Drugs, penalties and express consent

Key points

1. Impaired driving is proven by driving behavior and the totality of circumstances, not only by BAC.

   Source: Handbook p. 3

   “Impaired driving convictions are not proven only by the driver's Blood Alcohol Concentration (BAC), but by the impaired driving behavior and a totality of circumstance.”
   Colorado Driver Handbook, Handbook p. 3

2. Under 21, a first DUI or DWAI can bring revocation if you skip a court ordered program, and a second or third means mandatory revocation.

   Source: Handbook p. 4

   “Any driver younger than 21, convicted of DUI or DWAI, is subject to revocation of their driver license for the first conviction if they fail to complete a court-ordered evaluation or program. A second or third conviction is a mandatory revocation of their license.”
   Colorado Driver Handbook, Handbook p. 4

3. Using marijuana or other drugs for medical purposes is not a defense for DUI or DWAI.

   Source: Handbook p. 4

   “The fact that marijuana or other drugs were used for medicinal purposes is not a defense for DUI or DWAI.”
   Colorado Driver Handbook, Handbook p. 4

4. Blood containing 5 nanograms of THC per milliliter allows an inference of DUI.

   Source: Handbook p. 5

   “There is a permissible inference that a driver was DUI if the driver's blood contained 5 nanograms of THC per milliliter (ng/ml) of blood.”
   Colorado Driver Handbook, Handbook p. 5

5. By driving in Colorado, you agree to a chemical test for alcohol or drugs.

   Source: Handbook p. 5

   “when you operate a motor vehicle in the Centennial State, you agree to take a chemical test to determine the presence of alcohol and/or drugs in your blood.”
   Colorado Driver Handbook, Handbook p. 5

6. Refusing a test means a one year revocation and an ignition interlock for two years.

   Source: Handbook p. 5

   “If you refuse to take the test or do not comply with being tested, your driver license will be revoked for one year and you will be required to install an ignition interlock device on any motor vehicle you drive for two years.”
   Colorado Driver Handbook, Handbook p. 5

7. Colorado does not allow plea bargaining out of an alcohol or drug driving offense.

   Source: Handbook p. 5

   “Colorado law does not allow you to plea bargain out of an alcohol or drug related driving offense.”
   Colorado Driver Handbook, Handbook p. 5

Numbers to know

3 questions from the Colorado practice test

1. 1. What does Colorado's handbook say about marijuana used for medical purposes and DUI or DWAI?

   1. Medical use is not a defense to DUI or DWAI
   2. Medical use always makes driving legally safe
   3. Medical use is a defense whenever the driver has a prescription
   4. Medical use matters only for commercial drivers
   Show answer

   Medical use is not a defense to DUI or DWAI. The handbook states that marijuana or other drugs used for medical purposes do not provide a defense to DUI or DWAI. A prescription does not erase impairment or transform unsafe driving into legal driving. The choices “Medical use always makes driving legally safe” and “Medical use is a defense whenever the driver has a prescription” improperly create immunity, while the commercial-driver limitation is not in the rule. Medication decisions belong before the trip: check warnings, ask a health professional about side effects, and do not drive when a substance can impair safe operation.

2. 2. What THC level creates a permissible inference that a driver was DUI in Colorado?

   1. 15 nanograms per milliliter of saliva
   2. 0.08 nanograms per breath sample
   3. 5 nanograms per milliliter of blood
   4. Any detectable THC level in urine
   Show answer

   5 nanograms per milliliter of blood. Colorado separates the THC inference from alcohol BAC rules. The handbook says 5 nanograms of THC per milliliter of blood permits an inference of DUI, while DWAI has no THC permissible inference level. A saliva or urine figure is not the stated standard. The practical cue is that marijuana impairment can be judged through behavior as well as blood results.

3. 3. What consequences does Colorado list for refusing or failing to comply with a required chemical test?

   1. A lifetime revocation with no possibility of reinstatement
   2. A warning with no effect on driving privileges
   3. A 30-day license suspension and no vehicle device
   4. A one-year license revocation and a two-year ignition interlock requirement
   Show answer

   A one-year license revocation and a two-year ignition interlock requirement. If a driver refuses a required chemical test or does not comply with being tested, Colorado revokes the driver license for one year. The driver must also install an ignition interlock device on every motor vehicle driven for two years. A warning-only response omits both consequences, while a 30-day suspension understates the license action. Lifetime revocation is more severe than the handbook's stated result. The interlock requires a breath sample before starting and can request more samples while driving, so refusal affects both licensing and the conditions of later vehicle use.

Source: the Colorado Driver Handbook, Driving Under the Influence. This lesson is a plain English summary, not the law itself; where it differs, the manual and the statute govern. Last checked 2026-09-27.