term:

Necessity

necessity n

pl: -ties
1 a : the presence or pressure of circumstances that justify or compel a certain course of action
;esp
: a need to respond or react to a dangerous situation by committing a criminal act
b : an affirmative defense originating in common law that the defendant had to commit a criminal act because of the pressure of a situation that threatened a harm greater than that resulting from the act see also choice of evils defense at defense compare duress, undue influence
2 : something that is necessary esp. to subsistence [obligated to provide the necessities of food, clothing, and shelter]

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.