42-4-1707. Summons and complaint or penalty assessment notice for misdemeanors, petty offenses, and misdemeanor traffic offenses - release - registration. (6)
If the defendant is otherwise eligible to be issued a summons and complaint or a penalty assessment notice for a violation of this title punishable as a misdemeanor, petty offense, or misdemeanor traffic offense and if the defendant does not possess a valid Colorado driver's license, the defendant, in order to secure release, as provided in this section, must either consent to be taken by the officer to the nearest mailbox and to mail the amount of the penalty and surcharge thereon to the department or must execute a promise to appear in court on the penalty assessment notice or on the summons and complaint. If the defendant does possess a valid Colorado driver's license, the defendant shall not be required to execute a promise to appear on the penalty assessment notice or on the summons and complaint. The peace officer shall not require any person who is eligible to be issued a summons and complaint or a penalty assessment notice for a violation of this title to produce or divulge such person's social security number.
Nonetheless, carrying an ID is required when you're driving or flying. Driving without a license is a crime, and no one is allowed to board an airplane without first presenting proper identification. These requirements have been upheld on the premise that individuals who prefer not to carry ID can choose not to drive or fly.
http://knowmyrights.org/faq/4th-amendment/when-do-i-have-to-show-id.html
42-2-101. Licenses for drivers required.
42-2-101(1) Driver's license-Driving W/OUT, Guilty. Class plea(T2)
When you are operating a motor vehicle you are obligated to provide drivers license when asked for it, along with proof of insurance and registration or its ticket able under operating a motor vehicle without a license no insurance and so forth. If your behind that wheel with keys in the ignition your operating that vehicle and need to be license to do so.