United States v. Carpenter, ACM 38995

Appellant, an adult service member, responded to a Craigslist posting and met JM, a 13‑year‑old, after Skype communications; they engaged in mutual fellatio and anal intercourse.
Appellant was tried by general court‑martial, convicted contrary to his pleas of sexual assault of a child (Article 120b), and sentenced to a dishonorable discharge, two years confinement, forfeitures, and reduction to E‑1.
Appellant conceded the acts occurred but asserted an honest and reasonable mistake‑of‑fact defense: he testified he believed JM represented himself as 19 and appeared older.
Government evidence included JM’s statements to Appellant that he was 19–20, inconsistencies (Appellant knew indicators inconsistent with an adult in base housing), and an AFOSI agent’s testimony that Appellant lied about the sexual contact.
Trial hinged on witness credibility and JM’s appearance/demeanor; the military judge excluded defense proffers of JM’s later Craigslist messages and testimony about JM’s other sexual partners under Mil. R. Evid. 412.
The Air Force Court of Criminal Appeals reviewed legal and factual sufficiency de novo and review of the Rule 412 ruling for abuse of discretion, and affirmed findings and sentence.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Legal & factual sufficiency of convictions	Prosecution: evidence showed JM’s age and Appellant’s guilt beyond a reasonable doubt	Appellant: claimed honest, reasonable mistake that JM was ≥16 (believed JM said 19)	Affirmed; reasonable factfinder could reject mistake defense; appellate court independently convinced beyond a reasonable doubt
Admissibility under Mil. R. Evid. 412 of JM’s later Craigslist messages and testimony about other men	Appellant: messages and other men’s conduct show JM’s sexual sophistication and corroborate Appellant’s claim he was deceived about age	Government: messages were posted after the encounter and Appellant had no knowledge of them, so they were irrelevant to his belief at the time	Affirmed exclusion; evidence irrelevant to mistake‑of‑fact because admissibility turns on facts known to Appellant at the time; no abuse of discretion

United States v. Washington, 57 M.J. 394 (appellate de novo review standard for sufficiency)
United States v. Humpherys, 57 M.J. 83 (legal sufficiency standard)
United States v. Turner, 25 M.J. 324 (factual sufficiency test)
United States v. Goodman, 70 M.J. 396 (mistake‑of‑fact must be honest and reasonable)
United States v. Dorsey, 16 M.J. 1 (materiality definition)
United States v. Ellerbrock, 70 M.J. 314 (Mil. R. Evid. 412 and confrontation/cross‑examination issues)
United States v. Gaddis, 70 M.J. 248 (412 balancing/test for probative value vs. prejudice)