A man who shoots a woman, unlawfully and intentionally causing her death, is guilty of the woman’s murder, of course. If the woman is some 12 weeks pregnant, and the fetus also dies, is the man also guilty of murdering the fetus even though he did not intend to kill the fetus and did not even know of its existence?
A person may be convicted of murder of another human being on a theory of implied malice, which requires only proof of causing the victim’s death by an intentional act, the natural consequences of which were dangerous to human life, with knowledge of that danger. (People v. Lasko (2000) 23 Cal.4th 101, 107 [96 Cal.Rptr.2d 441, 999 P.2d 666].) The majority asserts, *872however, that for a conviction of implied malice murder of a fetus, it is sufficient that the person acted with conscious disregard “for life in general” (maj. opn., ante, at p. 869). I disagree.
The Legislature has carefully defined murder in terms of two distinct classes of victims—human beings and fetuses. The majority’s reasoning effectively abrogates this important distinction by the manner in which it defines the mental state requirements for implied malice fetal murder. Instead of requiring proof of implied malice toward a particular fetus or fetuses in general, the majority requires only proof of implied malice toward “life in general.” (Maj. opn., ante, at p. 869.)
In my view, however, a defendant is guilty of murdering a fetus on an implied malice theory only if the fetus’s death resulted from the defendant’s intentional act, the natural consequences of which were dangerous to fetal life, with knowledge of that particular danger.
L
I begin with a brief overview of the relevant law.
“Murder is the unlawful killing of a human being, or a fetus, with malice aforethought.” (Pen. Code, § 187.)1 Felony murder aside, malice—either express or implied—must be present for a killing to be murder. “Malice exists” if the “unlawful homicide was committed with the ‘intention unlawfully to take away the life of a fellow creature’ (§ 188), or with awareness of the danger and a conscious disregard” for the risk to life. (People v. Rios (2000) 23 Cal.4th 450, 460 [97 Cal.Rptr.2d 512, 2 P.3d 1066].)
An “unlawful killing of a human being without malice” is manslaughter. (§ 192.) Certain types of provocation will “reduce an intentional, unlawful killing from murder to voluntary manslaughter ‘by negating the element of malice.’ ” (People v. Rios, supra, 23 Cal.4th at p. 461, quoting People v. Breverman (1998) 19 Cal.4th 142, 154 [77 Cal.Rptr.2d 870, 960 P.2d 1094].) “A defendant lacks malice and is guilty of voluntary manslaughter in ‘limited, explicitly defined circumstances’ ” (People v. Blakeley (2000) 23 Cal.4th 82, 87 [96 Cal.Rptr.2d 451, 999 P.2d 675]), for example, when the defendant acts in a “sudden quarrel or heat of passion” (§ 192, subd. (a)).
Fetal murder is a relatively new crime in California. Beginning in 1850, our law defined murder as “the unlawful killing of a human being, with malice aforethought.” (Stats. 1850, ch. 99, § 19, p. 231.) In 1970, the *873Legislature amended that statutory definition by including “a fetus” in the definition of murder. (§ 187, as amended by Stats. 1970, ch. 1311, § 1, p. 2440.)
The amendment was in response to our decision earlier that year in Keeler v. Superior Court (1970) 2 Cal.3d 619 [87 Cal.Rptr. 481, 470 P.2d 617]. In that case, the former husband of Teresa Keeler accosted her in a remote location, and upon seeing her obvious pregnancy said he was “going to stomp it out of you.” (Id. at p. 623.) He attempted to do just that, causing the death of a five-pound female fetus. Teresa Keeler survived. When charged with murder of the fetus, the defendant contended he could not be prosecuted for fetal murder because the fetus had not been bom alive and therefore was not a “human being” under our statute, which defined murder as the unlawful killing of “a human being.” This court agreed, observing that in 1850, when the Legislature first enacted a statute defining murder, it had followed the common law rale that killing an unborn, but viable, fetus was not murder. (Id. at pp. 627-628, 637-638.) Because California had never created a crime of feticide, this court concluded in Keeler that the defendant could not be tried for the murder of the fetus. (Id. at pp. 628-631.) Dissenting in Keeler, Justice Burke would have permitted a prosecution for fetal murder, reasoning that the statutory term “human being” should be construed as including the killing of a viable fetus. (Keeler v. Superior Court, supra, 2 Cal.3d at pp. 641-645 (dis. opn. of Burke, J.).)
In response, the Legislature amended the murder statute by adding a second category of murder victim, defined only as “a fetus.”2 At the same time, the Legislature rejected a proposal to add the killing of a fetus to the definition of manslaughter. (§ 192; Comment, Is the Intentional Killing of an Unborn Child Homicide? California’s Law To Punish the Willful Killing of a Fetus (1971) 2 Pacific L.J. 170, 172-174.) Thus, California does not recognize a crime of fetal manslaughter; “only the unlawful killing of a human being can constitute manslaughter.” (People v. Dennis (1998) 17 Cal.4th 468, 506 [71 Cal.Rptr.2d 680, 950 P.2d 1035]; see People v. Brown (1995) 35 Cal.App.4th 1585, 1592 [42 Cal.Rptr.2d 155].)
H.
The majority starts from an unremarkable premise: A defendant who “commits an act, the natural consequences of which are dangerous to human life,” with a mental state of conscious disregard for that risk, acts with implied malice toward any human beings who die as a consequence. (Maj. *874opn., ante, at p. 868.) It then states: “There is no requirement the defendant specifically know of the existence of each victim.” (Ibid.) To illustrate that point, the majority gives various scenarios in which a defendant fires a gun in or at an occupied apartment within a multi-unit building, killing human beings of whose presence he was unaware. It is an interesting exercise, but one that has no relevance to the issue before us. What needs to be determined here is the required mental state for implied malice murder of a fetus, and more specifically whether the mental state is identical to the mental state required for implied malice murder of a human being.
The majority asserts that when a defendant, aware of the risk, commits an act whose natural consequences are dangerous to human life, with a mental state of “a conscious disregard for life in general,” he has committed implied malice murder. (Maj. opn., ante, at p. 868.) In sum, the majority concludes that conscious disregard “for life in general”—by which it apparently means human life as well as fetal life—is a sufficient mental state for implied malice murder of both human beings and fetuses, the two categories of murder victims specified in section 187, which defines murder. In essence, the majority holds that one whose mental state is a generalized conscious disregard for life bears that same mental state toward all “potential victims” (maj. opn., ante, at p. 869), even those of whom the actor is not aware.
The rule articulated by the majority may or may not be what the Legislature intended. But the majority neither acknowledges the breadth of the rule it has fashioned, nor does the majority explain why that rule is compelled by the Legislature’s 1970 amendment to section 187, which added fetuses as victims of murder.
III.
As noted above, California recognizes two categories of murder victims— human beings and fetuses. (§ 187.) It is unclear whether the state Legislature intended to create a single crime of murder applicable to both a human being and a fetus, or whether it intended to create two crimes—murder of a human being and murder of a fetus.3 The question arises in part because the Legislature, when it amended section 187 to include a fetus as a murder victim, considered but ultimately rejected a proposal to recognize a crime of fetal manslaughter. As a result, there is a nonparallel punishment scheme for killings of human beings and for killings of fetuses, as discussed below.
*875“When a killer intentionally but unlawfully kills in a sudden quarrel or heat of passion, the killer lacks malice and is guilty only of voluntary manslaughter.” (People v. Lasko, supra, 23 Cal.4th at p. 104.) The effect of omitting a crime of fetal manslaughter is evident in the following scenario: A man comes home and finds his wife in bed with another man. Grabbing a handgun from the nightstand, he shoots his wife, killing her, unaware that his wife is nine weeks pregnant. Her death causes the death of the fetus. He is charged with the murders of his wife and the fetus. At trial he presents a defense of having acted in the heat of passion. The jury believes him, finding him guilty of the lesser offense of manslaughter for his wife’s death. With respect to the dead fetus, the jury, having been instructed by the trial court that California has no crime of fetal manslaughter, and having found that defendant acted with provocation, which negates malice, cannot legally convict defendant of murder. Nor can it legally convict him of a lesser offense of manslaughter, because there is no crime of fetal manslaughter. Thus the killer, despite his mental state of conscious disregard for life in general, is liable only for the death of his wife (manslaughter) but not for the death of the fetus (no crime).
The lack of parallel punishment for killing a human being and killing a fetus suggests that the Legislature did not intend the crime of fetal murder to parallel that of murder of a human being. To the extent California’s homicide law “attempts to sort killings according to the culpability they reflect” (Mounts, Malice Aforethought in California (1999) 33 U.S.F. L.Rev. 313, 314), the fact that the same murderous conduct is punished differently depending upon the type of victim, either a human being or a fetus, implies that the Legislature intended to treat fetal murders differently. If murder of a fetus is not the same crime as murder of a human being, is the mental state for murder of a fetus different from the mental state required for murder of a human being? After much thought and considerable research, I cannot answer the question. The Legislature has given no clue what it intended in this regard.
In attempting to answer the question just posed, one must recognize the biological fact that for a considerable time a fetus’s presence in its mother’s womb may not be readily apparent to others. What, then, is the required mental state when one kills the fetus of a woman who shows no outward signs of pregnancy, and the killer’s conduct or expressions of intent do not permit the inference that he acted with express malice toward the fetus? Those are the cases that are difficult to grapple with. Far easier are the cases in which the defendant’s actions show express malice toward the fetus. In the latter category is the defendant in Keeler v. Superior Court, supra, 2 Cal.3d at page 623, who exhibited express malice toward the fetus, both by stating his intent to “stomp” the fetus out of his pregnant former wife’s belly and by proceeding to do just that. Similarly, the defendant in People v. Dennis, supra, 17 Cal.4th 468, demonstrated express malice toward the fetus when he *876used a machete to attack his eight-months pregnant former wife, delivering such ferocious blows that he killed her and the fetus she was carrying by inflicting wounds to the wife’s abdomen that cut into the fetus’s torso, transecting its heart and severing its left leg. (Id. at pp. 489, 508, 515.)
The more difficult cases are those in which the defendant’s mental state could at most be described as implied malice, as in the situation here. Malice is implied “when no considerable provocation appears, or when the circumstances attending the killing show an abandoned and malignant heart.” (§ 188.) To put it simply, one who acts with implied malice “necessarily acts with knowledge of the life-threatening harm that might occur if he proceeds with ‘an act with a high probability that it will result in death.’ ” (People v. Dellinger (1989) 49 Cal.3d 1212, 1219 [264 Cal.Rptr. 841, 783 P.2d 200].)
The prosecution’s theory at trial was that when defendant shot and killed his former girlfriend, Patty Pansier, in an occupied apartment building, he acted with conscious disregard not only for her safety but for the safety of any human beings who might be in the building. This trial theory derives from the “zone of harm” rationale that this court described in People v. Bland (2002) 28 Cal.4th 313, 329 [121 Cal.Rptr.2d 546, 48 P.3d 1107]: “Where the means employed to commit the crime against a primary victim create a zone of harm around that victim, the factfinder can reasonably infer that the defendant [had the actual intent to kill] all who are in the anticipated zone.” (Italics added.) Indeed, the majority here relies on two Court of Appeal zone-of-harm cases, one dating from 1913 and the other from 1985, for the proposition that a defendant will be liable for the death of any victim, even a victim of whose existence the defendant is unaware. (See maj. opn., ante, at p. 868, citing People v. Stein (1913) 23 Cal.App. 108 [137 P. 271] [the defendant shot repeatedly into a group of dancers in a public room of a hotel, killing one of them]; and People v. Albright (1985) 173 Cal.App.3d 883 [219 Cal.Rptr. 334] [the defendant, while drunk, drove at high speed, hitting and killing another driver of whose presence the defendant was unaware until moments before the collision].) The prosecution sought to apply the zone-of-harm model to the facts here. In doing so, it implicitly equated a human victim occupying an apartment in a multi-unit building with a fetal victim occupying its mother’s body.
But the rule fashioned today by the majority is far broader than the prosecution’s zone-of-harm theory used at trial. The only mental state the majority requires for implied malice murder of a fetus is that the defendant commit an act whose natural consequences endanger “life in general” or “all life, fetal or otherwise.” (Maj. opn., ante, at pp. 868, 870.) Thus, the majority implicitly concludes that the crime of fetal murder may be committed by one who acts only with conscious disregard for human victims, even when the *877actor’s conduct kills no living human being, but causes the death of a fetus. Under the majority’s rule, when one commits an act directed at a female victim and does so with an awareness that it carries a substantial risk to her life, that mental state suffices to establish implied malice murder of a fetus in her womb whose existence is neither apparent nor known to the actor. Suppose that defendant, while alone with Patty Pansier in the apartment, had beaten her severely, putting her life in peril. Suppose defendant did not know that Pansier was carrying three 12-week-old fetuses. And suppose that although Pansier recovered from her injuries, the beating caused the death of her three fetuses. Under the majority’s holding, defendant in this scenario would be liable for the implied-malice second degree murder of each of the three fetuses, of whose existence defendant was ignorant, based entirely on his mental state of implied malice toward life in general when he attacked Pansier.
It is unclear whether the 1970 Legislature in amending the murder statute by adding “a fetus” intended only to expand the victims of murder to include human beings and fetuses but to retain the same mental state for both types of victim. In amending section 187 by defining murder as the unlawful killing of a human being or a fetus, the Legislature did not add language such as, “For purposes of this section a human being includes a fetus.” Nor did it make fetal manslaughter a crime. What exactly the Legislature intended is unclear. I urge the Legislature to revisit the criminal laws applicable to fetal killings to resolve the uncertainties in this difficult area.
When interpreting a law defining a crime, and the statutory language is susceptible to two equally reasonable constructions, it is the policy in this state to construe the statute in the defendant’s favor lest defendants not have fair warning of what conduct is prohibited. (People v. Avery (2002) 27 Cal.4th 49, 57-58 [115 Cal.Rptr.2d 403, 38 P.3d 1]; People v. Gardeley (1996) 14 Cal.4th 605, 622 [59 Cal.Rptr.2d 356, 927 P.2d 713].) Absent some clear indication of what mental state the Legislature intended for implied malice murder of a fetus, I would hold that a defendant who neither knows nor has reason to suspect that his female victim is pregnant, is not liable for the implied malice murder of a fetus who dies as a result of a murderous attack on the fetus’s mother.
I would affirm the Court of Appeal’s judgment reversing defendant’s conviction for the second degree murder of Fansler’s fetus.
Appellant’s petition for a rehearing was denied June 23, 2004. Kennard, J., was of the opinion that the petition should be granted.
All further statutory references are to the Penal Code.
A fertilized egg becomes a fetus under section 187 “ ‘after major structures have been outlined,’ ” or about seven to eight weeks after fertilization. (People v. Davis (1994) 7 Cal.4th 797, 810 [30 Cal.Rptr.2d 50, 872 P.2d 591].)
Recently, Congress enacted a federal statute creating two separate crimes: one against the mother, the other against “the unborn child.” (Unborn Victims of Violence Act of 2004, Pub.L. No. 108-212 (Apr. 1, 2004) 118 Stat. 568.)