Insanity defense

In criminal trials, the insanity defense is the lawyer  saying that someone accused of a crime is not guilty for his or her crimes because of a mental illness. People who have been found to be insane have been let out of full criminal punishment since the Code of Hammurabi.Fletcher, G. (1998) Basic Concepts of Criminal Law. NY: Oxford Univ. Press. There are different definitions of legal insanity in different places.Philip Cowen; Paul Harrison; Tom Burns, Shorter Oxford Textbook of Psychiatry (Oxford: Oxford University Press, 2012), p. 723 An insane defendant is usually put in a mental health facility instead of a prison. 

 M’Naghten 
In the 1840s, a Scottish man named Daniel M’Naghten shot and killed Sir Robert Peel’s secretary Edward Drummond and was found not guilty by reason of Insanity. The court said that a criminal is “not guilty by the grounds of insanity” if the person has a mental illness that makes it impossible to know what he did or that makes it impossible for him to know that what he did was bad. This is called the M’Naghten rule. The M’Naughten rule is used in a lot of countries with Common law. 

 Temporary Insanity 

When the defendant is not insane now but was insane when he committed his crimes, it’s called temporary insanity. The first to use this defense was Daniel Sickles when he killed his wife's lover Francis Barton Key (son of Francis Scott Key) in 1859.

 Application 

In the United Kingdom, Ireland, and the United States, the insanity defense is not used much. But, in the United Kingdom, people have been using it more.RD Mackay, BJ Mitchell, L Howe (2006) 'Yet more facts about the insanity defense' Criminal Law Review 399-411  Mitigating factors, including things not eligible for the insanity defense like being drunkAmerican Psychiatric Association: The Insanity Defense: Position Statement. Washington, DC: APA Document Reference No. 820002, 1982 (or, more frequently, diminished capacity), may lead to reduced charges or a shorter prison sentence. 

The question of who has to prove what is an issue in the United States. Before the John Hinckley, Jr. trial, it was the government in most states. After that, many of these states decided that the criminal’s lawyers had to prove that he was legally insane. Where the state still bears the burden of proof, the standard for the prosecution is beyond a reasonable doubt. Where the defense bears the burden, the standard is preponderance of the evidence (a lower standard).

 Expert testimony 
The insanity defense is based on evaluations by forensic mental health professionals with the appropriate test according to the jurisdiction. Their testimony guides the jury (or judge in a bench trial). But they may not testify to the defendant's criminal responsibility. This is for the jury or judge to decide. Mental health experts may testify as to whether at the time of the crime the defendant understood what he did was wrong. If the defendant were acting under a delusion at the time and could still determine right from wrong, he is not insane and may be punished. 

 References 

 Other websites 
 Insanity Defense - Insanity defense statistics, Problems with NGRI, Guilty but mentally ill
 Other Notorious Insanity Cases
Category:Mental health law
Category:Criminal justice