Like several other states, Colorado has a law that requires drivers to submit to chemical testing for alcohol if a police officer requests one on the basis of probable cause to believe the driver is driving under the influence of alcohol (DUI) or driving while ability impaired (DWAI) in Colorado. Colorado refers to this rule as the “express consent” law.
Blood alcohol concentration (BAC) is usually determined by testing either a blood or a breath sample taken from the driver. A BAC of 0.08 percent or higher is considered a “per se” violation of Colorado’s DUI prohibition, while a BAC between 0.05 and 0.08 percent is considered evidence that the driver was DWAI. Both BAC readings, however, can be challenged in court.