Key Takeaways

  • The definition of necessity in law refers to situations where unlawful conduct may be excused or justified because it was the only reasonable option to prevent greater harm.
  • Necessity can serve as a defense in criminal law (the “necessity defense”), excusing acts like trespassing or minor lawbreaking when done to preserve life, prevent injury, or stop serious harm.
  • Courts require strict conditions: the threat must be imminent, the harm avoided greater than the harm caused, and the defendant must not have contributed to the situation.
  • Necessity is distinct from duress, though both involve compulsion. Duress involves coercion by another person, while necessity arises from external circumstances or natural forces.
  • The doctrine extends beyond criminal law into property law (e.g., easements of necessity when land access is blocked) and tort law (limited privileges to trespass to prevent damage).
  • Some courts reject necessity defenses in specific contexts (e.g., civil disobedience or prison escape cases) where public policy concerns outweigh the justification.

In general, whatever makes the contrary of a thing impossible, whatever may be the cause of such impossibilities.

Necessity and the Law

Whatever is done through necessity, is done without any intention, and as the act is done without will, and is compulsory, the agent is not legally responsible. Hence the maxim, necessity has no law; indeed necessity is itself a law which cannot be avoided nor infringed.

It follows, then, that the acts of a man in violation of law., or to the injury of another, may be justified by necessity, because the actor has no will to do or not to do the thing, he is a mere tool; but, it is conceived, this necessity must be absolute and irresistible, in fact, or so presumed in point of law.

The Necessity Defense in Criminal Law

In criminal law, necessity is most often raised as a defense. The defendant argues that they committed a technically unlawful act to avoid a greater harm, and therefore should not be held criminally liable. Courts usually require that several elements be satisfied for the defense to apply:

  • The defendant faced a clear and imminent danger.
  • The unlawful act was necessary to prevent that danger.
  • There was no legal alternative to breaking the law.
  • The harm avoided was greater than the harm caused.
  • The defendant did not substantially contribute to the emergency situation.

For example, a driver who speeds to rush an injured person to the hospital may invoke necessity. Similarly, breaking into a cabin during a snowstorm to avoid freezing to death can be justified under this defense.

Cases Which Are Justified by Necessity

The cases which are justified by necessity, may be classed as follows: For the preservation of life; as if two persons are on the same plank, and one must perish, the survivor is justified in having thrown off the other, who was thereby drowned.

Obedience by a person subject to the power of another; for example, if a wife should commit a larceny with her husband, in this case the law presumes she acted by coercion of her husband, and, being compelled, by necessity, she is justifiable. Those cases which arise from the act of God, or inevitable accident, or from the act of man, as public enemies.

There is another species of necessity. The actor in these cases is not compelled to do the act whether he will or not, but he has no choice left but to do the act which may be injurious to another, or to lose the total use of his property. For example, when a man's lands are surrounded by those of others, so that he cannot enjoy them without trespassing on his neighbors. The way which is thus obtained, is called a way of necessity.

Distinction Between Necessity and Duress

Although related, necessity and duress are distinct legal doctrines. Necessity arises from natural or circumstantial pressures, such as a fire, storm, or medical emergency, that compel unlawful action to prevent harm. Duress, on the other hand, results from coercion by another person—for instance, being forced at gunpoint to commit a crime. Courts often emphasize this difference because necessity is based on a balancing of harms, while duress focuses on lack of free will due to threats from another.

Necessity in Property and Tort Law

Beyond criminal law, necessity plays a role in property and tort doctrines. In property law, an easement of necessity may be recognized when a landowner’s parcel is completely surrounded by others’ land, leaving no access route. The law grants a “way of necessity” to ensure the property can be used.

In tort law, the defense of necessity can justify certain trespasses. For example, a person may enter another’s land to prevent greater harm, such as extinguishing a spreading fire. However, while the trespass may be excused, the individual might still owe compensation for any actual damage caused. This reflects the balance between protecting property rights and acknowledging unavoidable emergencies.

Frequently Asked Questions

1. What is the legal definition of necessity?

Necessity refers to circumstances where a person commits an otherwise unlawful act to avoid a greater harm, often serving as a legal defense.

2. How does the necessity defense work in criminal law?

The defense applies when the defendant faced imminent danger, had no legal alternative, and acted to prevent greater harm than the act caused.

3. What is the difference between necessity and duress?

Necessity arises from external circumstances, like emergencies, while duress involves coercion or threats by another person.

4. Can necessity justify trespassing?

Yes. For instance, entering private property to avoid serious injury or death may be excused, though damages might still be owed.

5. Do all courts recognize necessity as a defense?

Not always. Some courts limit or reject the defense, particularly in cases of civil disobedience, prison escapes, or where public policy outweighs individual circumstances.

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