C.R.S. § 16-7-205
16-7-205. Pleas authorized on arraignment
16-7-205. Pleas authorized on arraignment. (1) A defendant personally, or, where permissible, by counsel may orally enter:
(a) A plea of guilty; or
(b) A plea of not guilty; or
(c) A plea of nolo contendere (no contest) with the consent of the court; or
(d) A plea of not guilty by reason of insanity, in which event a not guilty plea may also be entered.