parent nodes: common law | Criminal Law | justification | theft
necessity
Doctrine
(1) Conduct that the actor believes to be necessary to avoid a harm or evil to himself or to another is justifiable, provided that:
(a) the harm or evil sought to be avoided by such conduct is greater than that sought to be prevented by the law defining the offense charged; and
(b) neither the Code nor other law defining the offense provides exceptions or defenses dealing with the specific situation involved; and
(c) a legislative purpose to exclude the justification claimed does not otherwise plainly appear.
(2) When the actor was reckless or negligent in bringing about the situation requiring a choice of harms or evils or in appraising the necessity for his conduct, the justification afforded by this Section is unavailable in a prosecution for any offense for which recklessness or negligence, as the case may be, suffices to establish culpability.
The easiest case is using another's property without intention to damage in order to protect one's own property; the situation is more difficult where one person purposefully damages another's property in order to protect his own.
Note that for example a person under necessity trying to moor at a dock probably has a right to use force against a dockowner using force to keep the person off the dock; the dockowner would actually be guilty of a crime, having forfeited the justification of self-defense on his part. The situation of necessity effectively reverses the distribution of property rules between the person under necessity and the owner of damaged property.
When administrative remedies are available, you have to exhaust possible administrative remedies before resorting to self-help under necessity. Cf. [People v Unger] (escaping inmate threatened with death if he reported his abuse to guards).
The success of a neccessity defense based off a political stance is more likely to succeed where (1) the less the form of protest used has been used before (2) the political system is less open to public participation and (3) the target of protest is more specific.
Cases
R v Dudley and Stephens (no necessity where two sailors killed and ate third sailor in order to survive)
[People v Unger] (escape from minimum security prison justified by death threats and sexual abuse)
State v Warshow (no necessity defense to trespassers trying to block allegedly unsafe power plant from operating)