power; and this fact cannot justly be ignored in deciding upon his responsibility for criminal acts. Insanity once admitted, it is within the reach of no mortal comprehension to know exactly how far it may have affected the quality of his acts. To say that, possibly, it may have had no effect at all, is not enough. It should be proved by the party who affirms it :" Mandsley on Resp. in Ment. Dis. 111. But this relates to the burden of proof, which we will hereafter consider. Insanity once admitted, in any degree, it is only sheer presumption, not wisdom, to say that it could not have perverted the action of the mind. in regard to any particular criminal act: Ray's Med. Jur. 60-64, 273-284.

§ 46. Doctrine as to the burden of proof.

The English rule as to the burden of proof, on a plea of insanity in a criminal case, is upon the defendant, and he is required to prove his insanity beyond a reasonable doubt. The defense is one of confession and avoidance, and the matter of avoidance must be fully established by the prisoner: 3 C. & K. (Eng.) 188; 4 Cox C. C. (Eng.) 155. And this rule has been fol

lowed in various states in this country: See 21 N. J. L. 202; 76 Pa. St. 414; 8 Jones (N. C.), 463; 36 Am. Rep. 467.

But in most of the states of the Union the general rule seems to be that, whenever in the course of a trial evidence is produced showing that the defendant was of unsound mind at or before the time the criminal act was done, the burden of proof immediately rests upon the prosecution to show the contrary. In such a case the onus shifts upon the prosecution, and it devolves upon that side to show that insanity did not exist, or if it did, that it was not of such a character as to excuse the act: 14 A. L. Reg. N. S. 20; 16 id 453; 40 N. H. 399; 43 id. 224; 19 Ind. 170; 40 Ill. 352: 17 Mich. 9; 10 Fed. Rep. 163, 202; 2 Field's Lawyers' Briefs, § 272; 4 Field's Lawyers' Briefs, §§ 114,

146.

§ 47. General presumption.

The general presumption is in favor of mental soundness, and usually the burden of proof would rest upon the party denying it, whether the question arises upon a contract or will, or upon trial

332, 405; 2 Gr. Pa. St. 441; 47

for a crime. But if a previous state of general insanity is shown, the burden of proof would be changed, and in such a case proof of the sanity of a testator would devolve upon the party affirming it: See Wills, vol. 5, Field's Lawyers' Briefs, § 730; Evidence, vol. 3, Field's Lawyers' Briefs, § 310; Best on Ev., §§ Ev., § 689; Grabill v. Barr, 5 Am. Dec. 418; Rogers v. Walker, 6 Pa. St. 371 ; 47 Am. Dec. 470; Commonwealth v. Rogers, 7 Met. (Mass.) 500; 41 Am. Dec. 458; see also Gerish v. Nason, 22 Me. 438; Cilly v. Cilly, 34 Me. 162; Dean v. Dean, 27 Vt. 746; Gabriel v Barr, 5 Pa. St. 441; 47 Am. Dec. 418; Thomp son v. Kyner, 65 Pa. St. 368; Eckert v. Flowry 43 Pa. St. 56; Trumbull v. Gibbons, 22 N. J. L 117; 51 Am. Dec. 253; Morris v. Stokes, 21 Ga. 552; Taylor v. Kelly, 31 Ala. 59; Colton v. Ulmer, 45 Ala. 378; Chandler v. Barrett, 21 La. An. 58; Guthrie v. Pierce, 33 Ark. 396; Matter of Coffman, 12 Ia. 491; McIntyre v. McCown, 28 Ia. 480; Roe v. Taylor, 45 Ill. 485; Rutherford v. Morris, 77 Ill. 397; Harvey v Sullens, 46 Mo. 157; People v. Meyers, 20 Cal· 520.

The rule as to the quantum of evidence to establish insanity as a defense in criminal cases is the same as in civil cases, viz.: that the jury may determine the question from a mere preponder. ance of evidence; and proof that such a mental condition existed beyond a reasonable doubt does not seem to be required: State v. Lawrence, 57 Me. 574; Com. v. Rogers, 7 Met. (Mass.) 500; Com. v. Eddy, 7 Gray (Mass.), 183; Ferris v. People, 35 N. Y. 125; Hoifs v. People, 31 Ill. 385; State v. Felter, 32 Ia. 50; State v. Hundley, 46 Mo. 414; State v. Reidemire, 70 Mo. 173; 36 Am. Rep. 462.

§ 48. Test of capacity to contract.

Partial insanity upon a subject in no wise connected with a contract will not invalidate it: Boyce v. Smith, 9 Gratt. (Va.) 704; 60 Am. Dec. 303; and contracts made with lunatics are not all absolutely void: Richardson v. Strong, 13 Ired. L. (N. C.) 106; 55 Am. Dec. 430; as for goods furnished innocently on his order: See Beals v. Lee, 10 Pa. St. 96; 40 Am. Dec. 573. Nor will weakness of mind arising from old age or other causes invalidate an obligation executed

by the party. But if the instrument was procured by the use of undue influence or fraud, it would be invalid, and set aside in equity; and imbecility of mind and understanding usually constitutes a material ingredient in determining the question whether a contract has been obtained by fraud, imposition or undue influence: Juzan v. Toulman, 9 Ala. 662; 44 Am. Dec. 448; Smith v. Beatty, 2 Ired. Eq. (N. C.) 456; 40 Am. Dec. 435; Clark v. State, 12 Ohio, 483; 40 Am. Dec. 481.

The acts and contracts of persons of weak understanding, or imbecility of mind, and who are therefore liable to imposition, will be held void if the nature of the act or contract justifies the conclusion that the party has not exercised a deliberate judgment, but has been imposed upon, circumvented, or overcome by cunning, artifice, or undue influence. And a contract may be set aside in equity where there is imbecility or weakness of mind arising from old age, sickness, intemperance or other cause, and manifest inadequacy of consideration; or where there is weakness of mind and circumstances of undue influence and advantage See Equity Jurisprudence, vol.