Also known as: insane · insanities · insanity defense · NGRI
Written by attorneys · grounded in primary & secondary sources — see below
A legal standard of mental incapacity that excuses a person from criminal or civil responsibility when a severe mental disorder prevents appreciation of wrongfulness or conformity of conduct to law.
Igor Ito, an adult with a documented psychotic disorder, bypassed a mandatory safety test at his manufacturing plant to meet a deadline. The vessel ruptured and injured a neighboring business. Igor is liable for negligence because his mental condition supplies no defense under the governing standard of care.
Ingrid Innes remained silent after receiving Miranda warnings during questioning about sabotage charges. At trial she raised an insanity defense. The prosecutor may not argue that her post-warning silence demonstrates she appreciated the wrongfulness of her conduct.
Select any source to read its text and confirm it supports the definition.
Ibrahim Iqbal filed a written notice of an insanity defense only after discovery closed and after receiving an unfavorable plea offer. The court may preclude the defense because the notice was untimely and no good cause for late filing appears.
Iain Irons, an adult with documented mental illness, walked into traffic without looking and was struck by a vehicle. His contributory negligence claim does not fail on that ground because, as an insane person, the standard for his own protection is not that of a reasonable person under like circumstances.
Imran Iyer killed a coworker and asserted insanity at trial. The prosecution proved every element of murder beyond a reasonable doubt. Imran bears the burden of proving by a preponderance that his mental disease or defect excused responsibility.
Irene Ingalls stabbed a colleague while suffering from borderline mental deficiency and psychopathic tendencies. She conceded the evidence did not establish full insanity. The jury may still consider that evidence when deciding whether she acted with the deliberation required for first-degree murder.
No. Unless the actor is a child, insanity or other mental deficiency does not relieve the actor from liability for conduct that fails to conform to the standard of a reasonable person under like circumstances.
No. Once Miranda warnings are given, the implicit assurance that silence carries no penalty forbids the prosecution from using the defendant's post-warning silence as evidence to rebut or counter an insanity defense.
The defendant cannot rely on the insanity defense. Written notice must be filed within the time for pretrial motions or at a later time set by the court. Failure to comply bars the defense absent a showing of good cause for late filing.
Unless the actor is a child or an insane person, the standard of conduct to which he must conform for his own protection is that of a reasonable person under like circumstances.
The defendant bears the burden of proving the affirmative defense of insanity. The prosecution retains the burden of proving every element of the offense beyond a reasonable doubt.
…Eriswell was not a criminal case at all, but a Crown suit against the inhabitants of a town to charge them with care of an insane pauper. Id. , at 707-708, 100 Eng. Rep., at 815-816. It is relevant only because the judges discuss the Marian statutes in dicta. One of them, Buller, J., defended admission of the…