Necessity as a Criminal Defense

Necessity as a Criminal Defense

Criminal law generally tells people what they must not do. Do not steal. Do not trespass. Do not damage property. Do not drive recklessly. Do not enter certain places without authorization.

But what happens when obeying the law would expose someone to a much greater danger?

Imagine a driver stranded in a remote area during a severe winter storm. The driver’s vehicle has broken down, temperatures are falling rapidly, and there is no shelter nearby. The driver breaks into an unoccupied cabin to escape the cold.

Ordinarily, breaking into another person’s property may constitute a criminal offense. But the driver may argue that the circumstances made the violation necessary to avoid a more serious harm.

This is the basic idea behind the necessity defense.

Necessity is a justification defense that recognizes that, under certain circumstances, violating one criminal prohibition may be legally justified when doing so is necessary to prevent a significantly greater harm.

Cornell Legal Information Institute — Necessity Defense

The doctrine is sometimes associated with the phrase “choice of evils.” The defendant essentially argues that the law should not impose criminal punishment for choosing the lesser harm when confronted with an immediate and unavoidable greater danger.

But necessity is a carefully limited defense. A person cannot simply decide that breaking the law would produce a preferable outcome and then call the conduct “necessary.”

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What Is Necessity?

Necessity is a criminal defense based on the idea that otherwise criminal conduct may be justified when it was reasonably necessary to prevent a greater harm under the circumstances.

The classic structure is:

The defendant violated the law in order to avoid a more serious harm.

For example:

A person sees a small child trapped inside a locked vehicle on an extremely hot day. The child appears to be suffering and immediate intervention is necessary. The person breaks the vehicle’s window to rescue the child.

Breaking the window may ordinarily constitute criminal damage to property.

But if breaking the window was reasonably necessary to prevent serious injury or death, necessity may potentially provide a justification.

The important point is that the defendant is not arguing:

“I wanted to break the window.”

The argument is:

“Breaking the window was necessary to prevent a substantially greater harm.”

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Necessity Is a Justification Defense

Necessity is generally classified as a justification defense.

That means the defendant is arguing that the conduct was legally justified by the circumstances.

This is different from an excuse defense.

An excuse generally accepts that the conduct was wrongful but argues that the particular defendant should not be held responsible.

Necessity instead says, in substance:

Under these circumstances, the otherwise prohibited conduct was justified because it prevented a greater harm.

That distinction is important.

The law is not necessarily forgiving the defendant.

It is recognizing that the defendant’s conduct may have been the legally preferable choice in an emergency.

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The Basic Principle: Choosing the Lesser Harm

The philosophical foundation of necessity is often described as the lesser-evil principle.

Suppose a person faces two possible outcomes:

• Outcome A: violate a criminal law and prevent serious injury.
• Outcome B: obey the law but allow serious injury to occur.

Necessity asks whether the law should regard Outcome A as justified.

For example, imagine that a person is driving a car when a passenger suddenly suffers a life-threatening medical emergency.

The driver exceeds the speed limit to reach a hospital as quickly as possible.

Ordinarily, speeding violates the law.

But if the circumstances genuinely required immediate transportation and the driver’s conduct was reasonably connected to preventing serious harm, necessity may become relevant depending on the jurisdiction and offense.

The underlying reasoning is:

Sometimes the law’s prohibition must yield to a more fundamental interest.

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The Elements of Necessity

The precise requirements differ among jurisdictions, but necessity generally involves several important considerations.

1. There must be a significant or imminent harm

The defendant generally must have faced a sufficiently serious danger.

A trivial inconvenience will ordinarily not justify violating criminal law.

For example:

“I trespassed because I was late for work.”

is fundamentally different from:

“I entered the building because I was escaping an immediate threat of serious physical harm.”

The seriousness of the threatened harm is therefore central.

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2. The danger must generally be imminent

Necessity usually concerns emergencies rather than distant or speculative dangers.

Consider:

“If I do not break this window right now, the person inside may die.”

That presents a potential necessity situation.

Compare:

“There might be a serious problem sometime next month.”

That generally does not create the same justification.

The doctrine is designed primarily for circumstances in which the defendant must make a decision under immediate pressure.

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3. The defendant must reasonably believe that the conduct was necessary

The defendant’s perception of the circumstances is important.

Suppose someone breaks into a house because they believe a person inside is suffering a medical emergency.

If there was no emergency and the defendant’s belief was unreasonable, the necessity defense may fail.

The law therefore commonly examines whether the defendant’s belief concerning the danger and the need for action was reasonable.

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4. There must generally be no adequate lawful alternative

Necessity becomes much harder to establish when the defendant could reasonably have avoided the harm without violating the law.

Suppose someone breaks into a building because they are cold.

If a heated public shelter is immediately available nearby, the argument for necessity may be considerably weaker.

The defense generally requires a genuine conflict between:

• following the law; and
• preventing the threatened harm.

If the defendant could easily prevent the harm through lawful means, breaking the law may not be considered necessary.

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5. The harm avoided must generally outweigh the harm caused

This is the heart of the lesser-evil analysis.

Suppose someone destroys an abandoned shed to create a firebreak during an approaching wildfire.

The defendant has caused property damage.

But if destroying the shed prevents the fire from spreading into a densely populated area, the harm prevented may be substantially greater.

The comparison is not necessarily precise mathematics.

Courts may instead ask whether the defendant’s conduct was reasonably related to avoiding a substantially greater danger.

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6. The defendant must not have wrongfully created the emergency

A major limitation on necessity concerns the defendant’s own responsibility for creating the dangerous situation.

Suppose a person deliberately starts a dangerous fire and then destroys someone else’s property to escape the consequences.

The person’s ability to invoke necessity may be severely limited.

The law is generally reluctant to allow someone to manufacture an emergency and then claim that the emergency justified subsequent criminal conduct.

This principle prevents necessity from becoming a mechanism for escaping responsibility for dangers the defendant deliberately created.

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Necessity and Imminence

Imminence deserves particular attention.

The closer the danger is to immediate harm, the stronger the traditional necessity argument tends to be.

Imagine a person trapped on a mountain during a sudden blizzard.

The person breaks into an empty cabin to survive the night.

The danger is immediate.

Now imagine someone believes that severe weather might arrive several days later and breaks into the cabin in advance.

The second case presents a much weaker necessity argument because the defendant may have had other lawful alternatives.

Necessity is fundamentally an emergency doctrine.

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Necessity and Proportionality

The defendant’s response must generally be connected to the danger being avoided.

A person cannot ordinarily cause catastrophic harm to avoid a minor inconvenience.

For example:

Breaking a window to rescue a trapped child.

may potentially be justified.

But:

Burning down an entire building because the defendant wants to rescue a bicycle.

would present a radically different proportionality problem.

The response must therefore be reasonably related to the seriousness of the threatened harm.

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Necessity vs. Duress

Necessity and duress are often confused because both involve circumstances that pressure a defendant into committing a criminal act.

But they are conceptually different.

Necessity

The defendant commits the offense because of a threat from circumstances or conditions.

For example:

A person damages property to escape a deadly natural disaster.

Duress

The defendant commits the offense because of a threat from another person.

For example:

An armed person threatens to kill the defendant unless the defendant helps commit a robbery.

Thus:

Necessity generally concerns circumstances.

Duress generally concerns coercion by another person.

The distinction can become complicated in particular cases, but it is fundamental to understanding the two defenses.

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Necessity vs. Self-Defense

Necessity also differs from self-defense.

Self-defense generally involves the use of force to protect oneself from unlawful force by another person.

Necessity is broader and concerns conduct taken to avoid a greater harm.

For example:

A person is attacked by someone carrying a knife and uses force to stop the attacker.

That is primarily a self-defense situation.

A person is trapped in a burning building and breaks through a wall to escape.

That is more naturally analyzed under necessity.

Both doctrines are concerned with emergencies, but the source and nature of the danger differ.

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Necessity vs. Defense of Property

Necessity can also overlap with defense of property.

Suppose a wildfire is approaching rapidly and a person destroys part of a fence to create a path for evacuation.

The person has interfered with property.

But the primary justification may be necessity because the conduct was undertaken to prevent a greater danger.

By contrast, if the person pushes a thief away from the fence to stop the thief from stealing it, the more natural analysis is defense of property.

The distinction depends on why the defendant acted and what danger the defendant was trying to prevent.

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Necessity and Natural Disasters

Natural disasters provide some of the clearest examples of necessity.

Consider:

• hurricanes;
• floods;
• wildfires;
• earthquakes;
• blizzards;
• tornadoes;
• landslides; or
• other extreme emergencies.

During such events, ordinary legal rules may collide with urgent survival needs.

A person may need to:

• enter private property;
• take emergency supplies;
• destroy property to prevent a greater disaster;
• operate a vehicle in an otherwise prohibited manner; or
• take other extraordinary measures.

Necessity recognizes that emergency conditions can sometimes fundamentally alter the legal significance of conduct.

But the existence of a disaster does not automatically create immunity from criminal law.

The defendant must still satisfy the applicable legal requirements.

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Necessity and Medical Emergencies

Medical emergencies can also create necessity issues.

Suppose someone discovers an unconscious person who appears to require immediate medical attention.

The person breaks into a locked building to obtain an emergency medical device.

Ordinarily, breaking into the building could constitute a crime.

But if there was no reasonable alternative and the action was necessary to prevent imminent serious harm, necessity may potentially apply.

The urgency of the medical situation, the availability of alternatives, and the reasonableness of the response would all matter.

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Necessity and Property Offenses

Necessity frequently arises hypothetically in connection with property crimes.

Imagine a person stranded in freezing conditions who takes food from an abandoned store because there is no other available means of survival.

The person has technically interfered with another’s property.

But the legal system may ask whether the circumstances created a genuine necessity.

The key question is not simply:

“Was something taken?”

It is:

“Was taking it reasonably necessary to prevent a substantially greater harm?”

The existence of the property offense does not automatically answer the justification question.

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Necessity and Driving Offenses

Driving emergencies provide another useful example.

Suppose a passenger suffers a severe medical emergency and the driver speeds toward the nearest hospital.

The driver technically violates traffic laws.

But the driver may argue that the emergency made compliance with the ordinary speed limit impracticable or that the conduct was necessary to prevent serious harm.

Whether such a defense is available depends heavily on the jurisdiction and the specific statute involved.

Some offenses may contain their own emergency exceptions or statutory defenses.

Therefore, necessity should not automatically be assumed whenever someone violates a traffic law during an emergency.

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Necessity and Public Policy

Necessity raises a difficult policy question:

Should individuals be permitted to violate laws whenever they believe doing so will produce a better result?

If the answer were simply yes, criminal law would become unpredictable.

Every defendant could potentially argue:

“I broke the law because I thought the outcome would be better.”

The necessity defense therefore requires boundaries.

Courts generally examine the seriousness of the danger, the immediacy of the threat, the availability of lawful alternatives, the proportionality of the response, and other jurisdiction-specific requirements.

The doctrine is therefore not a general permission to disregard criminal law whenever the defendant believes that doing so is useful.

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The “Choice of Evils”

Necessity is sometimes described as the choice of evils defense.

The phrase captures the basic dilemma.

The defendant is confronted with competing harms and must choose.

For example:

Either damage the property or allow a person to suffer potentially fatal harm.

The defendant chooses property damage.

Necessity asks whether that choice was legally justified.

This reveals something important about criminal law.

Criminal law is not simply a list of isolated commands. It is also a system for resolving conflicts between competing social interests.

In an emergency, two legal interests may collide.

The law may prohibit damaging property, but it also strongly values human life.

Necessity provides a mechanism for evaluating that conflict.

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Necessity and the Law of Emergency

Emergency situations expose the difference between formal legal rules and substantive justice.

Under ordinary circumstances, a person should respect another person’s property.

Under extraordinary circumstances, however, strict adherence to that rule may produce a far worse outcome.

Imagine a person trapped in a burning building who must break through a locked door to escape.

The law could theoretically focus exclusively on the property damage.

But doing so would ignore the fundamental purpose of criminal law.

Necessity allows the legal system to recognize that circumstances matter.

The law is not abandoning rules.

It is determining whether the rule should produce criminal liability in an extraordinary situation.

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Necessity and Mistake

A defendant may sometimes be mistaken about whether a necessity actually existed.

Suppose a person believes a flood is about to destroy a building and breaks into another property to escape.

It later turns out that the flood never reached the area.

The legal analysis may depend on whether the defendant’s belief was reasonable given the information available at the time.

This is another reason why courts must avoid evaluating emergency decisions entirely through hindsight.

The relevant question may be what a reasonable person in the defendant’s position could have perceived at the time.

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The Importance of Alternatives

The availability of alternatives is one of the most important practical questions.

Consider a person who breaks into a locked pharmacy to obtain medication during an emergency.

If the pharmacy is the only immediately available source and the person faces a genuine medical crisis, necessity may be plausible.

But if an open pharmacy is located next door, the necessity argument becomes much weaker.

The law generally expects a person to use lawful alternatives when those alternatives are reasonably available.

Necessity is strongest when the defendant truly faces a forced choice.

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Necessity and Personal Benefit

Another important consideration is whether the defendant’s conduct was genuinely motivated by avoiding the threatened harm.

Suppose a person claims:

“I took the vehicle because I needed it to escape a wildfire.”

But evidence shows that the person actually intended to steal the vehicle for personal use and simply later invoked the wildfire as an explanation.

The credibility of the necessity claim becomes critical.

Necessity is not established merely by attaching an emergency explanation to otherwise criminal conduct.

The circumstances, the defendant’s actions, and the surrounding evidence all matter.

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A Practical Example

Consider this scenario.

A family is traveling through a remote area during an unexpected blizzard.

Their vehicle becomes disabled.

Temperatures fall rapidly, and the family has no working communication device.

Several kilometers away, they see an unoccupied cabin.

The door is locked.

One member of the family breaks the door to enter the cabin and obtain shelter.

The person may face criminal liability for damaging property or unlawful entry.

But a necessity defense could potentially arise.

The analysis would ask:

1. Was there an imminent threat to human life or serious bodily injury?
2. Did the defendant reasonably believe the threat existed?
3. Was entering the cabin necessary to avoid the danger?
4. Were there reasonable lawful alternatives?
5. Was the property damage proportionate to the danger?
6. Did the defendant use the property only as necessary?
7. Did the defendant leave or notify the owner when the emergency ended?
8. Did the defendant create the emergency through wrongful conduct?

Now change the facts.

The family has a working vehicle, a functioning phone, and a hotel five kilometers away.

They nevertheless break into the cabin because they prefer it to the hotel.

The necessity argument becomes substantially weaker because lawful alternatives exist.

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When Necessity Does Not Apply

Necessity generally cannot be treated as a universal excuse for criminal conduct.

The defense may fail when:

The harm was not imminent

A speculative future danger is generally insufficient.

A lawful alternative was reasonably available

If the defendant could avoid the harm without committing the crime, necessity may not apply.

The defendant caused the emergency

Wrongfully creating the danger can undermine the defense.

The response was disproportionate

The harm caused cannot ordinarily be wildly greater than the harm avoided.

The conduct was retaliatory

Necessity is about preventing harm, not punishing someone.

The defendant acted for an unrelated purpose

An ordinary criminal act does not become necessary merely because an emergency existed somewhere in the background.

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The Model Penal Code Approach

The Model Penal Code provides an influential formulation of necessity, although it does not automatically constitute the law in every jurisdiction.

The Model Penal Code generally recognizes a justification when the defendant’s conduct is believed necessary to avoid a harm or evil to the defendant or another, and the harm avoided is greater than the harm caused or threatened by violating the law.

Cornell Legal Information Institute — Model Penal Code

The Model Penal Code approach is important because it illustrates the broader structure of necessity:

necessity → greater harm avoided → lesser harm caused.

But individual states may formulate the defense differently, and some statutes or common-law doctrines impose additional requirements.

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Federal Law and Necessity

Federal criminal law does not contain one universal necessity rule applicable to every federal offense.

The availability and formulation of necessity can depend on the particular offense, statutory language, and applicable federal case law.

Some federal courts recognize necessity under appropriate circumstances, but courts have also emphasized that the defense has strict requirements.

This is important because necessity is not a free-standing permission to violate federal statutes whenever a defendant believes doing so was beneficial.

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Evidence in Necessity Cases

Necessity cases often depend heavily on evidence concerning the emergency itself.

Relevant evidence may include:

• photographs;
• weather records;
• emergency communications;
• medical records;
• surveillance footage;
• witness testimony;
• geographic information;
• timestamps;
• police reports;
• expert evidence; and
• evidence concerning available alternatives.

For example, if a defendant claims that a natural disaster forced the person to enter private property, evidence concerning the severity and timing of the disaster may be critical.

The court must reconstruct the circumstances confronting the defendant at the time of the decision.

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The Problem of Hindsight

Necessity cases present a particularly strong risk of hindsight bias.

A court may know that:

“The disaster eventually passed.”

But the defendant may not have known that.

A medical emergency may later turn out to have been less serious than originally feared.

A storm may change direction.

A fire may stop spreading.

These later developments do not automatically determine whether the defendant’s decision was reasonable at the time.

Emergency decisions must often be evaluated in light of the information available when the decision was made.

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Necessity and Moral Responsibility

Necessity raises one of the oldest questions in criminal law:

Can breaking a rule become the right thing to do when following the rule would cause greater harm?

The answer is often yes, but only within carefully defined limits.

Imagine a person who breaks a door to rescue someone trapped inside a burning building.

The person has technically damaged property.

But most people would regard the rescue as morally justified.

Criminal law frequently reflects that intuition.

The doctrine of necessity formalizes the idea that legal rules should not always be applied mechanically when doing so would produce an obviously greater harm.

But the law must also prevent individuals from turning personal preferences into claims of necessity.

The difficult task is therefore distinguishing:

genuine necessity

from:

subjective convenience disguised as necessity.

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A Practical Framework for Analyzing Necessity

When analyzing a necessity defense, ask the following questions:

Step 1: What harm was threatened?

Identify the danger the defendant claims to have been avoiding.

Step 2: Was the danger serious?

Determine whether the threatened harm was sufficiently significant to justify extraordinary conduct.

Step 3: Was the danger imminent?

Ask whether immediate action was required.

Step 4: What did the defendant believe?

Identify the defendant’s understanding of the circumstances.

Step 5: Was that belief reasonable?

Apply the jurisdiction’s standard concerning reasonable perception.

Step 6: Was violating the law necessary?

Determine whether the criminal conduct was actually connected to preventing the threatened harm.

Step 7: Were lawful alternatives available?

If another reasonable and lawful option existed, necessity may be weakened or defeated.

Step 8: Did the defendant cause the emergency?

Determine whether the defendant’s own wrongful conduct created the situation.

Step 9: Was the response proportionate?

Compare the harm caused with the harm avoided.

Step 10: Did the defendant stop when the emergency ended?

Continuing the conduct after necessity disappears may destroy the justification.

Step 11: What does the jurisdiction require?

Finally, apply the particular statutory and case-law rules governing necessity.

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Common Misunderstandings

“Necessity means I can break any law during an emergency.”

No. The defense has specific legal requirements and varies by jurisdiction.

“If I believe something is necessary, that is enough.”

Not necessarily. The defendant’s belief may have to satisfy an objective reasonableness requirement.

“Necessity and duress are the same.”

No. Necessity generally involves circumstances or natural forces; duress generally involves coercion by another person.

“Necessity is the same as self-defense.”

No. Self-defense generally concerns unlawful force against a person. Necessity is broader and concerns avoiding a greater harm.

“I can claim necessity whenever breaking the law produces a better result.”

No. The doctrine generally requires a genuine emergency and the absence of adequate lawful alternatives.

“The emergency automatically excuses everything I do.”

No. The response must generally remain reasonably connected and proportionate to the danger.

“Necessity only applies to physical emergencies.”

Not necessarily. The doctrine can arise in different contexts, although its precise application depends heavily on the offense and jurisdiction.

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The Deeper Principle Behind Necessity

Necessity illustrates an important truth about criminal law:

Rules exist to protect human interests, and sometimes those interests conflict.

A law against damaging property protects ownership.

A law against trespass protects possession and privacy.

A law against unauthorized entry protects security.

But those interests can conflict with more fundamental interests such as human life and physical safety.

Imagine a person who must break a locked door to escape a fire.

The legal system must decide which interest deserves priority.

Necessity provides one answer:

When a genuine emergency creates a conflict between competing harms, the law may justify choosing the lesser harm to prevent the greater one.

But that principle cannot be unlimited.

If every person were free to disregard criminal laws whenever they believed their actions served a greater purpose, legal rules would become optional.

Necessity therefore operates at the boundary between legal obligation and practical survival.

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Key Takeaways

• Necessity is generally a justification defense.
• It may apply when otherwise criminal conduct was reasonably necessary to prevent a greater harm.
• The threatened harm is generally expected to be serious and sufficiently imminent.
• The defendant’s belief concerning the emergency may be important.
• Lawful alternatives can defeat or weaken the defense.
• The harm caused should generally be less serious than the harm avoided.
• A defendant’s responsibility for creating the emergency can matter.
• Necessity differs from self-defense, defense of property, and duress.
• Necessity is sometimes described as the choice of evils or lesser-evil defense.
• The Model Penal Code provides an influential formulation, but individual jurisdictions may differ.
• Necessity does not provide a general permission to violate criminal law whenever doing so seems advantageous.
• The defense is strongest when the defendant faced a genuine emergency and had no reasonable lawful alternative.

Frequently Asked Questions

What is necessity as a criminal defense?

Necessity is a justification defense that may apply when a defendant violated the law because doing so was reasonably necessary to prevent a greater harm.

Is necessity an affirmative defense?

It is generally treated as a justification defense, although the procedural rules and allocation of burdens vary among jurisdictions.

What is the lesser-evil principle?

The lesser-evil principle is the idea that conduct that would ordinarily be criminal may be justified when it prevents a substantially greater harm.

Is necessity the same as duress?

No. Necessity generally concerns dangerous circumstances, while duress generally involves threats or coercion by another person.

Can necessity justify damaging someone else’s property?

Potentially, if the damage was reasonably necessary to prevent a substantially greater harm and the jurisdiction recognizes the defense under the circumstances.

Can necessity justify breaking into a building?

Potentially. For example, entering a building to escape an immediate life-threatening emergency may raise necessity, particularly if no lawful alternative was available.

Does necessity apply when a person creates the emergency?

A defendant who wrongfully creates the emergency may face significant limitations on the defense, depending on the jurisdiction and circumstances.

Does the defendant have to choose the absolute least harmful option?

The precise legal standard varies, but the availability of reasonable lawful alternatives and the proportionality of the defendant’s response are generally important considerations.

Does necessity apply to every crime?

No. The defense depends on the jurisdiction, the offense, statutory language, and applicable case law.

Conclusion

Necessity recognizes that criminal law sometimes operates in a world of competing harms rather than simple choices between lawful and unlawful conduct.

A person may face a situation in which every available option carries a cost. One choice may violate a criminal law, while another may expose a person to death, serious injury, or another substantially greater harm.

The necessity defense provides a legal framework for evaluating that difficult choice.

Its central principle is simple:

When extraordinary circumstances make unlawful conduct reasonably necessary to prevent a greater harm, the law may regard that conduct as justified.

But necessity is deliberately narrow. The danger must generally be genuine and sufficiently serious; the response must be reasonably connected to preventing it; lawful alternatives must generally be inadequate; and the harm caused must not be disproportionate to the harm avoided.

Necessity therefore does not mean that criminal laws disappear during emergencies.

Rather, it recognizes something deeper about criminal responsibility: sometimes the legally justified choice is not the choice that follows the ordinary rule, but the choice that prevents the greater harm.