Less than one percent of felony cases raise an insanity defense in hopes of nullifying the case. In that one percent, there is even less of a chance that the defense will be successful. (“Frontline”) An insanity defense may not have a high success rate, but when it does succeed, it can get an overwhelming amount of media coverage. One famous case in particular is the trial of Jeffery Dahmer. He pleaded not guilty by reason of insanity, but his plea was later rejected (Murdock & Navasky). Insanity is most well-known as a criminal defense plea, but is also considered to be a lack of mental stability. Many people may not know that there are different types of tests to evaluate the credibility of the defense plea. The insanity defense plea originated in England because of the case …show more content…
(“M’Naghten Rule”). Because of this case, there were multiple different tests set in place to prove if someone was criminally insane. Some states in the United States still use the M’Naghten test, while other states use different tests, such as the Durham Test, the “Irresistible Impulse” test, or the Model Penal Code test (“M'Naghten Rule”). The M’Naghten rule did become the standard for the United Kingdom and, in the United States, for more than half of the states. Some adjustments have been made for the M’Naghten test; these can include any defendant who was initially presumed sane until proven to not have the mental capacity to understand what they had committed or that they knew what they were doing at the time but truly did not believe that it was wrong (“M'Naghten Rule”). Exercising the word of God or believing a prophecy can be examples of thinking that you are right, but in reality, you are committing a crime. There is one major problem with the M’Naghten test: it is not well suited for more subtle forms of psychological