If a police officer stops you in Colorado on suspicion of driving under the influence of alcohol or drugs, the officer can require you to take a chemical test of your blood or breath. The authority to require the test comes from Colorado’s express consent law, C.R.S. 42-4-1301.1, which also sets out who chooses the type of test, how long you have to take it, and what counts as a refusal. A refusal or a result of 0.08 or higher starts a license revocation at the Colorado Division of Motor Vehicles that proceeds on its own track, separate from the criminal DUI or DWAI case.

Express Consent

Express consent means that you have affirmatively given consent or permission to an action, either verbally or in writing. C.R.S. 42-4-1301.1 treats every person who drives a motor vehicle on a Colorado road as having already given consent to a blood or breath test for alcohol, and to a blood, saliva, or urine test for drugs, whenever an officer has probable cause to believe the driver was driving under the influence (DUI) or driving while ability impaired (DWAI).

Consent attaches to the act of driving a motor vehicle on a Colorado road, so the law covers:

• Drivers with a Colorado license
• Drivers licensed in another state who are passing through Colorado
• Drivers who have no license
• Drivers whose license is suspended or revoked

Roadside Tests

Express consent does not apply to roadside sobriety tests. The walk-and-turn, the one-leg stand, and the eye test where the officer passes a pen across your field of vision are observation tools an officer uses to build probable cause for an arrest. You can decline them, and declining is not a refusal under the express consent law and does not lead to a license revocation.

Preliminary Breath Tests

A preliminary breath test is the handheld device an officer may offer at the roadside, and it is different from the evidential breath test given after an arrest. C.R.S. 42-4-1301(6)(i) requires the officer to tell you that you may either refuse or agree to provide a breath sample for the preliminary test, and declining it is not a refusal under the express consent law. A preliminary test result is admissible only in a hearing on probable cause, outside the presence of a jury, and cannot be used at trial to prove your blood alcohol content.

For a driver under 21, the officer can ask for a preliminary breath test on reasonable suspicion that the driver consumed any amount of alcohol. If the officer arrests you and takes you to the station, the breath test given there is the one the express consent law applies to.

Chemical Tests

Once you are under arrest for DUI or DWAI, C.R.S. 42-4-1301.1 governs the chemical test itself and answers four questions: who picks the test, how much time you have, what happens when the chosen test cannot be completed, and who is allowed to take a blood sample.

Choosing Between a Blood Test and a Breath Test

If you are 21 or older and the officer suspects alcohol, you choose between a blood test and a breath test. Nothing in the statute requires the officer to read you a list of consequences before you choose; the officer only has to tell you to pick one. If you do not ask for a blood test, the officer obtains a breath sample.

Your choice is final. C.R.S. 42-4-1301.1(2)(a)(II) says that a driver who elects a test and then fails to take it, complete it, or cooperate in completing it is treated as having refused, so a driver who asks for blood and then changes to breath at the station has refused.

Two groups of drivers do not get the same choice:

• A driver under 21 may request a blood test, except in an underage drinking and driving (UDD) case, where the statute calls for a breath sample.
• In a drug case, the officer may require a blood, saliva, or urine test, and the officer chooses which one.

The Two-Hour Window

C.R.S. 42-4-1301.1(2)(a)(III) requires you to cooperate with the taking of the sample within two hours of when you were driving, and the two hours apply to both blood and breath. Two hours are measured from the time of driving, which is earlier than the time of arrest. A driver who stalls past the two hours has failed to cooperate, and the statute treats the delay as a refusal.

When Moorhead Law Group reviews an arrest report, the time of the stop and the time of the draw are the first two entries we compare, because a sample taken outside the two-hour window is open to challenge in both the criminal case and the DMV hearing.

Switching Tests in Extraordinary Circumstances

C.R.S. 42-4-1301.1(2)(a.5) lets the officer direct you to the other test when circumstances beyond the officer’s control prevent the test you chose from being completed within two hours. The statute names weather delays, power outages, malfunctioning breath test equipment, and high call volume that ties up medical personnel as circumstances that qualify, and it names inconvenience, a busy workload for the officer, and a minor delay that leaves time within the two hours as circumstances that do not. If the officer properly directs you to the other test and you decline it, the statute treats the decline as a refusal.

Who Can Draw Blood and Testing of Unconscious Drivers

C.R.S. 42-4-1301.1(6)(a) limits who may draw blood for a DUI test to a physician, a registered nurse, an emergency medical service provider whose scope of practice allows blood draws, or a technician whose normal duties include drawing blood under the supervision of a physician or registered nurse. A sample drawn by anyone else can be challenged.

Subsection (8) covers a driver who is unconscious, dead, or otherwise unable to consent because of a crash. Medical personnel may test that driver without consent, the statute makes the result admissible, and physician-patient privilege does not keep the result out. The Colorado Supreme Court upheld a warrantless blood draw from an unconscious driver under the statute in People v. Hyde (2017), and in Tarr v. People (2024) it limited Hyde to unconscious drivers, so a blood draw from an unconscious driver can still be challenged in the criminal case on Fourth Amendment grounds where the facts support it.

Refusing a Chemical Test

A refusal is a decision with consequences on two tracks. The DMV revokes your license through an administrative process, and the prosecutor can use the refusal against you in the criminal case. A refusal does not always end the testing, because the officer can apply for a search warrant for your blood. Tarr v. People (2024) holds that a conscious driver may revoke the consent the statute presumes, and that once consent is revoked the police generally need a warrant before drawing blood.

Conduct That Counts as a Refusal

Colorado law treats the following conduct as a refusal, the same as saying no:

• Starting the test and not completing it
• Declining to sign a release or consent form the officer or medical staff presents
• Delaying past the two-hour window
• Declining the test you chose after choosing it
• Telling the officer you will not take the test until you speak with a lawyer

License Revocation for a Refusal

If you refuse, C.R.S. 42-2-126 directs the DMV to revoke your license for one year on a first violation, two years on a second, and three years on a third or later violation. A refusal also places you in Colorado’s persistent drunk driver category, which is what brings the added requirements the DMV imposes after a refusal:

• An ignition interlock device for two years after your license is reinstated
• Enrollment in a Level II alcohol and drug education and treatment program
• An SR-22 certificate from your insurance company, which is proof of coverage the DMV requires before it issues an interlock-restricted license

A driver who was 21 or older at the time of the offense and refused can reinstate with an interlock after two months of the revocation have passed, and until then there is no probationary or work-restricted license for a refusal.

A Refusal Is Evidence at Trial

C.R.S. 42-4-1301(6)(d) makes a refusal admissible at trial and bars you from invoking the privilege against self-incrimination to keep it out. A prosecutor can tell the jury you refused and can argue that you refused because you expected to fail. A refusal case has no BAC number, so the prosecution builds the case on the officer’s observations, the roadside tests, and the refusal itself.

Test Results of 0.08 or Higher

A breath or blood result of 0.08 or higher brings a shorter revocation than a refusal. C.R.S. 42-2-126 sets nine months on a first violation, one year on a second, and two years on a third or later violation. C.R.S. 42-2-132.5(4)(a) lets a driver 21 or older who took the test apply for reinstatement with an interlock at any time, and a result of 0.15 or higher places the driver in the persistent drunk driver category with the two-year interlock and Level II treatment requirements that follow.

A revocation for a 0.08 result is an administrative action, and it takes effect whether or not the criminal case ends in a conviction. The potential penalties in the criminal case are covered on our Colorado DUI penalties page.

	Refusal	Result of 0.08 or higher
First violation	1 year	9 months
Second violation	2 years	1 year
Third or later violation	3 years	2 years
Wait before interlock reinstatement (age 21 and older)	2 months	None
Interlock period after reinstatement	2 years	Rest of the revocation period on a first result under 0.15; 2 years if 0.15 or higher or a second violation
Persistent drunk driver designation	Yes	Yes if 0.15 or higher, or on a second violation
Usable by the prosecutor at trial	The refusal	The BAC number

Drivers Under 21 and Commercial Drivers

Two groups face their own revocation schedules.

Drivers Under 21

A driver under 21 with a result of 0.02 to 0.079 faces what C.R.S. 42-2-126 calls an excess BAC underage revocation of three months on a first violation, six months on a second, and one year on a third or later violation. The revocation is separate from any criminal charge: a result of 0.02 to 0.05 supports a UDD charge under C.R.S. 42-4-1301(2)(a.5), and a result above 0.05 supports a DWAI charge. The DMV allows a probationary license after one month on a first violation if the result was under 0.05. A result of 0.08 or higher, or a refusal, puts an underage driver on the same revocation schedule as an adult, but C.R.S. 42-2-132.5(4)(a) bars a driver who was under 21 at the time of the offense from applying for interlock reinstatement until the license has been revoked for one year.

Commercial Driver’s License Holders

C.R.S. 42-4-1301.1(4) requires the officer to warn a commercial driver before the test that a refusal brings a 24-hour out-of-service order and a one-year loss of the privilege to drive a commercial vehicle. Colorado applies the one-year loss to a failed test as well as a refusal, and it applies whether or not you were driving a commercial vehicle at the time, as long as you held a commercial license or permit. A second violation is a lifetime disqualification, and a driver who was in a commercial vehicle with a result of 0.04 to 0.079 faces the same one-year and lifetime schedule for commercial privileges. No probationary license and no interlock reinstatement is available for commercial privileges. The regular license is a separate question: it is revoked on the adult schedule only when the result was 0.08 or higher or the driver refused, so a commercial driver with a result of 0.04 to 0.079 keeps the ability to hold a regular license for personal driving.

Requesting a Hearing

If you refused a chemical test, or you took a test and the result was 0.08 or higher, you may request a hearing within seven days of receiving the Express Consent Affidavit and Notice of Revocation from the officer or the notice letter from the DMV. A hearing is your only opportunity to contest the revocation before it takes effect.

The Seven-Day Deadline and the Temporary Permit

How the seven days start depends on the type of test:

• After a refusal or a breath test result of 0.08 or higher, the officer takes your license and gives you the affidavit and notice at the time of arrest. If your license was valid, the notice serves as a temporary permit good for seven days.
• After a blood test, the officer does not serve the notice at the roadside because the result is not back yet. Instead, the DMV mails the notice after the lab reports a result of 0.08 or higher, and C.R.S. 42-2-126 deems the notice received three days after mailing.

Once you request a hearing, the DMV can extend your driving privilege with additional temporary permits until the hearing officer issues a decision.

Issues the Hearing Officer Reviews

C.R.S. 42-2-126(8)(h) limits the hearing to a short list of questions:

• Whether you drove with a blood or breath alcohol content of 0.08 or higher at the time of driving or within two hours after driving (0.02 or higher if you are under 21)
• Whether you refused, if the revocation is based on a refusal
• Whether the officer’s initial contact with you and the arrest were valid, which you may challenge at the hearing, and if the evidence does not establish that both were valid the revocation does not stand

An arresting officer does not attend unless the hearing officer requires it or you serve a subpoena on the officer at least five calendar days before the hearing. When the officer is absent, the hearing officer rules on the officer’s written report. Moorhead Law Group subpoenas the officer in refusal cases because whether a refusal happened depends on what the officer said and did at the station, and a written report answers fewer of those questions than cross-examination does.

License Reinstatement Before the Revocation Ends

C.R.S. 42-2-132.5(4)(a) lets a driver who was 21 or older at the time of the offense reinstate with an ignition interlock device before the full revocation period has passed: at any time after a revocation for a 0.08 result, and after two months of the revocation for a refusal. Reinstatement requires a signed lease for an interlock in every vehicle you own or drive, proof of financial responsibility (an SR-22) kept on file with the DMV for at least three years, and, for a refusal or a result of 0.15 or higher, enrollment in Level II treatment. How long the interlock stays on depends on the reason for the revocation:

• After a first 0.08 result under 0.15, the interlock stays for the time left on the nine-month revocation, and the DMV can remove it sooner after four consecutive monthly reports with no failed breath samples and no tampering.
• After a refusal or a result of 0.15 or higher, the interlock stays for at least two years after reinstatement.
• After a second or later alcohol-related revocation of any kind, the persistent drunk driver rule applies and the interlock stays for at least two years.

Frequently Asked Questions

Can I talk to a lawyer before choosing a test?

No. In Calvert v. State Department of Revenue (1974), the Colorado Supreme Court said the right does not exist and that insisting on a lawyer before choosing is generally treated as a refusal. The same decision set aside the driver’s revocation because the officers had read him his Miranda rights, which mention a right to counsel, and never told him those rights did not apply to the test choice. If an officer read you Miranda rights and then demanded a test without clarifying the difference, the refusal can be contested at the DMV hearing on that basis.

Does the officer have to read me an advisement?

No formal advisement of the consequences of refusing is required by the statute. An officer only has to tell you to choose between a blood test and a breath test, and in a drug case the officer names the test. A commercial driver is the exception, because C.R.S. 42-4-1301.1(4) requires the officer to warn a commercial driver about the out-of-service order and the one-year loss of commercial privileges.

Does express consent apply if I have an out-of-state license?

Yes. Consent comes from driving a motor vehicle on a Colorado road. If you refuse or fail a test with an out-of-state license, the DMV revokes your privilege to drive in Colorado, and your home state may take its own action against your license under the Driver License Compact, C.R.S. 24-60-1101.

Does refusing the roadside breath test count as a refusal?

No. A preliminary breath test at the roadside is voluntary, and declining it has no effect on your license. Refusal rules apply to the evidential blood or breath test requested after the arrest.

What happens if I chose a blood test and no one was available to draw it?

An officer can direct you to a breath test instead when circumstances outside the officer’s control keep the blood draw from happening within two hours. If you then decline the breath test, the statute treats the decline as a refusal. If the officer switches you to breath for convenience with no circumstance outside the officer’s control, the switch can be challenged at the hearing.

Can I be tested if I was unconscious after a crash?

Yes. C.R.S. 42-4-1301.1(8) lets medical personnel draw and test blood from a driver who is unconscious, dead, or otherwise unable to consent, and the statute makes the result admissible without your agreement. Physician-patient privilege does not keep the result out of the case, and any challenge to the draw is made in the criminal case on Fourth Amendment grounds.

Contact an Experienced DUI/DWAI Attorney

You have the right to be represented by an attorney at the DMV hearing and in the criminal case. Moorhead Law Group represents Boulder County drivers in both, requests the hearing within the seven-day window, subpoenas the arresting officer, and challenges the stop, the probable cause finding, the two-hour window, how the officer presented your test choice, and who drew the blood. Where the test was taken outside the statute’s requirements, we ask the judge to keep the result out of the criminal case.

If you have been arrested and charged with a DUI or DWAI, contact Colorado dui attorneys of The Moorhead Law Group at 303-447-1400 or online today to discuss your options and rights.

References and Additional Reading

• R.S. 42-4-1301.1, Expressed consent for the taking of blood, breath, urine, or saliva sample: https://colorado.public.law/statutes/crs_42-4-1301.1
• R.S. 42-4-1301, Driving under the influence (subsections (6)(d) and (6)(i)): https://colorado.public.law/statutes/crs_42-4-1301
• R.S. 42-2-126, Revocation of license based on administrative determination: https://colorado.public.law/statutes/crs_42-2-126
• R.S. 42-2-132, Period of suspension or revocation (Level II and interlock requirements for persistent drunk drivers): https://colorado.public.law/statutes/crs_42-2-132
• R.S. 42-2-132.5, Mandatory and voluntary restricted licenses following alcohol convictions (interlock reinstatement): https://colorado.public.law/statutes/crs_42-2-132.5
• R.S. 42-1-102(68.5), Definition of persistent drunk driver: https://colorado.public.law/statutes/crs_42-1-102
• Calvert v. State, Department of Revenue, 519 P.2d 341 (Colo. 1974), no right to counsel before choosing a test, and refusal set aside where Miranda warnings caused confusion: https://law.justia.com/cases/colorado/supreme-court/1974/26021.html
• People v. Hyde, 2017 CO 24, warrantless blood draw from an unconscious driver upheld under the statute: https://law.justia.com/cases/colorado/supreme-court/2017/15sa291.html
• Tarr v. People (Colo. 2024), a conscious driver may revoke statutory consent, after which police generally need a warrant: https://law.justia.com/cases/colorado/supreme-court/2024/22sc226.html
• Colorado Department of Revenue, Express Consent: https://cdor.colorado.gov/express-consent
• Colorado Department of Transportation, Colorado’s Expressed Consent Law: https://www.codot.gov/safety/impaired-driving/expressed-consent