In order for someone to be responsible, or culpable, for a criminal act, it is necessary to have criminal intent. In other words, the person must have intentionally chosen to act in a criminal way. As intention is a psychological state—and one that is not always easy 8 to prove—the individual’s mental state is relevant to the proof of criminal intent. Therefore, someone who is mentally ill, or “insane,” may not have the psychological wherewithal to have criminal intent. Such a person may not understand what he or she is doing, or may not be able to control himself or herself. While most people agree that profoundly mentally ill people should not be held to the same standard of accountability as the rest of the population, it is difficult to tell when mental illness justifiably excuses criminal behavior. Can someone be mentally ill and still culpable? How do we define mental illness?