Quentin Tarantino’s highly entertaining new film,Once Upon a Time….in Hollywood, retells the story of the murders committed by members of the Manson “family.” Charles Manson led a cult of followers who lived at the Spahn Ranch, a site in the hills of Los Angeles County where western TV shows such asThe Lone Rangerwere filmed. Members of the Manson clan committed nine murders during the summer of 1969. The most famous of the murders occurred at the home of Sharon Tate and her husband, the film director Roman Polanski. Tarantino’s retelling of the story has one of the cult killers say to her victims: “You taught me to kill. Shouldn’t I kill you?” This question is pointedly directed to members of the audience, too, asking viewers how to think about criminal guilt and responsibility.

This challenge may be what criminal law scholars call a “justification”: an argument that even though killing is prima facie morally wrong, under the circumstances it is permissible or even morally obligatory.

自卫是经典的辩护理由:当一个人有合理的理由相信有必要防止自己的死亡或严重的身体伤害时，使用武力在道德上是允许的。The scope of self-defense has been widened by“stand your ground” lawsthat remove the duty to retreat from threats if one can do so safely, as well as by court rulings that the belief does not need to be reasonable if it is sincerely held. Tarantino’s earlier film,Inglourious Basterds，他问观众杀害纳粹德国领导人是否合理。

Alternatively, the challenge may be what in criminal law is called an “excuse,” an argument that the actor should not be held criminally liable for his wrongful acts. Insanity is the classic excuse of this kind. Although it’s called a “defense,” this is misleading if it suggests that the act wasjustified, like self-defense. Rather, insanityexcusesthe offender from being judged subject to punishment, although she may still be subject to confinement to prevent her from harming others.

Approaches to theexcuse of insanityhave expanded and contracted. In some jurisdictions, the requirements of the crime are all that matters for punishment: did the supposed offender do the act, and with the requisite intent, recklessness, or negligence? On this view, explanations for why the actor did what he did are irrelevant to criminal liability. Someone who was so delusional that she did not realize she was shooting a gun at a person is not guilty of murder, because she lacked the relevant mental requirement for the offence as defined. But if she knew it was a person at whom she was aiming and pulled the trigger with unfortunate consequences for her victim, she is guilty and should pay the penalty, even if in the words of the Model Penal Codeshe lacks “substantial capacity” either to appreciate the criminality of her conduct or to conform her conduct to the requirements of the law.To be sure, during imprisonment she should receive whatever health care is appropriate for her, including mental health treatment—but her need for mental health treatment is irrelevant to whether she is guilty of the offense in the first place. What she did was bad or possibly even evil, and she should pay the price.

Increasing suggestions that there may be genetic explanations for psychiatric conditions have raised new questions about this separation of criminal liability from explanations of behavior. Research by colleagues of mine has found that evidence of psychopathy is a “double-edged sword” in the hands of judges: while they are inclined to reduce sentences when they are given evidence that the defendant has been diagnosed with psychosis, such sentence reductions appear to be offset by evidence that the psychosis may have a genetic explanation.

Others have argued that social conditions should serve as excuses. For example, advocates have contended that battered spouses should be excused from killing their batterers, even when they cannot claim self-defense. Tarantino’s character urges a new excuse of this kind: that the victim has created the offender. This is not the highly general claim that people who become violent because they have grown up in conditions of violence should be excused. Rather, the claim is specifically targeted to producers of influential and widely shared experiences of violent cultural objects: those they have taught to be violent by the experiences they have created should be excused from killing them.

That a generation who has grown up with widely shared experiences of violent video games such asMortal Kombatmight be excused for killing the game’s developer is a chilling thought. Tarantino himself has often been criticized for the violence in his films. But perhaps the more profound point of his films is getting us to think about the significance of the violence he has created.