Necessity Defense in Wisconsin

Pressure of natural physical forces which causes the actor reasonably to believe that his or her act is the only means of preventing imminent public disaster, or imminent death or great bodily harm to the actor or another and which causes him or her so to act, is a defense to a prosecution for any crime based on that act, except that if the prosecution is for first-degree intentional homicide, the degree of the crime is reduced to 2nd-degree intentional homicide. 

The defense of necessity is based on the policy that there are times when a higher value is promoted by violating a less significant value; that the greater good for society can, in some instances, only be accomplished by violating the literal language of the criminal law. The matter is often expressed in terms of choice of evils: When the pressure of circumstances presents one with a choice of evils, the law prefers that he avoid the greater evil by bringing about the lesser evil.

The ability justifiably to choose between evils is available in Wisconsin only if the person asserting the defense acted under "pressure of natural physical forces."  Examples of these forces are storms, fires, and privations. Thus, a person lost in a storm who breaks into an isolated house in order to take refuge is justified in so doing by the doctrine of necessity. A person who, seeking to stop the spread of a fire, razes a building in order to save a town is similarly justified. A third example is that of a person who throws property from an overcrowded boat in order to prevent it from sinking.  In a past Wisconsin case, a man tried to block tranportation of spent nuclear fuels and was charged with disorderly conduct.  The Courts determined that he was not entitled to the defense of necessity because the transportatin of fuels can be controlled unlike storms, fires, and shipwrecks.