Necessity

Controlling force; irre sislible compulsion; a power or impulse se great that it admits no choice of conduct. When it is said that an act is done “under necessity,” if may be, in iaw, either of three kinds of necessity: (1) The necessity of preserving one’s own life, which will excuse a homicide; (2) the necessity of obedience, as to the laws, or the obedience of one not sué Juris to his superior; (3) the necessity caused by the act of God or a stranger. See Jacob; Mozley & Whitley. A constraint upon the will whereby a person is urged to do that which his judgmeut disapproves, and which, it is to be presumed, his will (if left to itself) would reject. A man, therefore, is excused for thoss actions which are done through unevoidable force and compulsion.

Wharton.