## Facts

- William McDonald was employed as a streetcar driver and conductor.
- A passenger boarded the streetcar and, in fact, paid the required fare.
- McDonald honestly believed that the passenger had not paid.
- McDonald demanded that the passenger pay; the passenger refused to pay again, insisting he had already paid.
- Acting on his belief that the passenger was riding without paying, McDonald forcibly removed the passenger from the streetcar.
- The State charged McDonald with criminal assault and battery based on the physical force used during the removal.
- At trial, the court instructed the jury in substance that the passenger was entitled to ride peacefully because he had actually paid, without regard to what McDonald believed.
- The jury convicted McDonald of assault and battery, and he appealed.

## Issues

1. Whether a streetcar conductor who is allowed to remove nonpaying riders may be convicted of criminal assault and battery for ejecting a passenger who actually paid, when the conductor acted under an honest (and reasonable) mistake of fact that the fare had not been paid.
2. Whether the trial court erred by instructing the jury to treat actual payment as controlling and to disregard the defendant’s good-faith belief about nonpayment when determining criminal liability.

## Decision

- The Missouri Court of Appeals reversed the conviction and remanded for further proceedings.
- The court held that the jury should have been allowed to consider whether McDonald acted under an honest (and reasonable) mistake of fact that, if true, would have placed his conduct within his authority to eject a nonpaying passenger.
- The challenged instruction was erroneous because it allowed conviction even if McDonald acted without a wrongful intent—i.e., even if he believed he was doing what the law permitted.

## Legal Principles

- Criminal assault and battery requires unlawful conduct accompanied by the required mental state; the State must prove more than the mere use of force.
- A mistake of fact may defeat criminal liability when it negates the mental state required for the offense—especially where, if the facts were as the defendant believed them to be, the act would have been lawful.
- When a person has authority to use reasonable force only upon certain facts (such as nonpayment of fare), an honest (and reasonable) belief that those facts exist can prevent the act from being criminal, even if the belief is mistaken.
- Jury instructions are improper when they remove from the jury a legally material question about the defendant’s belief and intent and instead make liability turn solely on the true state of facts.

## Conclusion

State v. McDonald holds that a conductor’s honest (and reasonable) mistake about a passenger’s nonpayment can defeat the mens rea needed for criminal assault and battery where the conductor was acting under a claimed right to eject nonpaying riders; because the trial court instructed the jury to ignore McDonald’s belief and focus only on the passenger’s actual payment, the conviction was reversed and the case was remanded.


State v. McDonald, 7. Mo. App. 510 (1879)