A man walking on a public street is struck by a rock thrown by a mentally ill boy who suffers from hallucinations. In a suit against the boy for battery, what is the boy’s best defense?

• A. The boy did not understand that his act was wrongful.
• B. The boy did not want to cause harm to the man.
• C. The boy did not know that he was striking a person.
• D. The boy thought the man was about to attack him.

Answer: (C)

The key idea is that battery requires intent to cause harmful or offensive contact, or at least knowledge that contact is substantially certain to result. When someone has a mental illness that prevents forming that intent, liability can fail because the necessary mental state isn’t present. Here, the boy’s hallucinations mean he may not have known that his rock would strike a person. If he didn’t know he was striking a person, he may lack the required intent to contact the man, which is the essential element of battery. The other options don’t fit as cleanly: wanting to avoid harming or not recognizing the act as wrongful aren’t the controlling factors for intent in battery, and a self-defense story would require a reasonable belief of imminent danger, which isn’t established here.