See also: COMPETENCE
;

§ 1.  Presumptions

Sanity.  All persons are presumed sane.{footnote}Sloger v. Sloger, 26 Ill. 2d 366, 186 N.E.2d 288 (1962).{/footnote} 

§ 2.  Expert Opinion

Under the federal rules, experts may not testify as to the ultimate issue of whether a defendant in a criminal case had the requisite mental state or condition for the crime charged.{footnote}FRE 704(b).  But check United States v. Mattson, 469 F.2d 1234 (9th Cir. 1972)(before FRE).{/footnote}  An expert may, however, go so far as to testify whether the mental defect suffered by the defendant would affect a person‘s ability to appreciate the nature and quality of his acts, since this goes to the general nature of the mental defect.{footnote}United States v. Kristiansen, 901 F.2d 1463 (8th Cir. 1990).{/footnote}

New Disorders.  Disorders and theories which have not been shown to have gained wide acceptance among other experts in the field will not be admissible to support a defendant’s insanity plea.{footnote}United States v. Torniero, 735 F.2d 725 (2d Cir. 1984).{/footnote}  See also SCIENTIFIC EVIDENCE.

Lay Testimony

In some courts, lay opinion testimony of persons who have observed the defendant is admissible on the issue of insanity{footnote}United States v. Hall, 583 F.2d 1288 (5th Cir. 1978)(lay opinion sufficient to meet prosecution’s burden of proof).{/footnote} or mental incapacity.{footnote}United States v. Caldwell, 543 F.2d 1333, 1349 n. 74 (C.A.D.C.Cir. 1974); Annot., 40 A.L.R.2d 15.  Check Wigmore Sec 1938 at 3646.{/footnote}

Subscribing witnesses.  Witnesses who attest to a writing may testify as to the signers’ mental capacity or incapacity at the time.{footnote}John Hancock Mutual Life Ins. Co. v. Dutton, 585 F.2d 1289 (5th Cir. 1978); Annot., 155 A.L.R. 281.{/footnote}  See also OPINIONS–Lay Opinion: Mental State.

Lack of Mens Rea

Psychiatric testimony is admissible to show the defendant’s mental condition where that mental condition would affect the defendant’s capacity to from the requisite mens rea.{footnote}United States v. Darby, 857 F.2d 623 (9th Cir. 1988).

Check Insanity Defense Reform Act; Check United States v. Pohlot, 827 F.2d 889 (3d Cir. 1987).{/footnote}

Court-ordered Examinations

Under the federal rules, statements made by the defendant during a court-ordered psychiatric examination are inadmissible on the issue of guilt.{footnote}Fed. R.Crim. P. 12.2(c).{/footnote}  See also PSYCHOTHERAPIST-PATIENT PRIVILEGE–Proceedings Where the Privilege Is Applicable.