A legal defense in which the defendant admits to committing the act in question but claims it was necessary in order to avoid some greater evil

The Justification Defense:

Justification defenses include Necessity, Defense of others, Defense of property, Law Enforcement Defense, Consent. Excuse defenses include Duress, Entrapment, Ignorance of the Law, Diminished Capacity Defense, Provocation, Insanity Defense, and Infancy Defense.