What constitutes substantial evidence in a proceeding under section 1368 of the Criminal Code?

Appellant relies on Pate v. Robinson (1966) 383 U.S. 375, 86 S.Ct. 836, 15 L.Ed.2d 815, which stands for the proposition that an accused has a constitutional right to a hearing on present sanity if he comes forward with substantial evidence that he is incapable, because of mental illness, of understanding the nature of the proceedings against him or of assisting in his defense. Once such substantial evidence appears, a doubt as to the sanity of the accused exists and a hearing is mandatory no matter how persuasive other evidence, testimony of prosecution's witnesses, or the court's own observations of the accused may be to the contrary. (People v. Pennington (1967) 66 Cal.2d 508, 518, 58 Cal.Rptr. 374, 426 P.2d 942.)

[115 Cal.App.3d 503] What constitutes substantial evidence in a proceeding under section 1368 cannot be answered by a simple formula applicable to all situations. (People v. Laudermilk (1967) 67 Cal.2d 272, 283, 61 Cal.Rptr. 644, 431 P.2d 228, cert. den. 393 U.S. 861, 89 S.Ct. 139, 21 L.Ed.2d 128.) Where there is no substantial evidence to raise the required doubt in the mind of the trial judge the failure to proceed under section 1368 sua sponte is not error. More is required to raise a doubt than mere bizarre actions, or bizarre statements, or statements of defense counsel that defendant is incapable of cooperating in his defense, or psychiatric testimony that defendant is immature, dangerous, psychopathic, or homicidal or such diagnosis with little reference to defendant's ability to assist in his own defense. (Id., 67 Cal.2d at p. 285, 61 Cal.Rptr. 644, 431 P.2d 228.) It is not enough that an expert state that the defendant is mentally ill or insane to satisfy the substantial evidence test. (People v. Zatko (1978) 80 Cal.App.3d 534, 548, 145 Cal.Rptr. 643.) The expert must state with particularity that in his professional opinion the accused is, because of mental illness, incapable of understanding the purpose or nature of the criminal proceedings being taken against him or is incapable of assisting in his defense or cooperating with counsel. (People v. Pennington (1967) 66 Cal.2d 508, 519, 58 Cal.Rptr. 374, 426 P.2d 942.) However, a single doctor's report which concludes that the defendant is incapable of standing trial, even in the face of other reports to the contrary, is substantial evidence requiring that a section 1368 proceeding be instituted. (People v. Zatko supra, 80 Cal.App.3d 534, 547, 145 Cal.Rptr. 643.)