Legal Definitions - necessity

In law, necessity refers to a situation where a person commits an act that would normally be considered illegal or wrongful, but does so out of an urgent need to prevent a greater harm from occurring. It can serve as a defense in criminal cases or as a privilege that limits liability in civil (torts) cases. The core idea is that, in extreme circumstances, choosing the "lesser evil" is justifiable.

Necessity in Criminal Law

In criminal law, necessity is a defense that argues a person should not be held criminally responsible for an illegal act because they were forced to commit it by an emergency situation they did not create. The act committed must be less harmful than the harm that would have occurred if the person had not acted. This is sometimes called the "choice of evils" defense.

• Example 1: Emergency Medical Transport
  A parent is driving their child to the hospital because the child is having a severe, life-threatening allergic reaction. To get to the hospital in time, the parent exceeds the speed limit and runs a red light, actions that are typically illegal.

  How it illustrates necessity: The parent's actions (speeding, running a red light) are illegal, but they were taken to prevent a much greater harm—the potential death or severe injury of their child. The emergency was not created by the parent, and their actions were necessary to address it.

• Example 2: Protecting Property from Imminent Danger
  During a sudden, severe flood, a homeowner notices that a large, loose piece of debris is about to smash through their neighbor's window, potentially causing extensive damage to the house and its contents. The homeowner quickly breaks a small pane of glass in their neighbor's door to gain entry and secure the debris, preventing much greater destruction.

  How it illustrates necessity: Breaking the neighbor's glass is technically property damage. However, it was done to prevent significantly greater damage to the neighbor's property from the flood. The homeowner acted in an emergency not of their making, choosing the lesser harm.

Necessity in Torts (Civil Law)

In tort law, necessity acts as a privilege that can relieve a person from liability for harming another's property if they had no reasonable alternative and acted to protect life, health, or a greater public interest. This concept is further divided into private necessity and public necessity.

Private Necessity

Private necessity is a privilege that allows a person to damage or interfere with another's property to protect their own personal interests (e.g., their own life, health, or property) from a serious threat. While the person is excused from trespass, they are generally still liable for any actual damage caused to the property.

• Example 1: Seeking Shelter During a Storm
  A boater is caught in an unexpected, violent storm on a lake. To prevent their boat from capsizing and to save their own life, they moor their boat to a private dock belonging to someone else without permission, causing minor scrapes and damage to the dock's paint.

  How it illustrates private necessity: The boater acted out of necessity to protect their life and property from the storm. They had a privilege to use the private dock to prevent a greater harm. However, because it was for their private interest, they would still be responsible for compensating the dock owner for the damage caused.

• Example 2: Diverting a Threat to One's Property
  During a wildfire, a rancher, seeing that the fire is rapidly approaching their home and livestock, uses a bulldozer to create a firebreak by clearing a strip of land on an adjacent, unoccupied private property. This action destroys some of the neighbor's trees and vegetation.

  How it illustrates private necessity: The rancher's actions were necessary to protect their own substantial property and livelihood from imminent destruction. While they had a privilege to enter and alter the neighbor's land to prevent this greater harm, they would likely be required to pay for the damage caused to the neighbor's property.

Public Necessity

Public necessity is a privilege that allows a person, typically a government official or someone acting on behalf of the community, to damage or destroy private property to protect the public interest from a widespread, imminent danger. In cases of public necessity, the person causing the damage is completely excused from liability and does not have to compensate the property owner.

• Example 1: Preventing the Spread of Disease
  During a severe outbreak of a highly contagious animal disease, public health officials order the humane destruction of all livestock on a particular farm to prevent the disease from spreading to other farms and endangering the entire regional agricultural industry.

  How it illustrates public necessity: The destruction of private property (the livestock) was carried out to protect the broader public interest—preventing a widespread epidemic that would have devastating economic and health consequences for the community. The officials would not be liable for the loss of the livestock.

• Example 2: Containing a Hazardous Spill
  After a train derailment causes a chemical spill near a residential area, emergency response teams intentionally demolish a vacant commercial building to create a containment barrier and prevent the toxic chemicals from reaching homes and contaminating the public water supply.

  How it illustrates public necessity: The demolition of the building, though private property, was necessary to protect the health and safety of a large number of people and the environment from a severe public hazard. The emergency responders would not be held liable for the destruction of the building.