Justification: Necessity

The utilitarian bases of the necessity defense are problematic if it is seen as a guide for action, a rule permitting actors to choose the lesser evil even when doing so involves a violation of law. Given the uncertain nature of the determination itself, one may question whether actors will generally be able to choose the lesser evil correctly and whether knowledge of the availability of the defense will lead to its abuse. These difficulties are mooted if one sees the necessity defense, like other defenses, not as a rule of conduct directed at actors but as a rule for courts in assessing culpability retrospectively. From this standpoint, the defense of necessity seems to rest on the principle that it is unfair to punish those who violate the law with the motive of minimizing harm and in the reasonable and sincere belief that they are doing so. Whether or not the defense may be abused, elimination of it would make the law unfair and breed disrespect of it. The cost to society of such disillusionment with law is arguably greater than the risk of abuse of the necessity defense.

To see necessity and other defenses as second-order rules governing the administration of laws rather than as first-order rules directed at actors has an important implication. The first-order prohibitions of criminal law address on intent (or mens rea generally); motive is said to be irrelevant. The defenses, by contrast, bridge intent and motive. When a defendant uses the necessity defense, she concedes that she caused harm intentionally but argues that her motive was to avoid greater harm by doing so. The moral imperative of fairness that seems to underlie necessity forces us to take motive into account.

The extent to which determinations of greater and lesser evil involve more than simple calculi and are embedded in moral assumptions is clear in many examples. Cases in which taking life is arguably the lesser evil almost always go beyond counting lives. In considering cases about persons jettisoned from overburdened lifeboats or persons cannibalized to save the ravaged survivors of shipwreck, courts have asked whether the selection of the victim was fair, whether the survivor owed a duty of care to the victim, and whether the victim acceded to his fate (see The Queen v. Dudley & Stevens, 14 Q.B.D. 273 (1884) for a historical treatment of this issue). There is no unanimity about justified killing under necessity even when these complications are absent.

Suppose a healthy autonomous individual were the uniquely compatible donor whose vital body parts, if transplanted efficiently, would save eight patients who otherwise face imminent death. It is clear that kidnapping and sacrificing the donor cannot be defended on grounds of necessity. One moral intuition is that nothing can justify compromising so decisively the autonomy and life of the donor when, unlike the joint shipwreck victims, he has not already been compromised by natural circumstances. It is clear, from this and other examples, that the notion of greater and lesser evils is both indispensable to an understanding of fairness in applying criminal prohibitions and endlessly problematic.