Master A passenger’s conduct implied consent to a smallpox vaccination, defeating a battery claim. with this comprehensive case brief.
O'Brien v. Cunard is a foundational torts case on consent, illustrating the objective approach to evaluating whether a plaintiff consented to bodily contact. The court held that consent need not be express; it can be inferred from a person’s outward behavior and the circumstances. In doing so, the case teaches that a defendant may rely on reasonable appearances—what a reasonable person in the actor’s position would understand as consent—rather than the plaintiff’s undisclosed, subjective intent.
The decision also sits at the intersection of tort law and public health practice. The vaccination occurred in the context of immigration screening for smallpox, where passengers were informed that vaccination or proof thereof was a condition of landing. O'Brien underscores how legal rules about bodily autonomy and personhood are operationalized through consent doctrine, and it anticipates later debates about medical battery, informed consent, and the boundary between public health regulation and individual rights.
154 Mass. 272, 28 N.E. 266 (Mass. 1891)
The plaintiff, O’Brien, was a passenger aboard a Cunard steamship traveling to the United States at a time when immigration authorities required arriving passengers to be vaccinated against smallpox or to present satisfactory proof of prior vaccination to be permitted to land. As the ship neared port, the defendant’s ship’s surgeon vaccinated passengers on board. Notices were posted or announcements made explaining the requirement, and an interpreter was available. O’Brien joined the line of passengers waiting to be vaccinated, approached the surgeon when it was her turn, and held out (or up) her arm. She neither withdrew her arm nor voiced an objection during the procedure. Although she later asserted she had previously been vaccinated and attempted to say so, she did not refuse the vaccination or remove herself from the line. Afterward, she experienced ill effects and sued the steamship company for assault and battery, contending she had not consented to the vaccination and that the company was liable for the surgeon’s act.
Whether a passenger’s outward conduct—standing in line for vaccination and holding out her arm—objectively manifested consent such that a reasonable person in the surgeon’s position would understand she consented, thereby defeating a battery claim.
Consent to bodily contact may be express or implied and is determined objectively from the plaintiff’s overt acts and the surrounding circumstances, not the plaintiff’s unexpressed intentions. If the plaintiff’s conduct would lead a reasonable person in the actor’s position to believe consent was given, the contact is privileged and not a battery.
Yes. The plaintiff’s conduct objectively indicated consent to the vaccination; therefore, the surgeon’s act was not a battery, and the steamship company was not liable.
The court emphasized that consent is a question of outward manifestation judged by an objective standard. The setting made the stakes clear: passengers were informed that vaccination (or satisfactory proof of prior vaccination) was a condition of landing. In this context, the ship’s surgeon vaccinated passengers who presented themselves in line. O’Brien voluntarily joined that line, presented herself at the front, and held out her arm. She did not object, withdraw, or otherwise indicate unwillingness when the vaccine was administered. Even if she internally preferred not to be vaccinated or had previously been vaccinated, her external behavior reasonably conveyed assent to the surgeon. The court reasoned that the surgeon was entitled to rely on what a reasonable observer would take from O’Brien’s conduct—overt acquiescence to the procedure—particularly where an interpreter was available and nothing in her behavior signaled dissent. Because the act was consented to, it was privileged and not a wrongful touching; without an underlying tort, the employer could not be held liable. The court thus rejected the battery claim and approved the instructions that consent could be implied from conduct.
O’Brien is a staple in first-year Torts for its clear articulation of the objective theory of consent. It teaches that consent is evaluated based on what the defendant reasonably understands from the plaintiff’s words and actions, not the plaintiff’s secret wishes. This has broad implications for intentional torts, medical battery, and everyday interactions, setting a baseline for how consent operates outside of formal agreements. The case also provides a historical reference point for modern doctrines of informed consent: while O’Brien focuses on whether any consent existed (negating battery), contemporary disputes often turn on whether consent was informed (potential negligence). For students, the case clarifies how bodily autonomy is protected through consent doctrine while recognizing that consent can be communicated implicitly through conduct.
No. The case squarely holds that consent can be implied from conduct and context. Standing in line, presenting oneself for treatment, and holding out an arm for a shot are objective manifestations that can reasonably be understood as consent, defeating a battery claim even without verbal assent.
O’Brien addresses whether any consent existed, which negates battery (an intentional tort). Informed consent typically arises in negligence, focusing on whether the physician breached a duty to disclose material risks. A patient may consent in fact (defeating battery) but still claim negligence for inadequate disclosure. O’Brien thus complements, rather than conflicts with, modern informed consent doctrine.
Under O’Brien’s objective standard, undisclosed subjective intent does not control. If the plaintiff’s outward behavior would lead a reasonable person to conclude consent was given, the contact is privileged. The law allocates the burden to the person who does not consent to communicate dissent or refrain from conduct signaling assent.
Likely yes. Clear verbal objection or physical withdrawal would negate reasonable belief in consent. In that scenario, administering the vaccine could constitute a battery absent another legal privilege (e.g., exigency or statutory authority). O’Brien turns on the absence of any outward objection and the presence of conduct indicating agreement.
The context explains why passengers queued and why the surgeon reasonably inferred consent; vaccination was a known condition of landing. While the public health backdrop does not itself create a blanket privilege, it shapes the reasonable person analysis by informing what the parties understood and how consent would typically be manifested in that setting.
O’Brien v. Cunard crystallizes the objective theory of consent in intentional torts. By holding that a plaintiff’s outward conduct—rather than unspoken reservations—controls, the court ensures that consent can be reliably inferred from ordinary social signals and that actors may reasonably rely on what people do and say in context.
For law students, the case is a bridge between the core elements of battery and broader themes of bodily autonomy and personhood. It shows how consent functions as a privilege to otherwise wrongful touchings and foreshadows modern disputes about medical and public health interventions, where the distinction between any consent and informed consent becomes pivotal.