Justification: Self-Defense

American law does not require an actual threat of aggression to trigger the right to use force in self-defense, but does require a belief in the necessity of force. This has two ramifications. First, one who uses force against another without the belief that the other poses a threat, when in fact the other is a threat, is not eligible to be justified in self-defense. Second, and more importantly, a defender who mistakenly believes that another poses a threat and uses force against that threat is still eligible to be justified in self-defense. As to the latter case, at issue is just what sort of belief suffices, or alternatively what sort of mistake is acceptable.

The MPC appears to require merely a plain belief and thus allows any mistake. But section 3.09(2) provides that where the mistake is reckless or negligent, a defendant will not be eligible for the defense when charged with an offense in which recklessness or negligence suffices to establish culpability. For those offenses, only a reasonable belief or mistake will establish the defense. But if charged with an offense requiring a higher level of mens rea, even an unreasonable belief or mistake as to the necessity of using force will suffice.

The general approach of the common law and modern statutes is simply to allow the defense if the belief or mistake is reasonable. This is criticized from both sides. Glanville Williams argued for the standard of honest belief because otherwise a negligent or reckless mistake will be punished as an intentional offense. On the other hand, Fletcher and Paul Robinson maintain that even reasonable belief is insufficient; an actual threat is required.

To determine the reasonableness of a belief, the standard is whether a reasonable person in the defendant's situation would believe the use of force necessary. But how much of the circumstances, experiences, and attributes of the defendant should be attributed to the reasonable person? If too much is included—subjectifying the standard to the extent it could become the unreasonable reasonable person standard—the standard becomes meaningless, but if not enough of the defendant's situation is included, the standard may be unfair.

Consider two cases that struggled with this issue. Bernhard Goetz, dubbed the "subway vigilante," shot four African American youths after some of them asked him for five dollars (People v. Goetz, 497 N.E.2d 41 (N.Y. 1986)). Claiming that their conduct was the prelude to an armed robbery, Goetz claimed that he acted in reasonable self-defense. In determining whether a reasonable person would have acted as Goetz did, should Goetz's three prior muggings, the prevalence of crime in the New York City subway, and Goetz's beliefs and attitudes about his claimed attackers' race, apparel, sex, and age be included? If so, the standard risks degenerating to what a reasonable racist would have done in the situation. On the other hand, assume arguendo that Goetz's views on race and crime were empirically justified; does that make his conduct more reasonable?

In another case, Wanrow, a short woman with a broken leg and using crutches, shot and killed in her home Wesler, a large, inebriated man (State v. Wanrow, 559 P.2d 548 (Wash. 1977)). Though not presently attacking her when she shot him, she claimed that he had startled her. Are Wanrow's suspicions that Wesler had attempted to sexually molest her son, did molest her neighbor, and had been in a mental institution to be attributed to the reasonable person? Additionally, is the reasonable person a large, athletic man or a short, slight, woman on crutches?

What the defendant's situation is meant to include is, according to the MPC, purposely ambiguous so as to leave the issue open to jurors and/or courts to decide. Although most courts have avoided the complete subjectivization of the standard, a considerable amount of the defendant's situation is included. As the Goetz court explained, a reasonable person in the defendant's situation may consider:

the physical movements of the potential assailant [,] . . . any relevant knowledge the defendant has about that person [and,]. . .the physical attributes of all persons involved, including the defendant. Furthermore, the defendant's circumstances encompass any prior experiences he had which could provide a reasonable basis for the belief that another person's intentions were to [attack] . . . him or that the use of deadly force was necessary under the circumstances. (Goetz, p. 52)

Though this standard leaves open many questions, the law will continue to grapple with the issue as it lurches toward a consensus.