Donald, charged by a raging bull, hits it with Victoria's Ming vase, destroying the vase but diverting the bull. Is Donald guilty of intentional damage to Victoria's property? Martina tells Ken that unless Ken steals Joan's lawn mower, Martina will kill him. If Ken does so, is he guilty of larceny? Suppose the threat is not to kill Ken but to destroy his Mercedes. What then? Finally, Ebenezer sees Marley coming at him with what appears to Ebenezer to be a machine gun. May Ebenezer pull out a pistol and shoot Marley, or must he wait until Marley himself actually shoots?
In each of these situations, the defendant is faced with a situation in which a decision must be made instantly. Rather than labeling all three such acts as “emergency decisions” and treating them similarly, the common law created separate doctrines that, while similar, have been treated differently with somewhat different rules. Thus, Donald would have to argue that he acted in “necessity” (choosing the lesser of two evils). Ken, in either of the examples, would have to argue “duress.” Finally, Ebenezer would claim neither of these defenses but “self-defense.”