Opinion by: Justice Groban (unanimous decision). Justice Liu filed a concurring opinion, in which Justice Evans concurred.

When a defendant presents substantial evidence of imperfect self-defense, the trial court’s failure to instruct on that theory precludes the jury from making a factual finding essential to prove the malice element of murder, and results in federal constitutional error. Schuller was convicted of first degree murder and found sane at the time of the killing. On appeal he argued the trial court’s refusal to instruct on imperfect self-defense was federal constitutional error. The Court of Appeal agreed the trial court erred in failing to so instruct, but found no prejudice under the state standard (People v. Watson (1956) 46 Cal.2d 818). The California Supreme Court granted review to decide the appropriate standard for evaluating prejudice in this context. Held: Reversed and remanded. Malice is an element of murder. But a finding of malice may be precluded, and the offense limited to manslaughter, when a person kills in the unreasonable but good faith belief in having to act in self-defense (imperfect self-defense). When imperfect self-defense is at issue in a murder case, the People must prove the absence of that circumstance to establish the element of malice. When there is substantial evidence to support the theory, the failure to instruct on imperfect self-defense amounts to an incomplete instruction on an element of murder, as it leaves the jury unable to properly evaluate whether the prosecution has sustained its burden to prove malice. This is constitutional error and is thus subject to review under the federal Chapman standard. (Chapman v. California (1967) 386 U.S. 18.) [Editor’s Notes: (1) The court noted that its holding applies to other forms of voluntary manslaughter, i.e., heat of passion and imperfect defense of others, which operate identically to imperfect self-defense by negating the malice element of murder. The court disapproved People v. Breverman (1998) 19 Cal.4th 142 and People v. Randle (2005) 35 Cal.4th 987 to the extent those cases could be read to hold otherwise. (2) The Supreme Court did not decide whether imperfect self-defense is available when “a defendant’s story is that a real person attacked him, but there are delusional components to the defendant’s description of what happened,” because the Attorney General did not raise this issue.]

The Court of Appeal’s prejudice analysis did not comport with Chapman. Although the Court of Appeal evaluated the instructional error under the state law standard, it went on to hold the error harmless even under Chapman. In the context of errors involving misdescription of an element of an offense, the Chapman standard compels the reviewing court to reverse the conviction unless no reasonable jury would have found in favor of the defendant on the missing fact. Here, the Court of Appeal’s harmless error analysis focused solely on what it characterized as overwhelming evidence that Schuller was not acting in any form of self-defense. The court “performed its own weighing of the evidence and its own assessment of witness credibility,” which are jury functions. This was not proper. “[I]f the court believed an instruction was warranted because there was sufficient evidence from which a reasonable jury could find in Schuller’s favor on the question of imperfect self-defense, the court could not then, consistent with Chapman, go on to find that the error was nonetheless harmless simply because the evidence against imperfect self-defense was so overwhelming that no reasonable jury could have possibly found in Schuller’s favor on that issue.” The case was remanded “to allow the court to reconsider whether the failure to instruct on self-defense was harmless beyond a reasonable doubt under the appropriate standard.” [Editor’s Note: In a concurring opinion, Justice Liu explained that he would hold reversible error occurred in this case and that he continues to disagree with the Supreme Court’s determination in People v. Elmore (2014) 59 Cal.4th 121, 130 (a closely divided decision), that a defendant may not argue imperfect self-defense based on a “purely delusional belief in the need to act in self-defense.” He suggested that the court reconsider Elmore in an appropriate case.]