Key Takeaways

  • Consent is an affirmative defense in tort law that can bar liability when the plaintiff agreed to the conduct.
  • The defense requires valid, voluntary, and informed consent; it can be express or implied through conduct.
  • Consent has limits—defendants cannot exceed its scope, and it may be withdrawn at any time.
  • Consent obtained through fraud, coercion, incapacity, or to an unlawful act is often invalid.
  • Special rules apply to minors, incapacitated persons, emergencies, and medical contexts.

Consent

Consent by the injured party can negate the existence of a tort as is apparent in the Latin phrase volenti non fit injuria – to one who is willing, no wrong is done. Consent is judged by its objective manifestation: if a reasonable person would believe that the injured party consented there will be no tort, even if there was no willingness in fact. In certain circumstances silence or inaction will constitute consent.

Even where there is consent, the defendant cannot exceed the scope of the consent. For example, a football player can expect to be tackled and a serious injury may result with no tort; however, if he were tackled during a stop in play or on the sidelines, he would probably have a cause of action against the tackler – the action lay outside the customs of the game and therefore exceeded the scope of consent. Likewise, if the defendant performs a substantially different act than what was consented to, a tort will lie.

Consent can be revoked before the act or even during the act. For example, one could consent to sexual contact and then revoke that consent during the act, and the defendant could be liable for battery if he continues with the contact. Furthermore, consent can be vitiated by an affirmative misrepresentation. So, if the defendant knew or reasonably should have known that the plaintiff was mistaken as to what she was agreeing to, then he can still be guilty of an action. But, the mistake on the plaintiff's part must extend to the “essential character” of the act itself rather than some collateral matter. There are several interesting cases involving consensual sex between a husband and wife where the husband was found guilty of battery for not disclosing STDs contracted in an extramarital affair.

A majority of states also hold that one cannot consent to an illegal act, although a minority of states and the Restatement hold that the consent will defeat a civil action except where the force exceeds the consent. One must also be legally capable of consenting; therefore, an infant or an incapacitated person cannot legally consent (this rule usually extend to intoxicated people as well, though the level of intoxication necessary to vitiate the consent varies). There is one exception to this rule, known as the “emergency exception.” In the emergency exception the person must be unconscious and time must be of the essence. In these situations the court will look at whether a reasonable person would have consented had they been conscious.

Forms of Consent in Tort Law

Consent can be either express or implied, and courts examine the circumstances to determine whether the plaintiff genuinely agreed to the conduct.

  • Express consent occurs when a plaintiff clearly communicates permission, either verbally or in writing. Signing a waiver before a sporting event is an example.
  • Implied consent is inferred from conduct, circumstances, or established customs. For instance, attending a baseball game implies consent to ordinary risks such as foul balls entering the stands.

The distinction matters because implied consent may only extend to risks reasonably associated with an activity, while express consent may provide broader protection if the language is clear.

Limits on Consent

Consent is not unlimited. Even if granted, a defendant cannot exceed its scope. Courts look closely at what the plaintiff agreed to:

  • Scope exceeded: Tackling in football is expected, but a tackle outside the rules of play may fall outside the consented risk.
  • Material difference: If the defendant performs a substantially different act than what was agreed to, consent is invalid.
  • Withdrawal: A plaintiff can revoke consent before or during the act. Continuing after revocation can establish liability.

Additionally, consent obtained through fraud, misrepresentation, or coercion is invalid. For example, concealing a sexually transmitted disease before intercourse undermines the plaintiff’s ability to provide informed consent.

Capacity and Legality of Consent

For consent to serve as an affirmative defense, the plaintiff must have the legal capacity to give it. This means:

  • Minors, intoxicated persons, or individuals with diminished mental capacity often cannot legally consent. Courts assess the level of impairment in each case.
  • Consent to illegal acts is controversial. Most jurisdictions hold that consent to an unlawful act—such as agreeing to participate in an illegal street fight—cannot excuse liability, though some states allow it to bar recovery unless the force used exceeded what was agreed upon.
  • Emergency exception: When someone is unconscious and immediate medical action is necessary, courts presume that a reasonable person would have consented to life-saving treatment.

Consent in Medical and Professional Contexts

Consent plays a central role in medical procedures and professional services. Doctors, for example, must obtain informed consent, meaning the patient understands the nature of the treatment, its risks, and alternatives. Performing a different procedure than what was agreed to may give rise to liability for battery, even if the procedure was beneficial.

Similarly, professionals such as attorneys or therapists must operate within the bounds of client consent. Actions outside that scope, even if well-intentioned, can create liability.

Public Policy and Consent

Courts may refuse to recognize consent in situations where it would violate public policy. For example, one cannot legally consent to serious bodily harm in a street fight, as allowing such consent would undermine public safety. Similarly, consent cannot be used to shield against liability for acts that threaten the broader public interest.

Frequently Asked Questions

  1. What is consent as an affirmative defense in tort law?
    Consent is a defense where the plaintiff’s agreement to the conduct eliminates liability, provided the consent was valid and informed.
  2. Can consent be implied, or must it always be explicit?
    Consent can be either express (spoken or written) or implied through behavior, customs, or circumstances.
  3. When is consent invalid in tort law?
    Consent is invalid if obtained by fraud, coercion, or given by someone without legal capacity (e.g., minors or incapacitated persons).
  4. Can consent be revoked?
    Yes, a person can withdraw consent at any time before or during the act, and continuing afterward may create liability.
  5. Can someone consent to an illegal act?
    Most states reject consent as a defense to unlawful acts, though some allow it unless excessive force is used.

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