United States v. Michael Thompson, 945 F.3d 340

Thompson sold heroin repeatedly to Bobby Mason, who acted as a middleman; on Oct. 6, 2017 Mason purchased heroin from Thompson and later used/injected it (directly or via Mason) with April Myers, who immediately collapsed and overdosed.
Paramedics administered Narcan and resuscitated Myers; hospital toxicology showed multiple drugs; ER physician Dr. Dizon testified that but for Myers’s use of heroin she would not have sustained serious bodily injury and that the heroin created a substantial risk of death.
A jury convicted Thompson of (1) distribution and possession with intent to distribute heroin resulting in serious bodily injury (21 U.S.C. § 841(b)(1)(C)) and (2) conspiracy; because of prior felony drug convictions Thompson received a mandatory life sentence on Count One.
Thompson moved for judgment of acquittal and a new trial; both motions were denied; he appealed arguing (a) insufficient evidence of but‑for causation, (b) § 841(b)(1)(C) requires proximate causation, and (c) the denial of a new trial based on witness credibility was erroneous.
The Fifth Circuit reviewed sufficiency de novo (with deference), reviewed the omitted instruction under plain‑error doctrine, and reviewed denial of a Rule 33 new trial for abuse of discretion.
Court affirmed: evidence supported but‑for causation; no plain error in failing to require/provide a proximate‑cause instruction; denial of new trial for credibility reasons was not an abuse of discretion.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Sufficiency of evidence for but‑for causation	Thompson: gov't failed to prove the heroin he supplied was the but‑for cause of Myers’s serious injury	Gov't: timeline, Narcan response, and Dr. Dizon’s opinion show heroin supplied by Thompson was a but‑for cause	Held: Evidence sufficient; reasonable juror could find but‑for causation
Whether § 841(b)(1)(C) requires proximate causation	Thompson: statute requires legal/proximate causation in addition to but‑for	Gov't: Burrage and subsequent authority require only but‑for/actual causation for the enhancement	Held: No proximate‑cause element; but‑for instruction was proper; circuits uniformly reject proximate‑cause requirement
Failure to instruct jury on proximate causation (plain‑error)	Thompson: omission was error affecting substantial rights	Gov't: omission not plainly erroneous given prevailing authority	Held: Plain‑error relief not available—error was not clear/obvious
Denial of new trial based on Mason’s credibility	Thompson: Mason was incredible/unreliable; warrants new trial	Gov't: credibility issues were explored at trial; jury is the fact‑finder; no basis to disturb verdict	Held: District court did not abuse discretion in denying Rule 33 motion

Burrage v. United States, 571 U.S. 204 (2014) (but‑for causation required where defendant’s drug was not independently sufficient to cause death)
United States v. Salinas, 918 F.3d 463 (5th Cir. 2019) (explains but‑for/actual causation standard)
United States v. Scott, 892 F.3d 791 (5th Cir. 2018) (standard for reviewing sufficiency of evidence)
United States v. Carbajal, 290 F.3d 277 (5th Cir. 2002) (treats §841 enhancement / analogous guideline as not imposing proximate‑cause requirement)
United States v. Harden, 893 F.3d 434 (7th Cir. 2018) (collects authority rejecting proximate‑cause element under §841(b))
United States v. Webb, 655 F.3d 1238 (11th Cir. 2011) (rejects proximate causation requirement for §841(b))
United States v. Cotton, 535 U.S. 625 (2002) (sets plain‑error review framework for unpreserved trial objections)
United States v. Robertson, 110 F.3d 1113 (5th Cir. 1997) (standard for appellate review of district court denial of Rule 33 new trial)
United States v. Ramos‑Delgado, 763 F.3d 398 (5th Cir. 2014) (interprets "resulted from" language as requiring actual/but‑for causation)