O’Brien v. Cunard S.S. Co.

154 Mass. 272, 28 N.E. 266 (1891)

Rule of Law

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Consent is a defense to an assault charge, and the circumstances must be reviewed in each case. Only overt acts or visual indications of consent can be used as evidence.

Facts of the Case

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O’Brien (the plaintiff) was a passenger on the ship bound for Boston. Only those with vaccination certificates were permitted entry into Boston. To avoid quarantine upon arrival, (the defendant) Cunard Steamship Company arranged for its passengers to receive vaccinations.

Soon after receiving the vaccination from the surgeon, O’Brien developed blisters and became ill. As a result, she filed a lawsuit against the defendant for assault, alleging she was forced to receive a vaccination.


Issue Icon

Can one depend on the behavior and apparent actions without clear consent to determine if the other party agreed?

Holding and Conclusion

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According to the presented evidence, the plaintiff did not oppose vaccination. The plaintiff voluntarily and without hesitation received the vaccination on her arm. The judge concluded that the surgeon’s actions were appropriate. There were no indications that the surgeon had been negligent. Even if the defendant were at fault, the court determined it was unreasonable to hold him accountable for every aspect of the surgeon’s care.

Reasoning and Analysis

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It is the responsibility of the jury to determine whether the action occurred within the scope of the consent granted. In this particular case, O’Brien went ahead and offered her arm for vaccination without any hesitations, and as a result, she also obtained the certificate.

This concludes that she was not forced to receive the vaccination and her claim was rejected.

Relevant FAQs of this case

What is considered a valid consent?

Consent is only valid if adequate information is provided to the individual, and if that person is of legal age and mental competence to make such a decision.

However, there are some conditions to that as follows:

  • The individual must feel no pressure to consent, and those close to them should not exert any influence over their decision.
  • The person needs to know everything there is to know about, including its possible benefits and risks, any good alternatives, and what might happen if the person decides not to agree.
  • The individual must have the mental capacity to provide their permission, which means they can take in all of the information presented to them and utilize it to make a deliberate choice.

What is considered an invalid consent?

Following are the situations where consent is considered invalid:

  • When someone is a minor.
  • When someone considers themself in danger and cannot defend themself.
  • A situation where physical force is used.
  • Consent from a person who is mentally disabled.
  • Silence or the absence of resistance alone does not constitute consent. An individual is not required to resist or say “no” to deny permission.


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