(1) (a) The defense of insanity may only be raised by a specific plea entered at the time of arraignment; except that the court, for good cause shown, may permit the plea to be entered at any time prior to trial. The form of the plea is: Not guilty by reason of insanity; and it must be pleaded orally either by the defendant or by the defendant's counsel. A defendant who does not raise the defense as provided in this section is not permitted to rely upon insanity as a defense to the crime charged but, when charged with a crime requiring a specific intent as an element thereof, may introduce evidence of the defendant's mental condition as bearing upon the defendant's capacity to form the required specific intent. The plea of not guilty by reason of insanity includes the plea of not guilty.
(b) This subsection (1) applies to offenses committed before July 1, 1995.
(1.5) (a) The defense of insanity may only be raised by a specific plea entered at the time of arraignment; except that the court, for good cause shown, may permit the plea to be entered at any time prior to trial. The form of the plea is: Not guilty by reason of insanity; and it must be pleaded orally either by the defendant or by the defendant's counsel. The plea of not guilty by reason of insanity includes the plea of not guilty.
(b) This subsection (1.5) applies to offenses committed on or after July 1, 1995.
(2) If counsel for the defendant believes that a plea of not guilty by reason of insanity should be entered on behalf of the defendant but the defendant refuses to permit the entry of the plea, counsel may inform the court. The court shall then conduct an investigation as it deems proper, which may include the appointment of psychiatrists or forensic psychologists to assist in examining the defendant and advising the court. After its investigation, the court shall conduct a hearing to determine whether the plea should be entered. If the court finds that the entry of a plea of not guilty by reason of insanity is necessary for a just determination of the charge against the defendant, the court shall enter the plea on behalf of the defendant, and the plea entered has the same effect as though it had been voluntarily entered by the defendant.
(3) If a grand jury indictment or preliminary hearing has not been held prior to the entry of the plea of not guilty by reason of insanity, the court shall hold a preliminary hearing prior to the trial of the insanity issue. If probable cause is not established, the case must be dismissed, but the court may order the district attorney to institute civil proceedings pursuant to article 65 of title 27 if it appears that the protection of the public or the accused requires a civil proceeding.
(4) Before accepting a plea of not guilty by reason of insanity, the court shall advise the defendant of the effect and consequences of the plea.
Source: L. 72: R&RE, p. 226, � 1. C.R.S. 1963: � 39-8-103. L. 75: (3) amended, p. 926, � 26, effective July 1. L. 95: (1) amended and (1.5) added, p. 73, � 4, effective July 1. L. 2010: (3) amended, (SB 10-175), ch. 188, p. 783, � 21, effective April 29. L. 2013: (2) amended, (SB 13-116), ch. 115, p. 393, � 2, effective August 7. L. 2025: Entire section amended, (HB 25-1058), ch. 15, p. 40, � 4, effective August 6.
16-8-103.5. Impaired mental condition - when raised - procedure - legislative intent. (1) If the defendant intends to assert the affirmative defense of impaired mental condition, the defendant shall indicate that intention to the court and to the prosecution at the time of arraignment; except that the court, for good cause shown, shall permit the defendant to inform the court and the prosecution of the defendant's intention to assert the affirmative defense of impaired mental condition at any time prior to trial.
(2) If counsel for the defendant believes that an assertion of the affirmative defense of impaired mental condition should be entered on behalf of the defendant but the defendant refuses to permit counsel to offer such evidence, counsel may inform the court. The court shall then conduct an investigation as it deems proper, which may include the appointment of psychiatrists or forensic psychologists to assist in examining the defendant and advising the court. After its investigation, the court shall conduct a hearing to determine whether evidence of impaired mental condition should be offered at trial. If the court finds that the defense of impaired mental condition is necessary for a just determination of the charge against the defendant, the court shall inform the prosecution that the defense must be asserted at trial by the defendant and shall order the defendant's counsel to present evidence at trial on the defense of impaired mental condition.
(3) At the time when the defendant announces the defendant's intention to assert the affirmative defense of impaired mental condition, the court shall advise the defendant of the effect and consequences of asserting the defense.
(4) When the defendant indicates the defendant's intention to assert the defense of impaired mental condition, the court shall order an examination of the defendant pursuant to section 16-8-106. The court shall order both the prosecutor and the defendant to exchange the names, addresses, reports, and statements of persons, other than medical experts subject to the provisions of section 16-8-103.6, whom the parties intend to call as witnesses with regard to the affirmative defense of impaired mental condition.
(5) If the trier of fact finds the defendant not guilty by reason of impaired mental condition pursuant to section 18-1-803 (3), the court shall commit the defendant to the custody of the department of human services until such time as the defendant is found eligible for release pursuant to the standards set forth in sections 16-8-115 and 16-8-120. The executive director of the department of human services shall designate the state facility where the defendant is held for care and psychiatric treatment and may transfer the defendant from one institution to another if, in the opinion of the executive director, transferring the defendant is desirable to do so in the interest of the defendant's proper care, custody, and treatment or the protection of the public or the personnel of the facilities in question.
(6) It is the intent of the general assembly that the assertion of the affirmative defense of impaired mental condition not be made in a manner that it is used to circumvent the requirements of disclosure specified in rule 16 of the Colorado rules of criminal procedure.
(7) A defendant may raise impaired mental condition only through an assertion of affirmative defense.
(8) This section applies to offenses committed before July 1, 1995.
Source: L. 83: Entire section added, p. 673, � 3, effective July 1. L. 85: (6) and (7) added, p. 625, � 1, effective June 6. L. 87: (4) amended, p. 622, � 2, effective July 1. L. 94: (5) amended, p. 2648, � 117, effective July 1. L. 95: (8) added, p. 73, � 5, effective July 1. L. 2013: (2) amended, (SB 13-116), ch. 115, p. 394, � 3, effective August 7. L. 2025: Entire section amended, (HB 25-1058), ch. 15, p. 41, � 5, effective August 6.
Cross references: (1) For affirmative defenses generally, see � 18-1-407.
(2) For the legislative declaration contained in the 1994 act amending subsection (5), see section 1 of chapter 345, Session Laws of Colorado 1994.