In jury trials, a challenge to the propriety of a jury instruction is a question of law. First State Bank of St. Charles, Missouri v. Frankel, 86 S.W.3d 161, 173 (Mo. Ct. App. 2002). On appeal, an appellate court will not reverse a jury verdict due to claimed instruction error — unless the error was “prejudicial.” Id. at 330. “Prejudice,” in this context, usually means that the error must materially affect the outcome of the action.
There are two general requirements for jury instructions. First, the instruction must be in accordance with the applicable law and claim. Romeo v. Jones, 144 S.W.3d 324, 330 (Mo. Ct. App. 2004). In other words, “[a]n instruction must be a correct statement of law.” Wieland v. Owner-Operator Servs., Inc., 540 S.W.3d 845, 857 (Mo. 2018). While Missouri Approve Instructions must generally be used, “[i]f a particular MAI does not state the law substantive law accurately, it should not be given.” Hervey v. Mo. Dep’t of Corr., 379 S.W.3d 156, 159 (Mo. 2012).
Second, to be given, an instruction must be supported by “substantial evidence.” Substantial evidence is evidence which, if true, is “probative of the issues and from which the jury can decide the case.” First State Bank, 86 S.W.3d at 173. When an instruction is disjunctive (i.e., present alternatives), all submissions must be supported by substantial evidence. Foster v. Barnes-Jewish Hosp., 44 S.W.3d 432, 435 (Mo. Ct. App. 2001).