Justification: Necessity

Self-defense and legal authority. Commentators have taken contrasting positions on the relation of necessity to other defenses. The Model Penal Code says that it expresses the overarching principle behind legal justification. Other commentators such as P. R. Glazebrook have argued that it is an interstitial concept, designed to fill gaps between other established defenses.

The Code position is easy to understand. If we consider harmful acts that are legally justified because of authority—for example, a policeman assaulting or wounding an escaping felony suspect—the rule that justifies the policeman's act seems to reflect a general conviction that less harm overall is brought about by the coercive acts of the police than would be caused by unrestrained offenders in such contexts. The battery by the policeman is therefore the lesser evil.

Similarly, self-defense can be redescribed as justification based on lesser evils. Less harm overall may be said to occur when persons who are threatened with harm are allowed to respond with force sufficient to repel the threat than when they are not legally empowered to do so. Arguably, even when the choice is between two lives, between the homicidal aggressor and the defending victim, the use of deadly force by the victim manifests less evil than the completion of the original aggression.

The drafters of the Model Penal Code therefore conclude that the necessity defense embodies the general principle of justification. Accordingly, a lesser evils defense should be available as justification whether or not harmful conduct happens to fall under a more specialized defense such as authority or self-defense. The difficulty with this argument, as critics such as Brudner point out, is that it is one thing to say that such circumscribed defenses as authority and self-defense are justified at a more general level by reference to the goal of minimizing harm, and it quite another matter to argue that the disposition of particular cases should turn on judgments about relative harm made by individuals faced with hazard. The first is a rule-utilitarian application of the lesser evils analysis to explain familiar defenses; the latter turns it into an act-utilitarian mode of justification.

It is also clear that authority and self-defense are not simply subcategories or instantiations of the general justification of lesser evils. Some situations, for example, fit the criteria of self-defense even if they are hard to justify in terms of lesser evils. In such cases, the harm to the aggressor(s) may be as great or greater than the harm threatened. A case in which self-defense is used lethally against multiple aggressors can be made to fit the necessity formula only if (a) the fact that those killed were aggressors is assumed ipso facto to make their actions the greater evil, or (b) recognition of self-defense as justification is said to have second-order benefits that enter in the calculus, such as the effect of discouraging other aggressors, fostering respect for law, and enhancing general security and personal autonomy. Obviously the same issues arise when persons acting under cover of legal authority appear to carry out greater harm than that threatened.

Duress. Persons who act out of necessity and persons who act under duress do so in the face of threatened harm. Both the theory of necessity and the theory of duress draw attention to the pressure of exigent and extraordinary situations, pressure that prompts a harm-causing response. But necessity focuses on the anticipated consequences of the harming action, the concrete alternatives or choice facing the actor. Duress, on the other hand, focuses on the way in which the choice was made and the extent to which it can or cannot be said to reflect the free will of the actor.

Thus, acting out of necessity, an actor makes the optimal choice, aware that doing so entails a technical violation of the law. An actor under duress also chooses, but in a way that demands qualification. The pressure of the situation is said to be such that a person of reasonable firmness would not be able to resist doing harm. Such harmful actions, done as capitulation to threats, are not to be taken as an expression of the actor's will.

Necessity is generally held to be a justification, while duress is considered an excuse. A person acting under necessity chooses to act in a way that the law seems to approve and encourage, presumably for utilitarian reasons. The person who acts under duress, on the other hand, acts in a way that is generally regrettable and deserves to be discouraged, but the special circumstances make conviction inappropriate and unfair. Unlike necessity, excuses such as duress, intoxication, and provocation (which may mitigate rather than exculpate) refer to situations in which harmful choices may not be representative of the actor's character or desires.

The distinction between the justification of necessity and the excuse of duress has implications for accomplice liability. One who aids a principal acting under duress may be criminally liable (unless the accomplice was also under duress). Excuses are personal. By contrast, those who aid necessary conduct act with impunity. No legal blame can attach to those who help bring about justified acts.

Of course, some situations fall under both defenses. An actor may choose the lesser evil while also acting under duress. Consider, for example, a defendant forced to carry out a nonviolent act of theft by persons who have kidnapped members of her family and threatened to kill them. In general, duress rather than necessity would be the preferred defense in such cases.

Several commentators have criticized the distinction between necessity and duress as artificial and unconvincing. George Fletcher notes that the distinction is rarely made in foreign legal systems. He and others (Brudner, for example) point out that the utilitarian determination at the core of the necessity defense is disturbingly unclear. In cases of stealing bread to avoid starvation, for example, is the weighing to be done narrowly, balancing the threat of death for the starving offender against the financial interests of the baker? Or is the effect on general compliance for law and respect for law of such precedents also part of the account? Critics such as Colvin and Parry conclude if we cannot know what counts in the weighing, we cannot perform the calculus. They argue that what is really at issue is our moral perspective on the actor and a sense of his psychological characteristics as manifested in the act—and that this empathetic adaptation of the law lies at the heart of necessity and duress alike, erasing the difference between them.