State of Iowa v. Justice Mathis, 971 N.W.2d 514

Justice Mathis was tried and convicted on three counts of second-degree sexual abuse for alleged acts against two children (B.T. and L.S.) that occurred between Oct. 2015 and Nov. 2017 while they visited his grandparents' home.
B.T. (age 7–9 during the timeframe) testified Mathis had vaginal intercourse with her once; L.S. (age 5–7) testified Mathis engaged in anal intercourse with him on more than one occasion; neither could give exact dates.
No physical evidence corroborated the children’s accounts; forensic exams were negative. The children disclosed the abuse after other inappropriate conduct was observed and after being interviewed at a child protection center.
Mathis denied all wrongdoing; testimony from his grandmother suggested the children were generally discouraged from entering his bedroom but she was hospitalized several times and could not always observe the bedroom area.
At trial the district court instructed the jury that the testimony of an alleged sexual‑offense victim need not be corroborated; the prosecutor emphasized this instruction in closing argument.
The Iowa Court of Appeals affirmed. The Iowa Supreme Court granted further review, upheld sufficiency of the evidence, but found the noncorroboration instruction improper and prejudicial, vacating the convictions and remanding for further proceedings.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Sufficiency of evidence to support sexual‑abuse convictions	Victim testimony and marshaling instructions (sex act + victim under 12) are sufficient; view evidence in light most favorable to State	Victim testimony was inconsistent, possibly conflated with abuse by another defendant, and thus insufficient as a matter of law	Evidence was sufficient; jury verdict supported by substantial evidence and credibility choices are for the jury
Validity of noncorroboration jury instruction (“no requirement that testimony of alleged victim be corroborated”)	Instruction permissible and consistent with law (court cited Kraai)	Instruction violated statutory and fairness concerns by singling out victim testimony and unfairly emphasizing it	Instruction was improper because it unduly emphasized complainants’ testimony; error was prejudicial; convictions vacated and case remanded

State v. Kraai, 969 N.W.2d 487 (Iowa 2022) (controls on noncorroboration instruction and explains when such instruction improperly accentuates victim testimony)
State v. Donahue, 957 N.W.2d 1 (Iowa 2021) (standards for reviewing jury instructions and sufficiency principles)
State v. Jones, 967 N.W.2d 336 (Iowa 2021) (standard of review for sufficiency of evidence)
State v. Tipton, 897 N.W.2d 653 (Iowa 2017) (definition of substantial evidence and deference to jury verdicts)
State v. Musser, 721 N.W.2d 758 (Iowa 2006) (appellate limits on reweighing evidence or assessing witness credibility)
State v. Smith, 508 N.W.2d 101 (Iowa Ct. App. 1993) (outlier decision where victim testimony was rejected as legally insufficient)
State v. Hanes, 790 N.W.2d 545 (Iowa 2010) (presumption of prejudice when an instruction error is made and burden to show no prejudice)
State v. Plain, 898 N.W.2d 801 (Iowa 2017) (harmless‑error framework for jury‑instruction errors)