communications as Lay Testimony and “Isolated, Inadvertent” Addiction References: Seventh Circuit Guardrails in § 841(a) Prescriber Prosecutions

United States v. Barnett K. Fung, No. 25-1605 (7th Cir. July 24, 2026)

I. Introduction

In United States v. Barnett K. Fung, the Seventh Circuit affirmed the conviction and sentence of Dr. Barnett K. Fung, an Illinois-licensed podiatrist with DEA prescribing authority, for one count of unlawfully dispensing a controlled substance in violation of 21 U.S.C. § 841(a). The government charged Dr. Fung in a superseding indictment with 74 counts—each tied to an opioid prescription it alleged was issued outside the usual course of professional practice and without a legitimate medical purpose. A jury acquitted on 73 counts but convicted on Count Seven, based on a hydrocodone (Norco) prescription issued to undercover DEA Special Agent Emilia Fernandez (posing as “Emilia Figueroa”).

The appeal presented four practical issues frequently litigated in “pill mill” and prescriber-liability cases: (1) the boundary between lay and expert testimony under Federal Rules of Evidence 701 and 702, especially when the witness is a trained professional (here, a pharmacist); (2) when a trial incident warrants a mistrial; (3) what counts as sufficient evidence of a prescriber’s subjective knowledge under Ruan; and (4) how thoroughly a district court must explain a criminal fine under U.S.S.G. § 5E1.2.

II. Summary of the Opinion

The Seventh Circuit (Pryor, J.) affirmed across the board:

• Nguyen’s testimony: The district court properly admitted pharmacist Thinh Nguyen as a lay witness under Rule 701 and did not abuse discretion under Rule 403, because Nguyen testified to factual observations and communications with Dr. Fung and did not offer expert conclusions about medical standards of care.
• Mistrial request: The district court acted within its discretion in denying a mistrial after the government’s medical expert, Dr. Timothy King, made a stray reference to a different patient (Y.E.) being “self-admitted addicted,” since the remark was “inadvertent, isolated, and ambiguous,” was not used against Dr. Fung, and did not prejudice the Count Seven verdict.
• Sufficiency of the evidence: A rational jury could find that Dr. Fung knowingly acted in an unauthorized manner when prescribing hydrocodone to Special Agent Fernandez, particularly given the recorded encounter and expert testimony describing the absence of examination, history, diagnosis, documentation, or treatment planning.
• $50,000 fine: The district court adequately considered the pertinent factors (including adopting the PSR’s financial findings) and permissibly imposed a within-guidelines fine.

III. Analysis

A. Precedents Cited

1. Lay vs. expert testimony (Rules 701/702) and the “nature of the testimony” inquiry

• Patterson v. Baker, 990 F.3d 1082 (7th Cir. 2021): Used to frame the basic distinction between lay opinions grounded in ordinary reasoning and expert opinions grounded in specialized knowledge, and to emphasize that lay testimony must be rooted in what the witness “saw, heard, or did.” The panel invoked Patterson to support the proposition that the admissibility question turns on whether the testimony is tethered to specialized knowledge (Rule 702) or everyday reasoning and perception (Rule 701).
• Chi. Joe's Tea Room, LLC v. Village of Broadview, 94 F.4th 588 (7th Cir. 2024): Cited for the Rule 701 elements and the acknowledgment that the line between lay and expert testimony “is not always sharp.” The court used Chi. Joe’s Tea Room to justify a functional approach: look to the content and reasoning process, not the witness’s résumé.
• United States v. Thomas, 970 F.3d 809 (7th Cir. 2020): Cited for the Rule 702 framework (qualification, helpfulness, reliable methods, sufficient facts/data). It served as the foil to explain what Nguyen did not do—he did not provide technical analysis or apply specialized methodology.
• United States v. Christian, 673 F.3d 702 (7th Cir. 2012): Quoted for the canonical distinction: lay testimony uses reasoning “familiar in everyday life,” whereas expert testimony requires reasoning mastered “only by specialists.” This concept anchored the holding that Nguyen’s testimony was within Rule 701 because it recounted transactions and communications rather than pharmacist-only analysis.
• United States v. Fenner, 142 F.4th 510 (7th Cir. 2025): Central to the panel’s treatment of “dual-hat” witnesses. Fenner is cited for the proposition that the distinction is between expert and lay testimony, not expert and lay witnesses, and that a person with expertise may still give lay testimony when speaking from personal perception rather than specialized inference. The panel used Fenner to reject the argument that Nguyen’s pharmacist status automatically converted his account into expert testimony.
• United States v. Malagon, 964 F.3d 657 (7th Cir. 2020): Cited to illustrate that participant understanding of a conversation can be lay testimony when it reflects ordinary comprehension rather than specialized knowledge. Nguyen’s testimony was treated similarly: he described what happened and what was said.
• United States v. Bowling, 952 F.3d 861 (7th Cir. 2020): Cited for the principle that testimony is lay (not expert) when it does not draw technical inferences or offer legal conclusions, but instead describes perception and contemporaneous reaction. Nguyen’s testimony was analogized to a perception-based account rather than a standards-based expert assessment.

2. Rule 403 deference and “unfair prejudice” standards

• United States v. Johnson, 89 F.4th 997 (7th Cir. 2024): Used for the appellate deference owed to district court evidentiary balancing under Rule 403, and the “no reasonable person” standard for reversal.
• United States v. LeShore, 543 F.3d 935 (7th Cir. 2008): Quoted via Johnson to reinforce that Rule 403 review is highly deferential.
• United States v. Dukes, 147 F.4th 711 (7th Cir. 2025) and United States v. Boros, 668 F.3d 901 (7th Cir. 2012): Cited for the reminder that most probative evidence is prejudicial; exclusion requires “unfair” prejudice that substantially outweighs probative value. This framing supported admitting Nguyen’s testimony as probative of knowledge and intent.

3. Mistrial standards: isolated remarks, prejudice, and curative instructions

• United States v. Lowe, 2 F.4th 652 (7th Cir. 2021): Cited for abuse-of-discretion review of mistrial denials.
• United States v. Bermea-Boone, 563 F.3d 621 (7th Cir. 2009) and United States v. Danford, 435 F.3d 682 (7th Cir. 2006): Used to emphasize “highly deferential” review because the trial judge is best positioned to gauge the incident’s seriousness in context.
• United States v. Hilliard, 851 F.3d 768 (7th Cir. 2017): Provided the substantive threshold: mistrial is appropriate when an event creates a real likelihood the jury cannot evaluate evidence fairly, depriving the defendant of a fair trial.
• United States v. Giannini, 104 F.4th 667 (7th Cir. 2024): Cited for the “harmful error” lens and the requirement of actual prejudice depriving a fair trial.
• United States v. Curry, 538 F.3d 718 (7th Cir. 2008): Key support for the proposition that “inadvertent, isolated and ambiguous” testimony does not warrant a mistrial.
• United States v. Diggs, 81 F.4th 755 (7th Cir. 2023) and United States v. Lane, 591 F.3d 921 (7th Cir. 2010): Both used to reinforce that fleeting objectionable testimony that is not repeated or exploited typically does not require a mistrial—especially where the rest of the evidence is strong.
• United States v. Lawrence, 788 F.3d 234 (7th Cir. 2015): Cited for the proposition that curative instructions are a common tool to mitigate prejudice, though the panel concluded none was required here (and the parties declined one).

4. Sufficiency review and prescriber mens rea under § 841(a)

• United States v. Jones, 79 F.4th 844 (7th Cir. 2023): Used for two propositions: (a) the “light most favorable to the government” evidentiary view; and (b) the sufficiency standard articulation in the Seventh Circuit.
• United States v. Shelton, 997 F.3d 749 (7th Cir. 2021): Cited for the “any rational trier of fact” standard.
• United States v. Leal, 72 F.4th 262 (7th Cir. 2023): Quoted via Jones for the “record is devoid of evidence” formulation and the “nearly insurmountable” burden for insufficiency claims.
• United States v. Moreno, 922 F.3d 787 (7th Cir. 2019) and United States v. Garcia, 919 F.3d 489 (7th Cir. 2019): Cited to caution that sufficiency analysis still polices irrational verdicts and that the hurdle depends on the government’s proof.
• Jackson v. Virginia, 443 U.S. 307 (1979): The foundational constitutional sufficiency standard, cited to anchor the analysis.
• United States v. Jones, 713 F.3d 336 (7th Cir. 2013): Cited alongside Jackson as part of the doctrinal chain on sufficiency.
• Ruan v. United States, 597 U.S. 450 (2022): The controlling Supreme Court precedent on prescriber prosecutions under § 841(a), requiring proof beyond a reasonable doubt that the prescriber knew or intended that they acted in an unauthorized manner (not merely that conduct was objectively unauthorized).

5. Fines and procedural sentencing explanations

• United States v. Johnson, 131 F.4th 811 (7th Cir. 2025): Cited for de novo review of procedural sentencing challenges.
• United States v. Lee, 950 F.3d 439 (7th Cir. 2020): The opinion’s main fine precedent. Lee was used to confirm that U.S.S.G. § 5E1.2 “mandates” a fine unless the defendant demonstrates inability to pay; that the defendant’s burden is heavy; that express findings on every factor are unnecessary; and that adoption of PSR facts can sufficiently support a fine decision—especially where PSR-reported assets exceed the fine.

B. Legal Reasoning

1. The “dual-hat” witness problem: why Nguyen stayed in Rule 701

Dr. Fung’s argument attempted a categorical rule: because Nguyen is a pharmacist, his testimony about verifying prescriptions and the pharmacy’s refusal to fill is necessarily “specialized knowledge.” The Seventh Circuit rejected that framing by applying the “nature of the testimony itself” approach (from Chi. Joe’s Tea Room and Fenner).

The district court preempted the Rule 701/702 boundary problem by narrowly cabining Nguyen’s testimony: he could recount volume, calls, communications, and the pharmacy’s decision; he could not testify about “conclusions” or “opinions.” That limitation mattered. The appellate court emphasized Nguyen did not opine on a medical standard of care or conclude Dr. Fung violated a standard—he described a real-world interaction that a non-expert coworker could have testified to if that person had made the call.

The decision therefore reads as a practical evidentiary blueprint: in prescriber cases, the government may introduce “notice” evidence (e.g., pharmacists flagging concerns) through lay testimony when the witness is functioning as a participant and narrator, not as an analyst applying technical criteria.

2. Rule 403: probative “knowledge” evidence versus “unfair prejudice”

On Rule 403, the court framed probative value around a contested element: Dr. Fung’s knowledge and intent. Nguyen’s testimony—particularly that he told Dr. Fung the pharmacy stopped filling prescriptions because they were issued monthly “without a clear treatment plan for the future”—supported an inference that Dr. Fung was alerted to concerns about his prescribing practices. That made the testimony directly relevant to whether Dr. Fung understood he was operating in an “unauthorized manner,” a theme that becomes more salient after Ruan.

The court also minimized prejudice by noting: (a) the government already had medical experts (Dr. Fleischer and Dr. King) to describe standards and impropriety; and (b) the district court’s tailored limitation ensured Nguyen did not become a backdoor standard-of-care expert. Under the deferential Rule 403 standard (Johnson), that was enough to affirm.

3. Mistrial: why one addiction reference did not “infect” Count Seven

The court’s mistrial analysis turned on context and prejudice. Although the district court had limited addiction evidence to what Dr. Fung knew, Dr. King referenced Y.E. as “self-admitted addicted.” The Seventh Circuit still affirmed the denial of a mistrial because the statement was (in the panel’s words) “inadvertent, isolated, and ambiguous” (tracking Curry), and it did not impute knowledge or wrongdoing to Dr. Fung.

Two additional prejudice-cutting facts did heavy lifting:

• The jury acquitted Dr. Fung on all counts tied to Y.E., suggesting the remark did not drive conviction decisions.
• The conviction count (Count Seven) involved the undercover visit, for which the government had recorded evidence and expert testimony—making the case on that count “overwhelming” (as in Diggs).

The court also noted a curative instruction was offered and declined by both parties, reinforcing that the trial court used an available mitigation tool even though the appellate panel deemed it unnecessary on these facts.

4. Sufficiency under § 841(a) after Ruan: proving subjective awareness from objective clinical irregularities

The sufficiency analysis applied Ruan v. United States: the government must prove beyond a reasonable doubt the defendant “knew” he was acting in an unauthorized manner or intended to do so. The Seventh Circuit held the evidence allowed that finding, focusing on what the jury saw and heard:

• Special Agent Fernandez said she had “discomfort,” emphasized she was “not in pain,” and described pills coming informally from other people.
• Dr. Fung warned about addiction and organ harm, said he did not “advise” taking narcotics, yet prescribed “some” because it was her “first time” there.
• He did so without vitals, history, examination, diagnosis, plan, documentation, or follow-up.
• Expert testimony characterized this as inconsistent with usual podiatry practice; Dr. King opined there was no legitimate medical purpose and it was outside the usual course of practice.

The panel also rejected Dr. Fung’s “inconsistent verdict” intuition (acquittals on 73 counts imply insufficiency on the 74th). The court treated the mixed verdict as evidence the jury discriminated among counts based on count-specific facts, and it distinguished other patients’ presentations and Dr. Fung’s conduct in those encounters (reports of pain, examinations, alternative treatments, refusal to prescribe to a girlfriend, and weaning).

Doctrinally, the opinion illustrates a post-Ruan evidentiary reality: subjective knowledge can be inferred from a constellation of objective irregularities (no exam, no documentation, no diagnosis, patient says “not in pain,” prescriber acknowledges narcotic dangers) when those irregularities are captured on recording and reinforced by expert explanation.

5. Fine procedure: adoption of PSR facts plus targeted § 5E1.2(d) considerations

On the fine, the court relied heavily on United States v. Lee. It reiterated three practical points:

• U.S.S.G. § 5E1.2 generally requires a fine unless the defendant proves inability to pay.
• The district judge need not make express findings on each § 5E1.2(d) factor.
• Adopting PSR facts can suffice, particularly where assets exceed the fine.

Here, the PSR showed Dr. Fung’s net worth exceeded the fine multiple times over; the parties agreed he could pay; and the district court explained deterrence, seriousness, and equitable considerations (including the opioid pandemic context and the fee collection point). That combination was adequate to affirm the $50,000 within-guidelines fine.

C. Impact

1. Evidentiary strategy in prescriber cases: “notice” evidence through pharmacist interactions

The most practically significant aspect of the decision is its clear approval of using pharmacist–prescriber communications as Rule 701 lay testimony when carefully limited. Prosecutors can treat pharmacist contacts and pharmacy refusals as “knowledge” evidence without necessarily triggering the procedural and methodological burdens of Rule 702 (and related criminal disclosures), so long as the witness is narrating firsthand interactions rather than offering professional judgments about medical legitimacy.

2. Trial management: mistrial remains an exceptional remedy

The mistrial discussion reinforces that even a violation of a pretrial evidentiary ruling does not automatically compel a new trial. The panel’s emphasis on whether the remark was exploited, whether it tied to the count of conviction, and whether the jury’s mixed verdict shows discrimination will likely be cited to resist mistrial motions arising from stray comments in multi-count controlled-substance prosecutions.

3. Post-Ruan proof: recordings plus clinical omissions can carry “subjective knowledge”

The opinion provides a roadmap for sufficiency in a post-Ruan world: juries can infer the required mens rea from a prescriber’s own words and the conspicuous absence of basic clinical steps, especially where the patient reports little to no pain and the prescriber acknowledges narcotic risks but prescribes anyway.

4. Sentencing fines: PSR adoption remains a robust explanation tool

The fine ruling signals that appellate courts will continue to accept relatively streamlined fine explanations when (a) the PSR contains detailed financial information, (b) the defendant can pay, and (c) the court articulates at least some punishment/deterrence rationale.

IV. Complex Concepts Simplified

• “Legitimate medical purpose” / “usual course of professional practice”: Under 21 C.F.R. § 1306.04(a), a prescription is “authorized” only if it is issued for a real medical reason and consistent with professional practice norms (e.g., assessment, diagnosis, documentation, treatment planning). In § 841(a) prosecutions, the government argues the prescriber stepped outside those boundaries.
• What Ruan changed: It is not enough to show a prescription was objectively improper; the government must prove the prescriber knew it was unauthorized or intended to act that way. Juries may infer knowledge from circumstances and the prescriber’s statements.
• Lay vs. expert testimony (Rules 701/702): Lay testimony is based on firsthand perception and everyday reasoning; expert testimony applies specialized knowledge to help the jury understand evidence. A professional (like a pharmacist) can still be a lay witness if he is describing what happened rather than offering technical conclusions.
• Rule 403 “unfair prejudice”: Evidence can hurt a party’s case and still be admissible; it becomes excludable only when the risk of unfair prejudice substantially outweighs probative value.
• Mistrial: A mistrial is a reset, granted only when a trial event likely prevented fair deliberation. Isolated, inadvertent remarks—especially not tied to the conviction count—typically do not justify this remedy.
• PSR adoption for fines: A judge can satisfy explanation duties by adopting a PSR’s detailed financial findings and stating a sentencing rationale, without separately reciting every statutory/guidelines factor.

V. Conclusion

United States v. Barnett K. Fung affirms a single-count § 841(a) prescriber conviction on recorded facts showing a narcotics prescription issued despite the patient’s lack of pain and without basic clinical safeguards, while clarifying two recurrent trial issues: (1) pharmacist–prescriber communications can be admitted as carefully limited lay testimony under Rule 701, and (2) a stray addiction reference, unexploited and untethered to the conviction count, does not compel a mistrial absent concrete prejudice. On sentencing, the decision reinforces that adopting PSR financial findings and articulating deterrence/seriousness considerations will usually suffice to uphold a within-guidelines fine under § 5E1.2.