Discuss the historical development of the insanity defense beginning with the 1843 M'Naghten Rule in England and noting the findings of the American Law Institute in the 1960s. In your discussion, define mens rea and the concept of "diminished capacity."

What will be an ideal response?

Daniel M'Naughten was a paranoid schizophrenic who believed that the English Tory party was persecuting him. Consequently, he attempted to kill the British prime minister, but instead killed his secretary. He was tried, but the court ruled that he was not responsible for his behavior because he didn't know what he was doing or that it was wrong. This became the basis of the insanity plea. Over time, questions have been raised about the validity of focusing only on knowledge of right and wrong, so the American Law Institute recommended that people with mental illness who committed crimes should be treated for their disease, not punished. However, highly publicized cases of people who committed murder and claimed insanity in the news have caused some states to move to using a "guilty but mentally ill" distinction, meaning the person is first treated and then punished.