{"id":352282,"date":"2023-08-30T15:11:52","date_gmt":"2023-08-30T20:11:52","guid":{"rendered":"https:\/\/content.findlaw-admin.com\/ability-law\/criminal\/criminal-procedure\/insanity-defense.html"},"modified":"2023-08-30T15:11:52","modified_gmt":"2023-08-30T20:11:52","slug":"insanity-defense","status":"publish","type":"page","link":"https:\/\/www.findlaw.com\/criminal\/criminal-procedure\/insanity-defense.html","title":{"rendered":"Insanity Defense"},"content":{"rendered":"\n
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What Is The Insanity Defense?<\/h1>\n
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\n By Linda Sanabria, J.D.<\/a> | Legally reviewed by Melissa Bender, Esq.<\/a>\n | Last reviewed\n
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This article has been written and reviewed for legal accuracy, clarity, and style by FindLaw\u2019s team of legal writers and attorneys<\/a> and in accordance with our editorial standards<\/a>.<\/em><\/p>\n\n <\/div>\n <\/details>\n\n

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The last updated date refers to the last time this article was reviewed by FindLaw or one of our contributing authors<\/a>. We make every effort to keep our articles updated. For information regarding a specific legal issue affecting you, please contact an attorney in your area<\/a>.<\/em><\/p>\n\n <\/div>\n <\/details>\n<\/section>\n

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By using the insanity defense, a criminal defendant is telling the court that they may have committed the crime of which they are accused. But they’re claiming they shouldn’t be held responsible because of a severe mental health condition. The insanity defense is unrelated to a defendant’s current mental health. Rather, it applies to their mental state at the time of the crime.<\/p>\n\n <\/div>\n\n

The insanity defense<\/a> is an affirmative defense<\/a> against criminal charges. You may have heard of someone being found not guilty by reason of insanity.<\/p>\r\n

This defense is often confused with diminished capacity<\/a>. However, diminished capacity is not an affirmative defense that allows someone to plead not guilty in a criminal trial. Instead, the defendant may plead to a lesser crime based on their mental capacity because they were not capable of having the intent to commit the original crime with which they were charged.<\/p>\r\n

The insanity defense is also different from competency<\/a> to stand trial. If someone cannot understand the charges being brought against them, they cannot be tried at all.<\/p>\r\n

Wondering how courts test for insanity? Unsure of state law differences or which cases have used the insanity plea? Read on for basic information and legal issues related to the insanity defense and criminal responsibility.<\/p>\r\n

Background<\/h2>\r\n

An English legal treatise from 1581 first records insanity as a defense to criminal charges<\/a>. The treatise stated that "a madman or a natural fool, or a lunatic in the time of his lunacy" could not be culpable for killing someone.<\/p>\r\n

Two centuries later, British courts came up with the "wild beast" test<\/a>. A defendant who could not understand their actions any more than an "infant, brute, or wild beast" would not be culpable for their crimes. In other words, the defendant would be found not guilty by reason of insanity.<\/p>\r\n

While the terms "lunatic" or "wild beast" have fallen from use, current laws that allow the insanity defense<\/a> follow a similar logic. As a result, the legal basis for insanity was codified into British law in the mid-19th century.<\/p>\r\n

The M’Naghten Rule (sometimes spelled as M’Naughten) was also codified. This rule was created based on the case of Daniel M’Naghten. The Scottish woodcutter killed the secretary of the British prime minister under the belief that he was conspiring against M’Naghten.<\/p>\r\n

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