At common law, a victim had to prove four elements to demonstrate that a crime had occurred: mens rea (the mental element of a crime whereby intent or blameworthiness must be established), actus reus (the physical elements of a crime whereby the actions of a defendant must be established), causation, and damages or harm. This brief post concerns the first element, mens rea.

The concept of means rea involved three kinds of intent at common law: (1) general intent (the wish to do something prohibited by law), (2) specific intent (the wish to do something prohibited by law and to cause a particular result), and (3) transferred intent (which arises when the intention to harm one person results in harm to a different person).

The definition of intent traditionally included not just the results an actor wanted to occur when he contemplated taking some action, but also the results he knew would almost certainly occur from that action even if he did not truly wish to bring them about.

The landmark case of People v. Conley (1989) demonstrated that it was not always necessary, when establishing the elements of a crime, to show that an actor consciously desired the result of a particular harm as long as he knew that his conduct was virtually certain to cause general harm. A prosecutor may accordingly establish the element of intent by showing that a person consciously desired to occasion a particular harm or that he knew that his conduct was practically certain to cause harm.

Under the doctrine of transferred intent, a prosecutor may demonstrate that the defendant committed a crime if he intended to cause harm to one person but accidentally harmed a different person. This principle is also revealed in People v. Conley, in which an individual named William Conley attempted to strike Marty Carroll with a wine bottle but mistakenly struck Sean O’Connell instead. Because Conley attempted to commit a battery and did in fact strike someone as he intended, he was guilty of the crime of battery. The fact that his victim was not his intended victim was immaterial to his case.