It is a logical result of the nature of de lusion and its legal relations as shown by these definitions that it will be of no avail as a defence unless, if true, the facts sup posed to exist would have excused the crime; id.; Thurman v. State, 32 Neb. 224, 49 N. W. 338; People v. Taylor, 138 N. Y. 398, 34 N. E. 275 ; Smith v. State, 55 Ark. 259, 18 S. W. 237. This rule is well illustrated by a case in which it was held that an instruc tion that "defendant would not be respon sible if he killed deceased under an insane delusion that deceased was trying to marry defendant's mother, and that this delusion caused the killing," was properly refused ; Bolling v. State, 54 Ark. 588, 16 S. W. 658.
In order that delusion may be a defence it must be connected with the crime, and if a person has an insane delusion upon any one subject, but commits a crime not con nected therewith, he is equally guilty as if he were in all respects sane; State v. Gut, 13 Minn. 341 (Gil. 315) ; Bovard v. State, 30 Miss. 600; State v. Huting, 21 Mo. 464. "A man whose mind squints, unless impelled to crime by this very mental obliquity, is as much amenable to punishment as one whose eye squints." Gibson, C. J., in Coin. v. Mos ier, 4 Pa. 264. See also Alison, Cr. L. 647 ; Ray, Insan. 106, 135, 227 ; 3 Couper 357 ; State v. Simms, 71 Mo. 538; 1 Bish. N. Cr. L. 394.
"Where a defendant is acting under an insane delusion as to circumstances which, if true, would relieve the act from responsi bility, such delusion is a defence ;" Whart. & St. Med. Jur. § 125 ; but such delusions must involve an honest mistake as to the object to which the crime is directed; id. § 127; 3 F. & F. 839. The term delusion as applied to insanity, does not mean a mere mistake of fact, or being induced by false evidence to believe that a fact exists which does not exist ; Middleditch v. Williams, 45 N. J. Eq. 726, 17 Atl. 826, 4 L. R. A. 738.
A disposition to multiply the tests, so as to recognize essential facts in the nature of insanity, has been manifested in this coun try to a much greater extent than in Eng land.
The existence of an irresistible impulse to commit a crime has been recognized in the law ; Steph. Cr. L. 91 ; and medical authorities are generally in agreement that, as it is put by Bishop, "the mental and physical machine may slip the control of its owner ; and so a man may be conscious of what he is doing, and of its criminal character and consequences, while yet he is impelled to it by a power to him irresist ible:" 1 New Cr. L. 387; 3 Witth. & Beck. 270, 275 ; 1 Beck, Med. Jur., 10th ed. 723 ; Ray, Insan., 3d ed. a 17, 18, 22. But the writer last quoted adds : "Whether or not such is truly so must, in the nature of things, be a pure question of fact, it cannot be of law." In England the courts have refused to recognize this ground of exemption from responsibility and limit the test to ability to distinguish between right and wrong; Clarke, Cr. L. 56; 1 Bish. N. Cr. L. § 387;
3 C. & K. 185; 1 F. & F. 666; 3 Cox, C. C. 275.
The American cases are very difficult to classify with reference to this test, as indeed they are on most branches of the subject, nor is such the present purpose; all that is possible being, by reference to a selection of the cases, to illustrate the progress of the law and the direction in which, but not, critically, the precise extent to which, changes have been made since Lord Hale's time, keeping pace with the growth of scien tific knowledge.
A full understanding of the scope of the doctrine now under consideration involves the further subject of power of resistance, which enters largely into this class of cases and is also more particularly referred ,to, In Roger's case, 7 Mete. (Mass.) 500, 41 Am. Dec. 458, the jury were directed to con sider, in addition to the test of right and wrong, whether the prisoner, in committing the homicide, acted from an irresistible and uncontrollable impulse; and this case has been much relied on in American courts ; Ray, Med. Jur. 58.
In Freth's case, 3 Phila. (Pa.) 105, Judge Ludlow charged : "If the prisoner was actuated by an irresistible inclination to kill, and was utterly unable to control his will, or subjugate his intellect, and was not actuated by anger, jealousy, revenge, and kindred evil passions, he is entitled to an accpSittal," etc.
In the leading case of State v. Harrison it was said by Brannon, J.: "This irresist ible-impulse theory test has been only re cently presented, and while it is supported by plausible arguments, it is rather refined, and introduces what seems to me a useless element of distinction for a test, and is mis leading to juries, and fraught with great danger to human life, so much so that even its advocates have warningly said it should be very cautiously applied and only in the clearest cases. What is this irresistible im pulse? How shall we of the courts and juries know it? Does it exist when mani fested in one single instance, as in the pres ent case, or must it be shown to be habitual, or, at least, to have evinced itself in more than a single instance? . . . I admit the existence of irresistible impulse and its efficacy to exonerate from responsibility, but not as consistent with an adequate realiza tion of the wrong of the act. It is that un controllable impulse produced by the disease of the mind, when that disease is sufficient to override judgment and obliterate the sense of right as to the acts done, and deprives the accused of power to choose between them;" 36 W. Va. 729, 15 S. E. 982, 18 I.: R. A. 224.