Justification: Necessity

The prohibitions of criminal law apply in "normal" situations. The various criminal defenses delineate situations that are, in relevant ways, exceptional. Persons may not kill, but the defense of self-defense makes clear that they may do so in the exceptional circumstance of being threatened with deadly force. Similarly, one may commit harm with legal impunity if under the influence of a serious, credible, and imminent physical threat, that is, if one acts under duress. The defense of necessity alludes to exceptional circumstances in which compliance with the law is likely to involve greater harm to persons or property than would violating it.

For example, running a stop light may be justified when the passenger in one's car has a medical emergency for which every second counts. A hiker lost in the woods in a sudden ice storm or impending avalanche may seek shelter and trespass in an empty house to save her life. Or an individual fighting a forest fire may have to seize and destroy private property to create a firebreak and prevent still greater damage. In each of these situations, the defense of necessity is available to justify harmful actions when the actor deliberately chooses the lesser evil. The notion of necessity does not, as the term might imply, refer to the absence of choice, the implication that one's actions were necessitated and not freely willed. Rather it implies the actor was appropriately concerned to minimize harm, and in that sense engaged in the kind of conduct that law may reasonably encourage.

Certain limits follow from this understanding of the defense of necessity. The harm-causing violation of a legal prohibition must be the least harmful alternative. It is not available if the actor is aware of other options that would further minimize the breach. By the same token, the actor is not fully exculpated if he creates the situation of choice-of-evils out of negligence. The driver who knowingly uses a car with defective brakes will remain criminally liable for his reckless damage when he swerves to avoid a pedestrian and runs into a shop window. On the other hand, the actor who chooses the apparent lesser evil out of a reasonable good faith misunderstanding may nonetheless claim necessity. He may, for example, interrupt two actors rehearsing the assassination scene from Julius Caesar by assaulting the actor playing Brutus in the false belief that the threatened stabbing is a genuine attack.

Many recent cases have tested the limits of the necessity defense. So-called pro-life abortion protestors have invoked it as a defense for trespass on the private grounds of abortion clinics and even for killing doctors and nurses (Wichita v. Tilson, 855 P2d. 911 (1993)). Necessity has been claimed in euthanasia cases; defendants have argued that the perpetuation of suffering in the face of inevitable death is the greater evil (for example, Gilbert v. State, 487 So.2d. 1185 (1986)). Necessity is also arguably relevant as a defense for persons accused of dispensing such prohibited drugs as marijuana for medical purposes (State v. Tate, 505 A2d. 941 (1986)). And, for at least four decades, civil disobedients have argued that their violations of law are justified by their cause, whether it is nuclear disarmament, an "immoral" war, or the preservation of the environment.

In general, courts refuse to entertain the necessity defense when a political or moral controversy underlies the assessment of harms or when the authors of the relevant criminal prohibitions can be said to have anticipated and rejected the claim at issue. Clearly a government that has committed itself to a military campaign has made the political decision that failing to act would be worse than acting. Protestors cannot find legal cover in arguing that war is the greater evil. But courts struggle with the application of necessity to euthanasia and drug cases. Were homicide statutes and drug statutes drafted in anticipation of such cases? If not, the necessity defense remains available, if not always persuasive in particular cases.