Underage Drinking and Driving, or UDD, is defined under the Colorado Revised Statutes Section 42-4-1301(2)(a.5).
In Colorado, it is a class A traffic infraction (link to potential penalties tab) for any person under twenty-one years of age to drive any vehicle in this state when the person's blood or breath alcohol content, as shown by analysis of the person's breath, is at least 0.02 but not more than 0.05 at the time of driving or within two hours after driving.
In addition to the standard penalties, a conviction for Underage Drinking and Driving in Colorado affects your driver's license. See an attorney for more information.