Everyone agrees that mens rea is relevant to fault. The maxim actus non fit reus nisi mens sit rea has been around for centuries.1 According to foundational principles of the criminal law, it is normally not enough to support a conviction that D perpetrates the actus reus. Neither should it be. Causing harm to another person may be unfortunate, but the moral turpitude associated with a criminal conviction requires some element of fault. And to show that, we need mens rea