PastPaperHero | Intentional torts - Defenses to claims for physical harms

Learning Outcomes

This article explains the principal defenses to intentional torts involving physical harm and clarifies how they are tested on the MBE, including:

identifying when consent is valid, implied, invalid, or exceeded in scope in battery, assault, and false‑imprisonment fact patterns;
applying self-defense and defense of others, with attention to reasonable belief, proportional force, deadly-force limits, and retreat or castle-doctrine rules;
distinguishing defense of property and recapture of chattels from defenses protecting persons, especially the absolute bar on using deadly force solely for property;
analyzing public and private necessity, including when each defense arises, the effect on damages, and how necessity interacts with trespass and conversion claims;
evaluating the privilege of arrest for police and private citizens, focusing on felonies versus misdemeanors, presence requirements, and reasonable-mistake rules;
using the shopkeeper’s privilege to assess the legality of short investigatory detentions in theft scenarios on the exam;
recognizing when parental discipline and similar custodial privileges justify otherwise tortious contact with children;
spotting when any asserted defense fails because the circumstances do not create a privilege or the actor uses unreasonable or excessive force.

MBE Syllabus

For the MBE, you are required to understand defenses to intentional torts causing physical harm, with a focus on the following syllabus points:

When consent is valid, implied, or invalidated by fraud, mistake, duress, or lack of capacity.
Self-defense and defense of others: reasonable belief, reasonable force, deadly force, and retreat rules.
Defense of property, recapture of chattels, and limits on mechanical devices and “hot pursuit.”
Necessity (public and private) as a defense to trespass to land and chattels, including the duty to pay for damage.
Privilege of arrest (police and private citizens) and shopkeeper’s privilege as defenses to false imprisonment and related torts.
Parental discipline as a privilege to use reasonable force on children.
Situations where these defenses fail because force is excessive, the privilege does not arise, or a mistake is unreasonable.

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.

Which of the following is generally NOT a valid defense to a claim of battery?
1. Consent
2. Self-defense
3. Defense of property using deadly force
4. Defense of others
A shopkeeper reasonably suspects a customer of theft and detains her for questioning in a reasonable manner and time. What defense is most likely available?
1. Consent
2. Shopkeeper’s privilege
3. Necessity
4. Defense of property
If a person uses force to protect another from an imminent battery, which requirement must be met for the defense to succeed?
1. The person aided must actually have the right to self-defense
2. The defender must be related to the person aided
3. The defender must use only reasonable force
4. The defender must retreat before intervening

Introduction

Intentional torts involving physical harm—such as battery, assault, and false imprisonment—are often straightforward to prove on the MBE. The more difficult part is seeing whether the defendant can avoid liability by invoking a privilege or defense. These defenses do not deny that the tort’s elements are satisfied; instead, they justify or excuse the conduct.

The main defenses tested are:

Consent
Self-defense
Defense of others
Defense of property (including recapture of chattels)
Necessity (public and private)
Privilege of arrest and shopkeeper’s privilege
Parental discipline

On exam questions, once you see a prima facie intentional tort, immediately ask:

Did the plaintiff consent?
Was the defendant acting to protect a person (self or others) or property?
Was there an emergency or public danger (necessity)?
Was the defendant detaining or arresting someone (privilege of arrest/shopkeeper)?
Was the defendant a parent or guardian disciplining a child?

Then check whether the conditions for the privilege existed and whether the force used was reasonable and proportionate. Excessive or unnecessary force usually destroys the defense.

Key Term: Consent
A defense to intentional torts where the plaintiff voluntarily agrees to the defendant’s conduct, expressly or impliedly, provided the consent is valid (not vitiated by fraud, mistake, duress, or incapacity) and not exceeded in scope.

Key Term: Self-Defense
The privilege to use reasonable force to prevent imminent harmful or offensive contact to oneself, based on a reasonable belief that such force is necessary; deadly force is limited to threats of death or serious bodily harm.

Key Term: Defense of Others
The privilege to use reasonable force to protect a third person from imminent harm, where the defender reasonably believes that intervention is necessary and that the person aided would be entitled to use self-defense.

Key Term: Defense of Property
The privilege to use reasonable, non-deadly force to prevent or terminate an unlawful intrusion on or dispossession of one’s real or personal property.

Key Term: Necessity
A defense to intentional torts against property when the defendant interferes with another’s property to prevent a greater harm. Public necessity is a complete defense; private necessity is a qualified defense requiring payment for actual damage caused.

Key Term: Privilege of Arrest
The privilege to detain or arrest another for criminal conduct under specific conditions, using reasonable force, thereby providing a defense to intentional torts such as false imprisonment, battery, and assault.

Key Term: Parental Discipline
A privilege allowing parents (and sometimes those in loco parentis) to use reasonable force as necessary to discipline their children, thereby providing a defense to intentional torts such as battery and false imprisonment.

Consent can completely bar liability for intentional torts, but only if it is valid and the defendant acts within the scope of that consent.

Express consent: The plaintiff communicates permission in words or writing (“You may operate on my shoulder,” “Go ahead and hit me; it’s part of the game.”).
Implied consent: Consent inferred from conduct, custom, or the circumstances:
- Everyday social contacts: Riding a crowded subway implies consent to minor, customary bumps.
- Participation in sports: Joining a contact sport implies consent to contacts within the rules and ordinary incidents of the game.
- Medical emergencies: If a patient is unconscious or unable to consent, and immediate treatment is necessary to preserve life or prevent serious harm, a physician may act under implied consent, unless there is reason to know the patient would refuse (e.g., clearly stated religious objection).

Consent is invalid if:

Lack of capacity: Minors, intoxicated persons, or mentally incompetent persons may lack capacity to consent, especially to complex or risky procedures.
Mistake:
- Consent induced by the plaintiff’s own mistake is generally valid.
- If the defendant causes the mistake or knows of it and takes advantage, consent is invalid.
Fraud:
- Fraud as to an essential matter (e.g., the nature of the act) vitiates consent (e.g., sexual intercourse misrepresented as a medical exam).
- Fraud as to a collateral matter (e.g., lying about wealth) usually does not.
Duress: Consent given under threat of immediate harm is invalid.
Criminal acts:
- Majority rule: Consent can still be a defense to an intentional tort even if the relevant conduct is criminal, unless the statute aims to protect the consenting party (e.g., statutory rape).

Even valid consent is limited by scope: a defendant is liable if they go beyond what was agreed to or reasonably understood (e.g., performing an unauthorized additional surgery unrelated to the consented procedure).

Worked Example 1.1

A football player punches another during a match. The injured player sues for battery. The defendant argues that all players consented to physical contact by joining the game. Is this a valid defense?

Answer:
Yes, but only in part. By participating in a contact sport, players are deemed to have impliedly consented to contacts that are within the rules and customs of the game. If the punch occurred during a legitimate tackle within the ordinary roughness of play, consent would bar liability. If the punch was well outside the rules—for example, a deliberate blow to the head after the play ended, or to a helmetless opponent when that is not part of the game’s custom—then the conduct exceeds the scope of consent and the defendant remains liable.

Self-Defense

Self-defense is heavily tested because it often appears in battery and assault questions. The key elements are:

Reasonable belief in an imminent threat of unlawful force.
Reasonable force used to prevent that threat.
Proportionality between the threat and the response.

The defendant need not be correct about the danger; it is enough that a reasonable person in the same circumstances would believe force is necessary.

Non-Deadly vs Deadly Force

Non-deadly force: May be used when reasonably necessary to prevent any imminent harmful or offensive contact.
Deadly force: Force intended or likely to cause death or serious bodily harm may be used only if the defendant reasonably believes she is facing an imminent threat of death or serious bodily harm.

Most jurisdictions do not require retreat before using non-deadly force.

Retreat Rules and the “Castle Doctrine”

Non-deadly force: No duty to retreat.
Deadly force:
- Majority: No general duty to retreat if deadly force is otherwise justified.
- Minority: Duty to retreat (if safe to do so) before using deadly force outside the home.
- Castle doctrine (widely accepted): No duty to retreat in one’s own home.

Initial Aggressor

An initial aggressor generally may not claim self-defense if they started the confrontation.

Exception: If the initial aggressor uses non-deadly force and the other party escalates to deadly force, the original aggressor may use deadly force in self-defense.
The initial aggressor can regain the right to self-defense by clearly withdrawing and communicating the withdrawal, but only if the other party continues the aggression.

Bystanders

If a defendant acting in legitimate self-defense accidentally injures a bystander, the self-defense privilege extends to this harm, as long as the defendant was not negligent toward the bystander.

Exam Warning:
A common trap is a defendant who uses clearly excessive force (e.g., shooting at a minor slap). Even if self-defense initially applies, using greater force than necessary destroys the defense and creates liability.

Defense of Others

Defense of others mirrors self-defense but focuses on protection of a third person.

The defender may use reasonable force when they reasonably believe:
- The person aided faces an imminent threat of unlawful force, and
- The person aided would be entitled to use self-defense.

Modern (majority) rule: it is enough that the defender’s belief is reasonable, even if the person aided in fact had no right to self-defense (e.g., the defender reasonably but mistakenly thought A was being attacked when A was actually the aggressor). Older “step-into-the-shoes” rules (liability turns on the actual rights of the person aided) are rarely tested on the MBE.

Worked Example 1.2

A bystander sees a stranger being attacked and intervenes, using reasonable force to stop the attacker. The attacker sues the bystander for battery. What defense applies?

Answer:
Defense of others. The bystander is privileged if they reasonably believed that intervention was necessary to prevent the stranger from suffering imminent harm and used only reasonable force. The defense succeeds even if it later turns out the stranger started the fight, as long as the belief was reasonable.

Defense of Property

Defense of property protects real property (land) and personal property (chattels).

A possessor may use reasonable, non-deadly force to prevent or terminate:

A trespass on land, or
A theft, destruction, or wrongful dispossession of chattels.

Before using force, the possessor must usually request the intruder to desist or leave, unless doing so would be dangerous or clearly futile.

Crucially:

Deadly force is never permitted solely to protect property.
You may not use deadly mechanical devices such as spring guns, traps, or attack dogs programmed to inflict serious harm.

Recapture of Chattels

A possessor may use reasonable, non-deadly force to recapture personal property when:

The property was wrongfully taken (e.g., stolen), and
The possessor is in fresh or “hot” pursuit, and
A request to return has been made (unless futile or dangerous).

If the initial taking was lawful (e.g., a bailee, borrower, or customer), only peaceful means (e.g., legal action) may be used to recover the chattel.

Force to Regain Possession of Land

Common law: Allowed reasonable force to recapture land.
Modern rule: No privilege to use force to retake land; the owner must use legal process (ejectment, unlawful detainer, etc.).

Worked Example 1.3

A homeowner sees a burglar breaking into his shed and uses a spring-loaded gun to protect his property, injuring the burglar. The burglar sues for battery. Can the homeowner claim defense of property?

Answer:
No. While reasonable, non-deadly force may be used to protect property, deadly force and deadly mechanical devices may not be used solely to protect property. The spring gun is a deadly mechanical device, so the defense of property fails and the homeowner is liable for battery.

Exam Warning:
Using deadly force (or traps) to protect property alone is never justified on the MBE. Deadly force must be tied to defending persons, not just things.

Shopkeeper’s Privilege

A specialized application of defense of property and privilege of arrest is the shopkeeper’s privilege, which functions as a defense to false imprisonment.

A shopkeeper (or equivalent merchant) may:

Detain a person for investigation of suspected theft if:
- They have a reasonable belief that the person has stolen or is attempting to steal goods,
- The detention is conducted in a reasonable manner (no excessive force or public humiliation), and
- The detention lasts for a reasonable time to investigate or wait for authorities.

If these conditions are satisfied, the detention is privileged and not false imprisonment.

Necessity

Necessity arises when the defendant intentionally interferes with property to prevent a greater harm. It is almost always a defense to property torts (trespass to land, trespass to chattels, conversion), not to intentional torts against persons.

Necessity can be:

Public necessity, or
Private necessity.

Public Necessity

Public necessity exists when the defendant reasonably believes that interfering with private property is necessary to avert an imminent public disaster or protect a large number of people (e.g., destroying a building to create a firebreak and stop a citywide fire).

Effects:

It is a complete defense: the defendant is not liable for any damage, even actual damage.
The belief must be reasonable, but need not be correct.

Private Necessity

Private necessity exists when the defendant reasonably believes that interfering with another’s property is necessary to prevent serious harm to themselves or a small number of people or property (e.g., tying a boat to a private dock during a storm to save the boat and occupants).

Effects:

Private necessity creates a qualified privilege:
- The defendant is not liable for technical trespass (no nominal or punitive damages).
- The defendant must pay for actual damage caused (compensatory damages).
The landowner may not use force to eject the defendant while the necessity continues; doing so can itself be a tort.

Worked Example 1.4

A boater, caught in a sudden storm and reasonably fearing that her boat would capsize, drove the boat up to a pier, exited the boat, and tied the boat to the pier. The pier was clearly marked with “NO TRESPASSING” signs. The owner ran up, told her the boat could not remain, and despite her protests and offer to pay, untied the boat and pushed it away. The boat was lost at sea. Is the owner liable?

Answer:
Yes. The boater had a privilege of private necessity to enter and use the pier to protect her property and safety. The owner was not entitled to terminate that privilege by using force that foreseeably caused loss of the boat. Under private necessity, the boater would owe the owner for any actual damage to the pier, but the owner is liable for the loss of the boat caused by wrongfully interfering with the privileged entry.

Privilege of Arrest

The privilege of arrest (and related detention) can defeat claims of false imprisonment, battery, and assault, but it is strictly limited.

Arrest by Private Citizens

A private citizen is privileged to arrest (or detain) another for a felony if:

A felony has actually been committed, and
The citizen has reasonable grounds to suspect that the person arrested committed it.

Key points:

A reasonable mistake as to identity of the felon is allowed (privilege remains).
A mistake as to whether a felony was actually committed is not allowed; if no felony occurred, the privilege fails, even if the citizen reasonably thought it did.

For misdemeanors, a private person may arrest only if:

The misdemeanor amounts to a breach of the peace, and
It is committed in the arrestor’s presence.

Arrest by Police Officers

A police officer is privileged to arrest if they:

Have a reasonable belief that a felony has been committed, and
Reasonably believe that the person arrested committed it.

If a felony has in fact been committed, officers may arrest a suspect based on a reasonable but mistaken belief about identity and avoid tort liability. However, if no felony was committed at all, an officer who arrests solely on that mistaken belief can be subject to tort liability.

For misdemeanors:

An officer may arrest only if the misdemeanor is committed in the officer’s presence, usually limited to misdemeanors involving a breach of the peace.

The privilege extends only to reasonable force in making the arrest.

Worked Example 1.5

A private citizen hears a scream, runs outside, sees a man running away from a house carrying a television, and tackles him, detaining him until the police arrive. In fact, there had been a burglary. The detained man turns out to be a neighbor chasing the real thief. If the neighbor sues for false imprisonment, does the citizen have a defense?

Answer:
Yes. A felony burglary actually occurred, and the citizen had reasonable grounds to suspect the neighbor (running away carrying a television). A reasonable mistake as to identity does not defeat the privilege of arrest for a felony, so the citizen has a valid defense to false imprisonment.

Parental Discipline

Parents and those standing in a parental role (such as legal guardians) have a limited privilege to use force to discipline children.

The force must be reasonable in degree and kind, taking into account:
- The child’s age and size,
- The child’s behavior,
- The necessity for discipline, and
- The potential for serious injury.

Excessive or abusive force (e.g., severe beatings, dangerous restraints) falls outside the privilege and can constitute battery, assault, or false imprisonment. Some jurisdictions extend a similar limited privilege to teachers or caretakers.

Worked Example 1.6

A parent lightly swats a 10-year-old child on the backside after the child runs into a busy street despite repeated warnings. The child later sues for battery. Can the parent successfully assert a defense?

Answer:
Yes. The parent’s conduct falls within the privilege of parental discipline. The swat was mild, given for safety-related behavior, and reasonably proportionate. The force was used to protect the child and was not excessive, so it provides a complete defense to battery.

Worked Example 1.7

A clothing store security guard sees a customer put a shirt in her bag and walk toward the door. The guard, reasonably suspecting shoplifting, stops the customer just inside the exit and escorts her to a back office. He questions her for 10 minutes, checks the bag, and finds the customer actually paid. She sues for false imprisonment. Does the store have a defense?

Answer:
Yes. The store may rely on the shopkeeper’s privilege. The guard had a reasonable belief of theft, detained the customer in a reasonable place (store office) for a reasonable time (10 minutes), and used no unreasonable force or humiliation. The detention is therefore privileged and not false imprisonment.

Revision Tip:
For every defense, ask:

Did the privilege arise (reasonable belief, proper purpose)?

Was the force or interference no more than necessary?
If either fails, the defense is likely lost.

Key Point Checklist

This article has covered the following key knowledge points:

Consent is a complete defense only if the plaintiff has capacity, is not acting under fraud, mistake, or duress as to an essential matter, and the defendant stays within the scope of that consent.
Self-defense permits reasonable force against an imminent threat based on a reasonable belief; deadly force is allowed only when facing a threat of death or serious bodily harm, with limited retreat requirements.
Defense of others is available when the defender reasonably believes intervention is necessary and that the person aided would be entitled to use self-defense; the defender’s reasonable mistake is protected.
Defense of property allows only reasonable, non-deadly force to protect or recapture property; deadly force and deadly mechanical devices can never be used solely to protect property.
Recapture of chattels is permitted only against a wrongful taker, in hot pursuit, after a request for return, and only with non-deadly force.
Necessity justifies intentional interference with property; public necessity is a complete defense, while private necessity is a qualified defense requiring payment for actual damage but preventing ejection by force.
The privilege of arrest allows police and, in limited circumstances, private citizens to arrest or detain individuals suspected of crimes, but only for appropriate crimes and with reasonable force; mistakes about identity are more readily excused than mistakes about whether a felony occurred.
Shopkeeper’s privilege authorizes brief, reasonable detentions for investigation of suspected shoplifting and operates as a defense to false imprisonment.
Parental discipline permits reasonable force to discipline children; excessive or abusive force falls outside the privilege and creates liability.
In all defenses, excessive or disproportionate force usually destroys the privilege, even if it existed initially.

Key Terms and Concepts

Consent
Self-Defense
Defense of Others
Defense of Property
Necessity
Privilege of Arrest
Parental Discipline

Intentional torts - Defenses to claims for physical harms