Intentional torts - Consent

Learning Outcomes

This article details the defense of consent in the context of intentional torts, including:

• distinguishing express consent, implied consent by conduct, and consent implied by law in emergency scenarios;
• assessing the plaintiff’s capacity to consent based on age, mental condition, and intoxication in bar-style fact patterns;
• determining whether the defendant’s conduct remained within, or exceeded, the temporal, spatial, and risk-related scope of consent;
• evaluating when consent is revoked and how post‑revocation conduct exposes the defendant to liability for battery or false imprisonment;
• analyzing how fraud, duress, and mistake vitiate apparent consent, with emphasis on essential versus collateral misrepresentations;
• applying consent principles in medical-treatment questions, distinguishing no-consent battery from negligent failure to obtain informed consent;
• applying implied consent and scope analysis to athletic contests, mutual combat scenarios, and “crowded world” everyday contacts;
• examining how illegality, public policy limits, and third‑party or substituted decision‑makers affect the availability of the consent defense on the MBE.

MBE Syllabus

For the MBE, you are required to understand consent as an affirmative defense to intentional torts, with a focus on the following syllabus points:

• Identifying types of consent: express, implied by conduct, and implied by law.
• Assessing the validity of consent based on the plaintiff’s capacity.
• Determining whether the defendant’s conduct exceeded the scope of consent given.
• Analyzing situations where consent is vitiated by fraud, duress, or mistake.
• Applying consent principles in medical treatment, athletic activities, and mutual combat.
• Distinguishing between consent that negates an element of the tort (e.g., “offensiveness” in battery) and consent as an affirmative defense.

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 forms of consent is generally inferred from a person's conduct or the surrounding circumstances?
   1. Express consent
   2. Implied consent
   3. Consent implied by law
   4. Statutory consent
2. A boxer agrees to participate in a sanctioned boxing match according to established rules. During the match, the opponent punches the boxer, causing injury. If the boxer sues the opponent for battery, the opponent's strongest defense is:
   1. Self-defense
   2. Defense of others
   3. Consent
   4. Necessity
3. A surgeon performs emergency surgery on an unconscious patient brought to the hospital after a car accident. The patient had not given prior permission for surgery. The surgery saves the patient's life. If the patient later sues the surgeon for battery, the surgeon's best defense would likely be:
   1. Express consent
   2. Implied consent by law (emergency)
   3. Necessity
   4. Absence of intent

Introduction

Consent is a primary defense to most intentional torts. If a plaintiff consents to the defendant's conduct, the defendant is generally not liable for that conduct, even if it would otherwise be tortious. Consent negates the wrongful element of the defendant's conduct. The central idea is that a person cannot recover for harm resulting from conduct to which they willingly exposed themselves.

Consent is evaluated under an objective standard: the question is whether the defendant reasonably believed, based on the plaintiff’s words or conduct, that the plaintiff agreed to the contact or confinement. Secret, uncommunicated willingness is not enough; the plaintiff must manifest consent in some way.

Consent can be given expressly, through words, or impliedly, through conduct or circumstances. In some situations, the law itself implies consent (especially in emergencies). However, for consent to be valid:

• The person consenting must have the capacity to consent.
• The consent must not have been obtained through fraud, duress, or a material mistake known to the defendant.
• The defendant's conduct must not exceed the scope of the consent given.
• In some situations, public policy limits what a person may validly consent to (for example, serious maiming).

Key Term: Consent
A plaintiff's voluntary and apparent agreement to the defendant's conduct, evaluated under an objective standard, which negates the wrongfulness of that conduct and serves as a defense to intentional tort liability.

Consent operates as a defense to intentional torts such as battery, assault, false imprisonment, and trespass to land or chattels. It is particularly important on the MBE in battery and sports/medical scenarios.

Types of Consent

Consent can manifest in several ways.

• Express Consent: The plaintiff explicitly communicates consent either verbally or in writing (e.g., signing a consent form for surgery; verbally agreeing, “You can punch me once in the arm as a joke.”).
• Implied Consent by Conduct: Consent is inferred from the plaintiff's actions or conduct in the circumstances (e.g., voluntarily participating in a contact sport; extending an arm for a vaccination in a clinic).
• Implied Consent by Law: In certain emergency situations where the plaintiff is unable to consent, the law implies consent if immediate action is necessary to save the plaintiff's life or protect against serious harm, and a reasonable person would be expected to consent under the circumstances.

Key Term: Express Consent
Consent explicitly given by the plaintiff through words (oral or written) that a reasonable person would understand as permission for the conduct.

Key Term: Implied Consent
Consent inferred from the plaintiff's conduct, silence in context, custom, or the surrounding circumstances, where a reasonable person would interpret the plaintiff as agreeing to the contact.

Key Term: Implied Consent by Law
Consent deemed to exist as a matter of law in emergency circumstances when the plaintiff cannot consent and immediate action is reasonably necessary to prevent death or serious bodily harm.

Some additional points about how these forms of consent are tested:

• Everyday social and “crowded world” contacts: By moving about in public, people are taken to consent to minor, ordinary contacts (e.g., jostling on a crowded subway) that a reasonable person would expect.
• Custom and usage: Consent may be implied from established social or professional customs. For example, in a busy barbershop, sitting in the chair after being called is implied consent to a haircut and the associated touching.

Requirements for Valid Consent

For consent to be an effective defense, several conditions must be met.

Capacity to Consent

The person giving consent must have the legal and factual capacity to do so. Capacity turns on whether the person can understand the nature and consequences of the act.

Key Term: Capacity to Consent
The ability of a person to understand the nature and consequences of the conduct to which they are agreeing such that their consent is legally effective.

Lack of capacity can arise from:

• Infancy (minor status):
  Minors are often treated as having limited capacity. For many everyday, age-appropriate interactions, a minor’s consent is effective (e.g., roughhousing with friends, age-appropriate sports). However, consent to serious invasions of personal integrity, particularly those with significant medical risk or sexual conduct with adults, is often ineffective as a matter of law or public policy.

• Mental Incompetence:
  Individuals lacking the mental ability to understand the nature and consequences of the act cannot give valid consent. For example, consent from a person with severe cognitive impairment to a hazardous medical procedure is usually invalid; a guardian’s or court’s substituted consent may be required.

• Intoxication:
  Consent may be invalid if the plaintiff was intoxicated to the point of incapacity, and the defendant knew or should have known of the intoxication. If the intoxication was mild and the person could still understand and choose, consent may still be valid.

Consent given by someone lacking capacity is generally voidable. On an exam, focus on whether a reasonable person in the defendant’s position would realize that the plaintiff could not appreciate the nature of the act.

Scope of Consent

The defendant's conduct must not exceed the scope of the consent given by the plaintiff. Consent is tied to:

• The specific act or acts.
• The time, place, and manner of performance.
• The level of risk reasonably understood by the plaintiff.

Key Term: Scope of Consent
The range of conduct, in terms of type, extent, time, and manner, that a reasonable person would understand as permitted by the plaintiff’s words or conduct.

Key points:

• Consenting to a minor touching does not constitute consent to a more invasive one.
• Consenting to one procedure does not automatically authorize unrelated procedures.
• Role changes matter: consenting to a doctor’s examination does not permit a non-medical stranger to touch you simply because the doctor may do so.

Examples:

• Consenting to a medical examination does not constitute consent to surgery.
• Consenting to play touch football does not constitute consent to being tackled aggressively in a manner outside the understood rules of the game.
• Consenting to a tattoo on your arm does not imply consent to the artist tattooing your neck.

Consent can be conditional. If the defendant knowingly violates a condition, they exceed the scope of consent.

• Example: “You can borrow my car, but do not leave the city.” Driving it across the country exceeds the scope of consent and can support liability for trespass to chattels or conversion.

Revocation of Consent

Consent is not irrevocable. A plaintiff can withdraw consent at any time, even in the middle of an encounter.

Key Term: Revocation of Consent
The plaintiff’s withdrawal of previously given consent, communicated in a way that would lead a reasonable person to understand that consent has ended.

After revocation:

• Any further contact or confinement is unauthorized and can be tortious.
• Revocation must be communicated, if reasonably possible (e.g., saying “stop,” pushing away, or leaving the area).

Example: During a consensual fight or sexual encounter, if one party says “stop” and the other continues, any subsequent contact is outside the scope of consent.

Consent Must Be Voluntary

Consent must be freely and voluntarily given. It is invalidated if obtained through fraud, duress, or certain types of mistake.

Key Term: Fraud (in Consent)
A misrepresentation or concealment by the defendant that induces the plaintiff to consent, where the deceit concerns an essential aspect of the transaction.

Key Term: Duress (in Consent)
Coercion that overbears the plaintiff’s will, such as threats of imminent physical harm, making the plaintiff’s apparent consent involuntary.

Key Term: Mistake (in Consent)
A misunderstanding by the plaintiff about a fact relating to the consented-to conduct that may render consent invalid if the defendant caused or knowingly exploited the mistake.

Fraud

Consent induced by a substantial misrepresentation concerning the nature or consequences of the defendant's conduct is invalid. Fraud must generally go to an essential matter, not a collateral one.

• Essential matters: the very nature of the act or the serious risks involved.

  • Example: A physician falsely tells a patient that a procedure is non-invasive when it carries a high risk of major surgery and serious complications; consent may be invalid.
  • Example: A person lies about being a licensed doctor and then performs a procedure; consent is typically invalid because the fraud concerns the essential nature and safety of the act.

• Collateral matters: background or ancillary details that do not change the basic nature of the act.

  • Example: Consent to intercourse based on a false promise of marriage is usually not considered fraud going to an essential matter for battery purposes.
  • Example: Exaggerating income or social status to obtain consent to a date or kiss normally does not vitiate consent.

A common exam angle is distinguishing between fraud in the nature of the act (invalidates consent) and fraud in a motive or collateral detail (does not).

Duress

Consent given under physical threat or other improper coercion is not valid. Classic duress involves threats of immediate bodily harm.

• Threats of immediate violence (“Let me in or I will break your arm right now”) that induce “consent” to entry or touching invalidate consent.
• Threats of purely economic harm or future harm may or may not amount to duress in tort; this is more often addressed in contract law. The MBE tends to focus on threats of physical harm.

Mistake

If the plaintiff consents based on a mistake concerning the nature or harmfulness of the defendant's conduct, the effect of that mistake depends on the defendant’s role:

• Defendant caused the mistake or knows of it and takes advantage of it:
  Consent is ineffective.
• Defendant is unaware of the mistake and did not cause it:
  Consent is generally still valid.

This aligns with the rule:

• Consent by mistake is a valid defense unless the defendant caused the mistake or knew of it and exploited it.

If the mistake is itself created by the defendant’s misrepresentation, the situation falls under fraud rather than “pure mistake.”

Specific Contexts

Medical Treatment

Generally, medical treatment requires the patient's consent. Treating a patient without any consent can be a battery because any unauthorized medical touching is an offensive contact, even if performed skillfully and beneficially.

Key Term: Informed Consent
A patient's agreement to a medical intervention based on disclosure of the nature of the procedure, its material risks, reasonable alternatives, and the likely consequences of declining treatment.

Two main liability theories arise in medical cases:

• Battery (no real consent):

  • When the doctor performs a completely different procedure from the one to which the patient agreed.
  • When the doctor performs any procedure without consent at all (outside emergencies).
  • When consent was obtained by fraud going to the nature of the procedure.

• Negligence (lack of informed consent):

  • When the patient agreed to the general procedure, but the doctor failed to disclose material risks or alternatives.
  • Most modern cases involving inadequate disclosure sound in negligence, not battery.

Exam tips:

• If the patient consented to “an appendectomy” but the surgeon instead performed a gallbladder removal, that is likely battery.
• If the patient consented to an appendectomy but was not told of a low but serious risk of nerve damage, and that risk materializes, the issue is normally negligence for lack of informed consent, not battery.

Emergency Exception (Implied Consent by Law)

In an emergency where the patient is unable to consent (e.g., unconscious) and treatment is necessary to prevent death or serious bodily harm, consent is implied by law if:

• A reasonable person would consent under the circumstances.
• There is no reason to believe the patient would refuse (e.g., no known religious objection; no Do Not Resuscitate order).
• There is no practical opportunity to obtain consent from the patient or a legally authorized surrogate in time.

Key Term: Emergency Doctrine (Torts)
The principle that in urgent, life-threatening situations where a patient cannot consent, the law implies consent to necessary treatment that a reasonable person would accept.

If a competent patient has previously refused a specific treatment (for example, a documented refusal of blood transfusions for religious reasons), the emergency doctrine does not permit that treatment.

Worked Example 1.1

Scenario: Paul agrees to participate in a friendly game of flag football organized by his colleagues. During the game, Dave, known for overly aggressive play, tackles Paul forcefully from behind, long after the play is over, causing a serious knee injury. Paul did not see Dave coming. Paul sues Dave for battery.

Question: Is Paul's consent to playing flag football a valid defense for Dave?

Answer:
Likely no. While Paul consented to the normal contacts associated with flag football, Dave's conduct (a forceful tackle from behind, long after the play) likely exceeded the scope of that consent. Participants in sports consent to contacts within the rules and customs of the game, not to intentional or reckless conduct beyond those boundaries. Dave's aggressive act outside the context of play negates Paul's implied consent.

Athletic Contests

Participants in athletic contests generally consent to the normal contacts natural to the sport. This includes:

• Contact permitted by the rules.
• Minor or common rule violations that are foreseeable aspects of play (e.g., routine fouls in basketball).

Key Term: Athletic Consent
Consent implied from participation in a sport or game, extending to contacts and risks customarily associated with the activity, but not to conduct outside the bounds of ordinary play.

However, consent does not extend to:

• Conduct completely outside the scope of ordinary play, such as intentional attacks unrelated to game action.
• Conduct demonstrating reckless disregard for a player's safety (e.g., a deliberate blindside punch during a stoppage in play).

A player who intentionally injures another in a way far beyond what the game permits may be liable for battery despite the general consent to participate.

Worked Example 1.2

Scenario: Patient undergoes surgery for appendicitis. During the operation, the Surgeon notices a suspicious mole on Patient's abdomen, unrelated to the appendicitis. Believing it might be cancerous and wanting to save Patient a future procedure, Surgeon removes the mole without prior discussion or consent specifically for the mole removal. Patient had signed a general consent form for the appendectomy.

Question: Can Patient successfully sue Surgeon for battery regarding the mole removal?

Answer:
Yes, likely. The general consent for the appendectomy did not extend to the unrelated removal of the mole. Unless the mole presented an immediate, serious threat discovered during the appendectomy (qualifying as an emergency), its removal exceeded the scope of the consent given. The surgeon needed specific consent for this separate procedure. The emergency doctrine would not apply if the mole did not require immediate treatment to prevent serious harm.

Worked Example 1.3

Scenario: A martial arts studio advertises full-contact sparring. Student signs a waiver acknowledging risk of bruises and minor injuries. During sparring, Instructor becomes angry at Student, who has stopped sparring and is standing relaxed. Instructor suddenly kicks Student in the head with full force, after the session is supposed to be over, causing a concussion. Student sues Instructor for battery.

Question: Can Instructor successfully assert consent as a defense?

Answer:
Probably not. By joining the full-contact class and signing the waiver, Student consented to contacts and injuries arising from normal sparring within the rules and time of the class. Instructor’s retaliatory kick after sparring had ceased and while Student was not participating went beyond the scope of that consent and appears intentional and reckless, not part of ordinary play. Consent to full-contact sparring does not cover an unexpected attack outside the structured activity.

Mutual Combat and Consent

Sometimes both parties voluntarily agree to fight (“mutual combat”). Whether consent is a defense in such cases varies.

Key Term: Mutual Combat
A situation in which two or more persons voluntarily agree to engage in a physical fight.

Key rules:

• Many jurisdictions allow consent as a defense to simple batteries arising from mutual combat, particularly if the fight is minor and not seriously injurious.
• Some courts, however, refuse to recognize consent to serious bodily harm as valid on public policy grounds, especially when the fight is illegal (e.g., street fights, unlicensed prize fighting).
• Even where mutual combat is recognized, the defense is usually limited; using weapons or inflicting severe injuries may exceed any implied consent.

On the MBE, focus on whether the fact pattern suggests agreement to a relatively limited fight, and whether the defendant escalated the violence beyond that agreement.

Consent and Illegal Acts

An additional point: can a person consent to an act that is itself criminal?

• In many jurisdictions, a plaintiff’s consent to criminal conduct (e.g., a consensual but illegal prize fight) is still effective as a defense to an intentional tort claim, unless a statute or strong public policy provides otherwise.
• In some jurisdictions, consent to unlawful conduct is ineffective; a person cannot legally agree to be the victim of a crime, so consent is ignored in tort.

The MBE rarely tests this split directly. If tested, the fact pattern often includes cues such as a statute making the conduct specifically non-consentable (e.g., statutory rape).

Third-Party and Substituted Consent

Sometimes someone other than the plaintiff purports to consent on the plaintiff’s behalf.

Common situations:

• Parents or guardians may consent to many medical treatments and activities for minors.
• Legal guardians or conservators may consent on behalf of mentally incompetent adults.
• For adults who are unconscious or otherwise unable to consent, hospitals may follow statutory hierarchies of surrogates (spouse, adult child, etc.) where no prior directive exists.

On a torts exam, unless the problem turns on medical law detail, assume:

• Properly authorized surrogates can give valid consent to treatment.
• A stranger or unrelated person cannot consent to serious invasions of another adult’s bodily integrity.

Exam Warning

Distinguish carefully between consent implied by conduct (objective indication of willingness based on actions) and consent implied by law (based on emergency situations where plaintiff cannot consent). Also, remember that consent is invalidated by fraud only if the fraud relates to an essential aspect of the interaction, not a collateral matter.

Revision Tip

When analyzing consent, ask systematically:

1. Did the plaintiff have capacity?
2. Did the plaintiff manifest consent (expressly or impliedly)?
3. What was the scope of that consent (type of conduct, time, manner, risks)?
4. Was the consent revoked before the conduct occurred?
5. Was the consent vitiated by fraud, duress, mistake, or public policy/illegality?

Applying this checklist helps structure answers to MBE questions and essays involving consent.

Summary

Consent is a defense that negates the wrongfulness of an intentional tort. It requires the plaintiff's voluntary agreement to the defendant's conduct, evaluated under an objective standard. Consent can be express or implied (from conduct or by law). Valid consent requires capacity and must be voluntary (not induced by fraud, duress, or material mistake known to defendant). The defendant's act must remain within the scope of the consent granted and must cease once consent is revoked.

In medical settings, informed consent is typically required, though emergencies create an exception through consent implied by law. In sports and mutual combat, participants consent to contacts usual to the activity but not to conduct outside its scope or to intentional or reckless escalations. Public policy may limit consent to serious bodily harm or unlawful acts.

Key Point Checklist

This article has covered the following key knowledge points:

• Consent is a defense to most intentional torts and is assessed objectively.
• Consent can be express, implied by conduct, or implied by law in emergencies.
• Valid consent requires that the plaintiff have capacity (age, mental state, sobriety sufficient to understand the act).
• The defendant’s conduct must not exceed the scope of consent in type, extent, time, or manner.
• Consent can be revoked; conduct after revocation is unauthorized.
• Consent obtained through fraud as to essential matters, duress, or certain mistakes is invalid.
• In medical treatment, failure to obtain any consent may be battery; lack of adequate disclosure usually raises negligence (informed consent) issues.
• In athletics, participants consent to ordinary and foreseeable contact within the sport, but not to intentional attacks or reckless conduct unrelated to play.
• Mutual combat may support a consent defense to minor batteries, but public policy and illegality can limit this defense.

Key Terms and Concepts

• Consent
• Express Consent
• Implied Consent
• Implied Consent by Law
• Capacity to Consent
• Scope of Consent
• Revocation of Consent
• Fraud (in Consent)
• Duress (in Consent)
• Mistake (in Consent)
• Informed Consent
• Emergency Doctrine (Torts)
• Athletic Consent
• Mutual Combat