Act, culpability, and causation
Criminal liability ordinarily requires a voluntary act or qualifying omission, the prescribed culpability, concurrence, and causation when a result is an element.
Open the full module →Black-letter propositions
- A voluntary movement or knowingly retained possession can satisfy the act requirement; status alone cannot.
- An omission is punishable only when a legal duty, knowledge, and ability to act exist.
- Model Penal Code culpability descends from purposely to knowingly, recklessly, and negligently; common-law offenses use their stated mental states.
- Transferred intent can move an intended harm to an unintended victim for qualifying offenses.
- Result crimes require actual and proximate causation; an unforeseeable superseding intervention can break the chain.
Attack sequence
1Match a mental state to every material element.
2Find a voluntary act or legal duty to act.
3Confirm concurrence.
4For result crimes, prove actual and proximate cause.
Traps and exceptions
!Strict liability must be clearly indicated.
!Ordinary medical negligence usually does not supersede a violent actor's causation.
!A factual mistake matters only if it negates the required mental state.
A parent able to call for help knowingly leaves a dependent infant in medical distress, and the infant dies.
A parent has a legal duty to protect the child, so the omission can be the actus reus. The prosecution must still prove the required culpability and that timely aid would have prevented death.
Essay-ready formulationCriminal liability requires a voluntary act or duty-based omission accompanied by the prescribed mental state and, for a result crime, legal causation.