Does a court have a sua sponte duty to instruct on the defense of justifiable homicide?

A court has a sua sponte duty to instruct on the defense of justifiable homicide when "'it appears that the defendant is relying on such a defense,'" or if "'there is substantial evidence supportive of such a defense and the defense is not inconsistent with the defendant's theory of the case.'" (People v. Breverman (1998) 19 Cal.4th 142, 157, abrogated on another ground by amendments to 189.) Here, defense counsel was explicitly relying on a justifiable homicide defense, so the instruction was required.