When does undisclosed evidence meet the Brady materiality standard on appeal? State v. Marx Explained

Background and facts

Trevor Marx was convicted of sodomy upon a child and witness tampering following a jury trial in the Fifth District Court. The charges arose from his daughter Taylor’s disclosure that Marx had sexually abused her when she was a young child. During a recorded pretext call arranged by police, Marx told Taylor three separate times that he would “prefer” she not report the abuse, twice noting he could “get into a lot of trouble.” After trial and with new counsel, Marx learned the State had not disclosed body camera footage of the victim’s mother’s initial police interview or a Safe and Healthy Families physical examination report. He moved for a new trial and also claimed trial counsel was ineffective for failing to obtain those materials and for not presenting medical evidence of his asserted chocolate allergy — a central defensive theory given that Taylor testified Marx had put chocolate sauce on his penis.

Key legal issues

The appeal presented three questions: (1) whether the State’s failure to disclose the body camera footage and the physical examination report constituted a Brady violation; (2) whether trial counsel rendered ineffective assistance of counsel under Strickland v. Washington by failing to obtain those materials or present allergy evidence; and (3) whether Marx was entitled to a rule 23B remand to supplement the record with forensic expert testimony on childhood memory and false allegations.

Court’s analysis and holding

The Utah Court of Appeals affirmed on all grounds. On the Brady claim, the court applied the three-part test requiring suppression, favorability, and materiality — defined as a reasonable probability of a different result had the evidence been disclosed. Evaluating the cumulative effect of both items, the court found neither material. The body camera footage would have simultaneously helped and hurt Marx because it would have revealed the reason for the mother’s repeated questioning: Marx’s second ex-wife had repeatedly expressed concerns about his behavior toward Taylor. The physical examination report, showing no injuries, was unsurprising given the abuse had ended five years before the examination.

Critically, the court emphasized that this was not a simple credibility contest. The pretext call — in which Marx never denied the abuse and repeatedly urged Taylor to stay silent — and his implausible trial testimony that he was never alone with his daughter during a five-year period when he was her primary daytime caregiver created independent, substantial credibility problems that no undisclosed evidence could have overcome.

On the ineffective assistance claims, the court noted that the prejudice standard under Strickland is functionally identical to the materiality standard under Brady, so the Brady analysis disposed of the parallel IAC claim. As to the allergy evidence, Marx’s self-conducted experiment and skin prick test showed only mild sensitivity — directly contradicting his and his father’s trial testimony describing anaphylactic reactions. Presenting that evidence would have undermined rather than supported the defense. The failure to call a medical expert was speculative because no specific expert or proposed testimony was identified in the record. The rule 23B request failed for the same reason: the proposed forensic expert’s testimony about childhood memory and false allegations would not have explained away Taylor’s detailed corroborated recollections or overcome the pretext call evidence.

Practice implications

Practitioners should note that Brady materiality and Strickland prejudice are evaluated cumulatively against the entire trial record — not in isolation. When the record contains powerful independent evidence of guilt, such as a recorded pretext call, courts will assess whether any omitted evidence could realistically have changed the jury’s calculus. Additionally, practitioners pursuing IAC claims based on uncalled expert witnesses must identify the expert, proffer the expected testimony, and — if that record does not exist — seek a rule 23B remand with a sufficiently specific, nonspeculative factual basis. Vague assertions that a qualified expert “could” have testified are consistently rejected as speculative.