A more thorough explanation:

Definition: Necessity is a defense used in criminal law when a person acts in an emergency that they did not create and commits a harm that is less severe than the harm that would have occurred if they did not act. It can also be a privilege in tort law that may relieve a person from liability for trespass or conversion if they harm another's property in an effort to protect life or health.

• A mountain climber lost in a blizzard can use necessity as a defense to theft of food and blankets from another's cabin.
• If a person breaks into a car to rescue a child who is locked inside on a hot day, they may be able to use necessity as a defense in court.
• If a firefighter breaks down a door to put out a fire and damages the property, they may be able to use public necessity as a defense in court.

These examples illustrate how necessity can be used as a defense or privilege in different situations. In each case, the person acted to prevent a greater harm from occurring and the harm they caused was less severe than the harm that would have occurred if they did not act. Necessity is not an excuse for intentional harm, but it can be a defense when a person is faced with a difficult situation and has no other choice but to act.