In People v. Whitehurst (1992) 9 Cal.App.4th 1045, the defendant was charged with inflicting corporal punishment on a child resulting in a traumatic condition involving his stepdaughter and his son. His defenses at trial were that he was simply disciplining the stepdaughter and that he did not kick his son. He was acquitted of the count involving his son but was convicted of misdemeanor battery regarding his stepdaughter. On appeal he claimed the trial court had a sua sponte duty to instruct on a parent's right to discipline. The appellate court found that the trial court erred when it did not instruct on a parent's right to discipline. The court found "a parent has a right to reasonably discipline by punishing a child and may administer reasonable punishment without being liable for a battery." ( Id. at p. 1050.) A parent may not inflict unjustifiable punishment on a child. "Whether the corporal punishment falls within the parameters of a parent's right to discipline involves consideration of not only the necessity for the punishment but also whether the amount of punishment was reasonable or excessive." (Ibid.) The jury received no guidance on this concept. The concept was not self-evident. "Here the jury admittedly may have known that some parents do use corporal punishment to discipline a child without incurring either civil or criminal liability while others are subject to liability. But we cannot presume the jury knew when corporal punishment is lawful (and therefore a complete defense), or when it becomes a misdemeanor battery or when it forms the basis of a felony offense. Nor can we presume the jury knew that a parent's subjective belief that the punishment was necessary and reasonable and, therefore, justifiable does not preclude the jury from objectively determining that the punishment was either unnecessary or excessive." ( Id. at pp. 1050-1051.)