able to prove the defendant’s sanity unless it can show that the defendant’s mental state changed abruptly sometime after the offense was committed in Denver.
In proceeding under 1965 Perm. Supp., C.R.S. 1963, 39-8-3, the cause must be set for trial to the jury on the issue of insanity only, subject to two exceptions. The exceptions are that (1) the cause shall be set for trial to the court on the issue of insanity only, if agreed to in writing by the district attorney, the court, and the defendant; or (2) the cause shall be set for trial to the jury on the issue of guilt only, at the request of the defendant and upon the motion of the defendant.
If the cause is set for trial to the jury on the issue of insanity only, and the defendant is found sane, then the defendant shall be tried on the issue of guilt at a later time to a different jury. Likewise, if the cause is set for trial to the jury on the issue of guilt only, and the defendant is found guilty, then the defendant shall be tried on the issue of insanity at a later time to a different jury. For a discussion of the constitutional ramifications of bifurcated trials in cases involving an insanity defense, see Comment, Due Process and Bifurcated Trials: A Double-Edged Sword, 66 Nw.U. L. Rev. 327 (1971); Shadoan, Raising the Insanity Defense: The Practical Side, 10 Amer. Crim. L. Rev. 533 (1972). See also, Bendt, Balcanoff and Tragillis, Psychiatric Examination of Alleged Offenders, 58 A.B.A.J. 371 (April, 1972).
In all sanity trials which are conducted in accordance with 1965 Perm. Supp., C.R.S. 1963, 39-8-3, a presumption of sanity operates until some evidence to the contrary is presented. Elliott v. People, 176 Colo. 373, 490 P.2d 687 (1971); Palmer v. People, 162 Colo. 92, 424 P.2d 766 (1967); Henderson v. People, 156 Colo. 229, 397 P.2d 872 (1965);Mundy v. People, 105 Colo. 547, 100 P.2d 584 (1940). The requirement that the defendant present only some evidence of insanity to rebut the presumption is wholly proper, since a presumption is not evidence, and the primary purpose of the presumption of sanity is merely procedural convenience in those trials in which sanity is not really an