A Procedural Rationale for the Necessity Defense

The lion comes daily to the library and is beloved by the patrons and by the head librarian, Miss Merriweather. The library has many rules, but only one of them is of particular importance to the lion: no roaring allowed. The penalty for violation, as the lion well knows, is nothing less than excommunication. When Miss Merriweather falls and breaks her arm while reaching to a high shelf, the lion finds that the only way he can get help is to roar. The embittered assistant librarian, Mr. McBee, enforces the rule and the lion has no choice but to leave the library. At this point, the child who is listening to the illustrated book Library Lion, recoils in horror. How can it be, thinks the child, that someone could be punished for doing what was clearly the best thing to do in the circumstances? The child’s horror is reflected in the criminal law in the affirmative defense of necessity, also called the lesser evils defense. A defendant who uses it says that, given the peculiar circumstances he faced, the act for which he is charged with a crime was better, all told, than any alternative. Some patrons are disturbed, to be sure, but Miss Merriweather gets the medical attention she badly needs. Alternatively, to give an example of the sort that actually appears in the law, the defendant trespasses in order to prevent a fire from spreading, arguing that the trespass is much less bad than the fire damage that was thereby prevented. The affirmative defenses, such as infancy, insanity, public duty, self-defense, and necessity, are ordinarily divided into excuses and justifications. The excuses are typically glossed as instances in which the defendant was not fully responsible for