Intentional torts - Necessity

Learning Outcomes

This article explains the necessity defense in intentional torts, including:

• Identifying when necessity is available as a defense to trespass to land, trespass to chattels, and conversion, and recognizing when the defense is unavailable because the interference is negligent or directed at a person rather than property.
• Distinguishing precisely between public necessity (complete defense) and private necessity (qualified defense), and predicting the consequences of each for liability, nominal damages, and compensatory damages.
• Determining when a defendant must compensate the property owner for actual damage despite the necessity privilege, and when the owner is barred from recovering at all.
• Applying necessity rules methodically to common MBE-style emergency fact patterns involving fires, floods, storms, runaway vehicles, and threatened third parties.
• Evaluating whether the elements of necessity are satisfied—serious threatened harm, imminence, lack of reasonable alternatives, and proportional, reasonably necessary conduct.
• Spotting typical exam traps, including confusion with self-defense, defense of others, defense of property, consent, and the criminal-law version of necessity, and accurately labeling the doctrine being tested.
• Using the public/private necessity distinction to structure rule statements, short-answer justifications, and process-of-elimination strategies on multiple-choice questions.

MBE Syllabus

For the MBE, you are required to understand the necessity defense as it applies to intentional torts involving property, with a focus on the following syllabus points:

• Define necessity as a defense to intentional torts involving property.
• Distinguish between public necessity (complete defense) and private necessity (qualified or partial defense).
• Identify when necessity excuses liability for trespass to land, trespass to chattels, or conversion.
• Recognize when compensation for property damage is still required despite the defense.
• Apply necessity principles to fact patterns involving emergencies or threats to persons or property.
• Recognize the limits of necessity, including its inapplicability to intentional torts against the person (e.g., battery) and situations where the harm is not acute or imminent.

Test Your Knowledge

Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, remember to look more closely at that area during your revision.

1. Which of the following best describes the defense of public necessity?
   1. It is available only to government officials.
   2. It is a complete defense to intentional torts involving property when the act protects the public from imminent harm.
   3. It excuses liability for personal injury but not property damage.
   4. It applies only to trespass to land, not to chattels.
2. In which situation is a person who enters another’s property to protect their own property from harm still liable for actual damage caused?
   1. Public necessity.
   2. Private necessity.
   3. Consent.
   4. Self-defense.
3. Which of the following is true regarding private necessity?
   1. It is a complete defense to all intentional torts.
   2. It excuses all liability for property damage.
   3. It allows entry but requires payment for actual harm caused.
   4. It applies only to government actors.

Introduction

Necessity is a defense to certain intentional torts involving property, such as trespass to land, trespass to chattels, and conversion. It arises when a person intentionally interferes with another’s property to prevent a greater harm. The law recognizes that, in emergencies, it may be reasonable—even socially desirable—to invade someone else’s property rights to avoid serious harm.

The MBE expects you to know not just that necessity exists, but exactly when it applies, to which torts, and with what consequences for liability and damages.

Key Term: Necessity
A defense to intentional torts involving property, where the defendant intentionally interferes with another’s property because doing so is reasonably and apparently necessary to prevent a threatened harm to the public or to specific persons or property.

General Requirements for Necessity

Before classifying an act as public or private necessity, make sure the basic elements of necessity are satisfied. On MBE fact patterns, look for:

• Threat of serious harm
  The defendant must be responding to an emergency or other severe danger—e.g., storm, flood, fire, runaway vehicle, or similar acute danger. A long-term or routine inconvenience (like being late for a meeting) is not enough.

• Imminence (or near-imminence)
  The danger must be immediate or very close at hand. Courts talk about an “imminent” or “apparently imminent” harm.

Key Term: Imminent Harm
A serious threat that is occurring or about to occur, such that immediate action is reasonably necessary; remote or speculative risks are not imminent.

• Reasonable and proportionate response
  The defendant’s conduct must be reasonably necessary to avoid the harm, and the harm avoided must be greater than the property interest interfered with. The test is objective: would a reasonable person in the same circumstances believe the interference was necessary?

• No reasonable alternative
  If the defendant could have avoided the harm without invading the plaintiff’s property (e.g., by moving elsewhere at negligible cost or risk), necessity usually fails.

• Intentional interference with property
  Necessity is a defense only when the defendant intentionally enters land or interferes with chattels. It does not apply to negligence and does not justify intentional torts to the person (such as battery) on the MBE.

Once these baseline requirements are met, classify the situation as either public or private necessity.

Types of Necessity

Necessity is divided into public necessity and private necessity. The distinction is critical for the MBE, as it determines whether the defendant is liable for property damage.

Public Necessity

Public necessity arises when a person (including private citizens) intentionally interferes with property to prevent a threat to the community or a significant group. The act must be reasonably necessary to avert an imminent public disaster, such as fire, flood, or disease.

Key Term: Public Necessity
A defense to intentional property torts where the defendant acts to protect the public or a substantial number of people from imminent or serious harm; it is a complete defense, excusing all liability for the trespass and resulting property damage.

Key features of public necessity:

• Protects a large group or the community at large
  Examples: stopping a rapidly spreading wildfire approaching a town, containing a contagious disease outbreak, preventing a riot‑related explosion.

• Available to private actors and officials
  It is not limited to government personnel. A private citizen who destroys a building to stop a fire from engulfing a neighborhood may invoke public necessity if the action was reasonable.

• Requires objective reasonableness
  The actor must reasonably believe the interference is necessary; a purely subjective, unreasonable belief will not suffice.

If public necessity applies, the defendant is free from liability for both the invasion (e.g., trespass) and any resulting damage to the property.

Private Necessity

Private necessity occurs when a person intentionally interferes with property to protect their own interests or those of a limited number of people. The act must be reasonably necessary to prevent serious harm to the actor, their property, or a small group.

Key Term: Private Necessity
A defense to intentional property torts where the defendant acts to protect their own or a few persons’ interests from serious and imminent harm; it is a qualified defense, excusing liability for the trespass itself but not for actual property damage caused.

Private necessity typically arises when:

• A person takes refuge on another’s land during a sudden storm.
• A driver steers a car onto a lawn to avoid a collision.
• Someone trespasses to retrieve their own chattel threatened by sudden danger (e.g., a tarp blown onto a neighbor’s property during a storm).

Important limits:

• The harm must be acute and unforeseeable. Needing food because of chronic poverty or trespassing for convenience does not qualify.
• The defendant must not treat the plaintiff’s property as expendable; only damage that is reasonably necessary to avert the greater harm is protected.

Key Term: Qualified Privilege
A defense that shields the defendant from liability for committing the tort (e.g., trespass) but still requires payment of compensatory damages for any actual harm caused.

Scope of the Defense

Once you determine whether necessity is public or private, focus on the consequences for liability and damages.

Public Necessity—Complete Defense

If public necessity applies, the defendant is not liable for the trespass or for any resulting property damage, even if the property owner suffers a substantial loss. This rule encourages decisive action to prevent widespread harm.

• No liability for trespass
  The owner cannot recover even nominal damages for the entry.

• No liability for property damage
  Destruction or damage reasonably necessary to protect the public is non-compensable as a matter of tort law.

• Reasonable mistake still protected
  If the defendant reasonably—but mistakenly—believed a public disaster threatened, public necessity still operates as a defense.

Private Necessity—Qualified Defense

If private necessity applies, the defendant is not liable for the trespass itself but must pay for any actual damage caused to the property. The property owner cannot exclude the defendant while the necessity continues, but compensation is required for losses.

Key consequences:

• Trespass is privileged
  The land possessor cannot recover nominal damages for the mere entry and may not use force to eject the defendant as long as the emergency continues.

• Liability for actual damage only
  The defendant must pay for physical damage actually caused by their entry or actions, but is not liable for purely technical or nominal harms.

• Owner’s use of force may create liability
  If a landowner uses force to remove someone who is privileged by private necessity, and the entrant is injured or their property is harmed, the landowner can be liable for battery or property damage.

Private necessity also aligns with the rule that a person may trespass to retrieve their own chattel that is on another’s land through no fault of their own (e.g., blown by the wind). That trespass is privileged, but the actor must pay for any damage caused in the process.

Worked Example 1.1

A firefighter, acting without a warrant, demolishes a homeowner’s fence to create a firebreak and stop a rapidly spreading wildfire threatening the town. The homeowner sues for trespass and property damage. Is the firefighter liable?

Answer:
No. This is public necessity. The firefighter acted reasonably to protect the public from imminent harm. Because public necessity is a complete defense, the firefighter is not liable for either the trespass or the resulting damage to the fence.

Worked Example 1.2

During a severe storm, a boater ties their vessel to a private dock to avoid sinking. The boat survives, but the dock is damaged. The dock owner sues for trespass and damage. Is the boater liable?

Answer:
The boater can assert private necessity. The storm created an imminent threat to the boater and the boat, making entry reasonably necessary. Private necessity is a qualified privilege: the boater is not liable for trespass, but must pay for the actual damage to the dock.

Worked Example 1.3

To stop an out-of-control truck from rolling down a hill toward a busy intersection, a driver steers her own car into a homeowner’s empty garage, destroying the garage door and damaging the frame. The homeowner sues for trespass and property damage. The driver argues public necessity. Does the defense apply?

Answer:
Yes, public necessity likely applies. The driver acted to prevent a serious threat to many people at the intersection, not just to her own person or property. Her entry and damage were reasonably necessary to avert a public calamity, so she is not liable for either the trespass or the property damage.

Worked Example 1.4

A motorist parks her car at the top of a stranger’s steep driveway to avoid floodwaters covering the road. While she is gone, the homeowner rolls the car back down to the road, where floodwaters destroy it. The motorist sues for damage to her car. How should the case be decided?

Answer:
The motorist was privileged by private necessity to use the driveway to avoid imminent harm to her property. The homeowner had no right to expel her car while the necessity continued. By rolling the car back into danger, the homeowner became liable for the resulting damage to the car.

Worked Example 1.5

A hungry person, unemployed for several months, regularly enters a grocery store’s private storeroom at night and takes food without paying. When caught, he asserts the defense of necessity to a conversion claim. Is necessity available?

Answer:
No. Necessity requires an acute, emergency‑type danger and an imminent threat, not a chronic or long-standing need. The defendant’s situation, while serious, does not involve an immediate danger justifying the intentional interference with property, so neither public nor private necessity applies.

Exam Warning

On the MBE, do not confuse public necessity (complete defense, no liability for damage) with private necessity (qualified defense, must pay for actual harm). Carefully read the facts to determine whose interests are being protected and whether the threat is to the public at large or only to a specific person or small group.

Additional exam pitfalls:

• If the actor is protecting only themselves or a small number of identifiable persons, assume private necessity, even if the harm is serious.
• If the fact pattern involves harming a person (e.g., pushing someone into danger to protect property), necessity is not a defense to battery or similar intentional torts; look instead at self-defense or defense of others.
• Do not confuse the torts doctrine of necessity with the criminal-law necessity defense; the MBE usually tests necessity here as a property-tort defense.

Revision Tip

If the act protects the public or a large group, necessity is a complete defense (public necessity). If it protects only the actor or a few others, necessity excuses the trespass but not property damage (private necessity). Always ask: “Who is being protected, and from what kind of threat?”

Key Point Checklist

This article has covered the following key knowledge points:

• Necessity is a defense to intentional torts involving property, particularly trespass to land, trespass to chattels, and conversion.
• Necessity requires a serious, imminent threat and conduct that is reasonably and apparently necessary to avert that harm.
• Public necessity protects actions taken to avert imminent harm to the community or a substantial number of people.
• Public necessity is a complete defense: no liability for trespass and no liability for resulting property damage, if the response was reasonable.
• Private necessity protects actions taken to prevent serious harm to oneself, one’s property, or a limited number of persons.
• Private necessity is a qualified (incomplete) defense: no liability for the trespass, but compensation is required for actual property damage caused.
• Under private necessity, the property owner may not use force to expel the privileged entrant while the emergency continues; doing so can create liability for personal or property harm.
• Necessity can justify a trespass to retrieve chattels that come onto another’s land through no fault of the owner, but the actor must pay for any damage caused.
• Necessity does not apply to intentional torts against persons such as battery; separate defenses (e.g., self-defense, defense of others) govern those situations.
• For exam purposes, carefully distinguish necessity from consent, defense of property, and criminal-law necessity, and focus on who is being protected and whether the defense is complete or qualified.

Key Terms and Concepts

• Necessity
• Public Necessity
• Private Necessity
• Imminent Harm
• Qualified Privilege