C.R.S. § 16-7-208: Failure or refusal to plead.

If a defendant refuses to plead, or if the court refuses to accept a plea of guilty or a plea of nolo contendere (no contest), or if a corporation fails to appear, the court shall enter a plea of not guilty. If for any reason a plea has not been entered, the case shall for all purposes be considered as one in which a plea of not guilty has been entered.