California Case Law on Heat of Passion
The California Supreme Court explained in People v. Steele (2002) 27 Cal.4th 1230, "the heat of passion requirement for manslaughter has both an objective and a subjective component. The defendant must actually, subjectively, kill under the heat of passion. But the circumstances giving rise to the heat of passion are also viewed objectively. As we explained long ago in interpreting the same language of section 192, 'this heat of passion must be such a passion as would naturally be aroused in the mind of an ordinarily reasonable person under the given facts and circumstances,' because 'no defendant may set up his own standard of conduct and justify or excuse himself because in fact his passions were aroused, unless further the jury believe that the facts and circumstances were sufficient to arouse the passions of the ordinarily reasonable man. '" (27 Cal.4th at pp. 1252-1253.)
Also in People v. Lee (1999) 20 Cal.4th 47, the court noted that, "although section 192, subdivision (a), refers to 'sudden quarrel or heat of passion,' the factor which distinguishes the 'heat of passion' form of voluntary manslaughter from murder is provocation. The provocation which incites the defendant to homicidal conduct in the heat of passion must be caused by the victim , or be conduct reasonably believed by the defendant to have been engaged in by the victim. The provocative conduct by the victim may be physical or verbal, but the conduct must be sufficiently provocative that it would cause an ordinary person of average disposition to act rashly or without due deliberation and reflection. " (Id. at p. 59.)
CALJIC No. 8.42 (California jury instructions) provides, in relevant part:
"To reduce an unlawful killing from murder to manslaughter upon the ground of sudden quarrel or heat of passion, the provocation must be of the character and degree as naturally would excite and arouse the passion, and the assailant must act under the influence of that sudden quarrel or heat of passion. The heat of passion which will reduce a homicide to manslaughter must be such a passion as naturally would be aroused in the mind of an ordinarily reasonable person in the same circumstances. . . . The question to be answered is whether or not, at the time of the killing, the reason of the accused was obscured or disturbed by passion to such an extent as would cause the ordinarily reasonable person of average disposition to act rashly and without deliberation and reflection, and from passion rather than from judgment."