INSANITY. Technically. in law, a disease or disturbance of the mental faculties which may produee some effect on the legal character or quality of the insane person's acts. It may or may not render him non ram poR men I is, that is, subject to legal restraint or control of biz person and property. It may thus be distinguished from lunacy, which may be de scribed as such mental unsoundness as to in capacitate the insane person for all legal trans actions and justify the State through the proper agency in taking charge of his person and prop erty. The discussion of the legal control of the person and property of lunatics, or those who are non compos mentis, is reserved for the article on LUNACY. The law takes cognizance of insane persons as such, chiefly for the following pur poses: (I) To aseertain their responsibility for crime; (2) to a•eertain their •apa•ity to make contracts; (3) to ascertain their liability for torts; (4) to :i•certain their capacity to make wil IS.
t I) IZEseoNsimury eon Cm :OF:. The illSallity Of one charged with crinie may preellide the exist ence of the eriminal intent which is an essential clement of the crime. When, therefore• the plea of insanity is set up on behalf of one charged with crime the question raised is, \\ as the accused capable of forming a criminal intent at the time he committed the (let f The law on this subject Was first fully illve,tigated, and a legal test of insanity in criminal cases adopted, in ,\PNagliton's ease by the English House of Lords in 1843. Al'Nagliton, having killed an other while under the influence of an insane de lusion, was charged with murder and certain questions growing out of the ((age were put to the judges of the House of Lords. They an swered in substance that mere wins not a defense; that to establish want of eriminal responsibility it must be proved that the party accused was laboring under such defect of reason from disease of the mind as not to know the nature and finality of the act he 'W.11,4 doing; that an insane delusion would not establish want of responsibility unless the delusion if trite would justify the defendant in doing the act with which he is charged. Thus, one who killed nuother under nn insane delusion that the other was threatening his life under eiremnstanees of immediate din to himself is not eriminally responsible for the homicide; but an insane de lusion that another was slandering the defendant would not excuse him for killing or (Weil BAST1111t mg the supposed slanderer. assuming always that
in other particulars the defendant knew the na ture and quality of his net. INPNagliton's ease still represents the law in England, and its rules have been adopted by the courts of most of the United States.
The elTect of APNaplitnn's ease is to hold to full legal responsibility one \elm commits an offense under the inthienee of an insane. irresis tible impulse. if lie knew at the time the nature and diameter of his net. And this is generally the law. although it is eonceded that there can he no criminal net without a free agent, and there may be in a given ease the strongest evidenee of the existence of such an impulse. The courts of a few `antes, however, relying on the assertion of medical experts that such a form of insanity does exist, reeognize such a plea as a good ground of defense. but hedge about their ruling with the most stringent requirements as to proof of such mental defect. Idiocy or imbecility is also a defense to crime. The test adopted, viz. that one must have as much mental capacity as a child fourteen years old in order to lie convicted of crime, is not very satisfactor:•, but is probably the best possible. So-called moral insanity and emotional insanity have never been recognized by the courts as a legal defense to crime.
(Inv (-barged with a crime is presumed to he sane, and the prosecution is not in the first in stanee required to introduce evidence of sanity of the defendant. Upon the defendant's offering evi dence to prove his insanity the burden of proving sanity is thrown upon the prosecution. Theoreti cally, since the effect of insanity is to show idisenee of criminal intent, the prosecution should be required to prove beyond a reasonabk dmila in to establish criminal' intent. In a few Stara this is the rule. In the majority, however, the defendant is required to prow his 111,a1lity by the preponderance of t`Videllee, /11111 in one or two to prove his insanity. humid a reasonable doubt. Insanity may also be a bar to the trial or punishment of one eharged with a crime. The test of insanity in the one case is the defendant's ability to understand the na ture of the charge and of the trial. and in the other the nature and purpose of the punishment.