Click to Call: (303) 725-0017

Express Consent Laws

Although you technically don’t have to hit the legal limit to be charged with DUI, most drinking and driving arrests stem from a failed chemical BAC test. Colorado uses these chemical tests to determine a person’s blood alcohol concentration with either a breath or blood sample. You do have the right to refuse any of these tests but doing so will be in violation of Colorado’s expressed consent laws.

Expressed consent is essentially the idea you’ve already implicitly given your consent to chemical DUI testing by law enforcement if you’re driving on Colorado’s public roads. You can refuse testing, but by doing so you’re violating expressed consent laws. As a result, you’ll be administratively penalized by the Colorado Department of Motor Vehicles (DMV). Instead of a criminal penalty, you’ll have your license suspended and the only way to contest it is with a hearing.

DUI Attorney Explains Expressed Consent Law in Denver, CO

If you were arrested for a DUI or DWAI charge involving a chemical test of your breath or blood sample, then contact an experienced defense attorney at the Law Office of Matthew A. Martin, P.C..

Matthew Martin represents clients charged with DUI related offenses throughout the state of Colorado, including the city of Denver. He also represents clients on drunk driving charges in the surrounding areas in the Front Range region including:

    • Arapahoe County in Centennial and Littleton
    • Boulder County in Boulder and Longmont
    • Adams County in Brighton
    • Broomfield County in Broomfield
    • Douglas County in Castle Rock
    • Jefferson County in Golden

Call (303) 725-0017 for a free and confidential consultation to discuss any administrative suspension of your driver’s license, the pending criminal charge, and the best ways to fight the charge.

Information Center:


Back to top

Law Enforcement Procedures During DUI Testing

Colorado’s DUI statute gives the suspect the right to choose between a breath test or a blood test as provided in section 42-4-1301.1(2)(a)(I), C.R.S.

If the driver specifically requests a blood test, then he must be given must be a blood test. If the driver specifically requests a breath test, then a breath test must be given.

In fact, the officer’s failure to give a blood test to a driver who requests one can result in dismissal of the case. People v. Null, 233 P.3d 670 (Colo. 2010). But after the DUI or DWAI arrest, if the officer has reasonable grounds to believe that drugs are involved, then the officer may choose to require a blood test. In those cases, the choice of test or tests does not in any way belong to the defendant as explained by Section 42-4-1301.1(2)(b)(I), C.R.S.

Colorado law does not provide any express statutory provision that allows the officer to request more than one type of chemical test. On the other hand, the statute does not expressly prohibit an officer from requesting more than one test. In other words, nothing in the statutory language ties together subsections 1301.1(2)(a)(I) and (2)(b)(I), except for the fact that the two provisions are in the same statute.

Subsection 1301.1(2)(a)(I) authorizes a breath or blood test if an officer has probable cause to believe a driver is under the influence of alcohol. Subsection 1301.1(2)(b)(I) authorizes a blood or breath sample if an officer has probable cause to believe a driver is under the influence of drugs and requiring the test is reasonable.


Back to top

DUI Blood Test Regulations in Colorado

Blood alcohol content is measured by the number of grams of alcohol contained in one hundred milliliters of blood, expressed as a percentage. In DUI cases, the prosecutor will simply refer to the resulting decimal, such as 0.08, as the blood alcohol content.

After a DUI arrest in Colorado, the arresting officer might give you the choice between submitting to a breath test or a blood test.

The officer might insist on a blood test if the driver is unconscious or if the arresting officer suspects that the driver was intoxicated, in whole or in part, by drugs.

If the driver refuses to provide a sample for a chemical test, the arresting officer may apply for a warrant to force a blood draw as provided by C.R.S. § 42-4- 1301.1(3) if the arresting officer has probable cause to believe that the driver committed any of the following offenses:

  • Vehicular homicide pursuant to section 18-3-106(1)(b), C.R.S.
  • Vehicular assault pursuant to section 18-3-205(1)(b), C.R.S.
  • Criminally negligent homicide pursuant to section 18-3-105, C.R.S. or
  • Third degree assault pursuant to section 18-3-204, C.R.S.,

For felony DUI cases, the officer is trained to get six tubes of blood. Ideally, the officer wants to take the third and fourth tubes an hour after the first two tubes. After another hour, the fifth and sixth tubes are drawn.

The arresting officer might attempt to obtain the blood sample pursuant to the Expressed Consent law if the driver is unconscious as provided by C.R.S. § 42-4-1301.1(8). Alternatively, the officer might seek a search warrant for the blood.

By taking blood samples over the course of three hours, the driver’s BAC at the time of driving can be estimated by extrapolation.

Colorado law has strict requirements for obtaining a blood sample. Additionally, hospitals and other medical facilities have their own procedures for drawing blood and maintaining custody of the blood sample.


Back to top

Testing Kits for Drawing Legal Blood in Colorado

The arresting officer usually provides the specimen kit for the collection of the legal blood sample. The blood specimen kit and the specimen collection, must meet all the requirements listed in the CDPHE Rules and Regulations.

Each blood alcohol collection kit should include the following:

  • a chain of custody form
  • two test tubes containing a 1% sodium fluoride preservative
  • evidence seals
  • a non-alcohol antiseptic towelette

After the blood sample was collected, it must be analyzed in accordance with the CDPHE Rules and Regulations.


Back to top

Defenses in Blood Test Cases in Colorado

The most common defenses in a blood test case include showing:

  • the blood sample was improperly collected;
  • the officer failed to properly observe the blood being drawn from the defendant;
  • the officer failed to properly note the time and date the blood was drawn;
  • the person who withdrew the blood was not qualified to do so as required by the Colorado Revised Statute;
  • the crime lab was not properly accredited to analyze the blood for alcohol content.

Back to top

What Happens When You Violate Express Consent Laws in Colorado?

During a traffic stop, you may know you’ve had a few drinks and if you submit to a chemical DUI test then you’ll automatically be charged with DUI. Because of this, you may choose to instead violate express consent laws by refusing chemical testing. While this is your legal right, refusing a chemical BAC test does come with its own set of consequences.

Listed below are the penalties for refusing a Colorado DUI chemical test.

  • An automatic one-year suspension of your license
  • Designation as a “persistent drunk driver” by the Colorado DMV
  • Mandatory alcohol and drug education courses
  • Your car will have an ignition interlock device installed for at least one year following the restoration of your driving privileges
  • You must carry SR-22 even if you are not convicted of DUI

Back to top

Additional Resources

Express Consent Laws in Colorado | CO DMV – Visit the official website of the Colorado Department of Revenue to learn more about express consent laws. Access the site to read up on the penalties if you refuse testing, the length of restraint, and if you’re eligible for a restrictive license after suspension.

Colorado’s Drunk Driving Statute | CRS– Visit the official website for the Colorado General Assembly to read up on the legislation in regard to DUI, DWAI, express consent, and any other alcohol and driving related provision. Access the site to learn about express laws, what happens if you refuse a BAC test, the elements of DUI and DWAI and other information.


Back to top

DUI Attorney for Chemical Testing in Denver, CO

It can be difficult to determine whether it’s a good idea to refuse or comply with DUI chemical testing in Colorado. That is why we highly recommend you call an attorney before you make any decision like the excellent legal team at Law Office of Matthew A. Martin, P.C.. Attorney Matthew Martin can explain the potential penalties of each decision and then provide valuable advice, so you make the best possible choice. He can also serve as your defense if you’re charged with a crime or are in need for representation during a DUI DMV hearing.

Call (303) 725-0017 to set up your first consultation with Law Office of Matthew A. Martin, P.C. free of charge. Law Office of Matthew A. Martin, P.C. accepts clients throughout the greater Denver area and surrounding areas including Boulder County, Broomfield County, Douglas County, Jefferson County, Broomfield County, Adams County, and Arapahoe County.


Back to top