Upon reconsideration of murder conviction under a federal constitutional harmless error standard, Court of Appeal finds trial court’s failure to instruct on provocation that could have reduced murder to manslaughter reversible error. In 2012, the Court of Appeal affirmed Thomas’ second degree murder conviction, finding the trial court’s refusal to instruct on provocation that could have reduced murder to manslaughter was harmless error under the Watson standard, as applied in People v. Breverman (1998) 19 Cal.4th 142. The California Supreme Court transferred the case back to the Court of Appeal to decide whether the instructional error was federal constitutional error, as Thomas claimed the instructions were deficient under federal law. Held: Reversed. When malice is an element of murder and there is evidence of provocation, the federal due process clause requires the prosecution to disprove provocation beyond a reasonable doubt. Thomas requested CALCRIM No. 570, which informs the jury a murder is reduced to voluntary manslaughter if the defendant killed because of sudden quarrel or heat of passion. The court refused, giving a voluntary manslaughter instruction based on imperfect self-defense. This was error because there was substantial evidence that Thomas had a fight with the deceased and others just before the shooting and that he was angry because he had been beaten up. The Court of Appeal found its previous application of the Watson standard was error because the federal standard was not argued in Breverman, whereas Thomas raised a federal constitutional standard. In addition, the court should have instructed sua sponte with CALCRIM 522 (heat of passion may reduce a murder from first to second degree). The omission of the instructions may have affected the verdict, requiring reversal.