Colorado DUI Laws


Colorado DUI Laws

Colorado has four basic categories of drunk / drugged driving laws:

  • Colorado DUI
  • Colorado DUI “per se”
  • Colorado DWAI, and
  • Colorado UDD (underage drinking and driving).

The definition of each of these charges is set forth in Colorado Revised Statutes, 42-4-1301, C.R.S. To help you better understand the differences, our knowledgeable Colorado DUI defense lawyers discuss the following, below.

1. What is a Colorado DUI?

You drive under the influence of alcohol and/or drugs in Colorado when:

  1. you drive under the influence of alcohol and/or one or more drugs, and
  2. as a result, you are substantially incapable, mentally and/or physically, to safely operate a vehicle.1

In other words, this is what we typically think of as drunk driving or driving under the influence of drugs (DUID). DUI is usually a misdemeanor in Colorado. Please see our article on Colorado DUI penalties for more details.

2. What is a Colorado DUI per se?

You also commit DUI in Colorado when you drive with a blood alcohol concentration (“BAC”) of .08% or higher—regardless of your actual level of impairment. This is known as Colorado's “per se” DUI law.2

“Per se” is a Latin phrase meaning “in itself.” In essence, the Colorado legislature has decided that as a matter of law, you will be considered too drunk to drive if your BAC is .08% or higher, even without any further proof of intoxication.

However, as the best Colorado DUI lawyers know, evidence that you were driving safely and showed no other signs of intoxication can be used to show that your chemical test results may have been wrong. If you have been arrested for drunk driving in Colorado, we invite you to call us for a free consultation to learn more about how this is done.

3. What is a Colorado DWAI?

DWAI stands for “driving while ability impaired.” You commit a Colorado DWAI when you drive and you are affected by alcohol and/or drugs in “the slightest degree.”3

"The slightest degree” means you are less able mentally and/or physically to operate a vehicle safely than you ordinarily would have been. So as you can see, the degree of impairment required for a DWAI is not very substantial. And while DWAI is not as serious an offense as DUI, it is still usually a misdemeanor crime.

Generally, you will be charged with DWAI when your BAC is .05% or higher, but less than .08%. This is sometimes erroneously referred to as a Colorado DWAI per se.

However, there is no law in Colorado making it illegal as a matter of law to drive with a BAC of .05% unless you are under 21 years of age. Rather, it is a permissible inference that if you drove with a BAC of at least .05% (but under .08%) the alcohol affected your driving. But unlike a DUI per se, this inference can be directly countered with evidence that your driving was, in fact, fine.

4. What is a Colorado UDD?

UDD stands for “underage drinking and driving.” Colorado's UDD law is sometimes referred to as its “zero tolerance” law for drivers under the age of 21. To some extent, it is much like Colorado's per se DUI law, in that it applies without regard to your actual driving.

If you are under 21 and you drive in Colorado, you are subject to Colorado's DUI and DWAI laws. But even if your driving is not negatively impacted, if you are under 21 and your BAC is .02% for any reason, you have violated Colorado's UDD law.4

5. How is BAC measured?

BAC is measured as grams of alcohol per 100 milliliters of blood. This amount can be measured directly if you take a DUI blood test. If you take a DUI breath test, however, your BAC cannot be measured directly. Instead, the breath analyzer--usually an Intoxilyzer 9000-- will measure the amount of alcohol that has passed from your blood into your lungs. It will convert this measurement into the equivalent BAC based on an average conversion rate (known as a partition ratio). Whichever test you choose, however, the more alcohol in your system, the higher your BAC.

Also see our general article on Colorado DUI chemical tests: Breath, blood, refuse?

6. How do I fight a drunk driving charge?

Drunk driving defenses fall into three basic categories:

  • Unlawful arrest,
  • DUI testing errors, and
  • No proof that you drove drunk (for DWAI charges).

However, there are numerous ways to fight Colorado drunk driving accusations. One of our friendly Colorado DUI defense attorneys would be more than happy to talk to you and explore the best Colorado DUI defenses for your case. 

Call us for help…

If you or someone you know has been charged with violation of Colorado's laws on drinking and driving laws, we invite you to contact us for a free consultation.

Our passionate and compassionate Colorado DUI defense attorneys represent clients throughout the state. Communities we serve include Denver, Colorado Springs, Aurora, Fort Collins, Lakewood, Thornton, Arvada, Westminster and Centennial.

For a quick response contact one of our skilled DUI defense lawyers using the form on this page or at:

Colorado Legal Defense Group
4047 Tejon Street
Denver, CO 80211
(303) 222-0330

Legal references:

  1. 42-4-1301 (1) (a) and (f), C.R.S.
  2. 42-4-1301 (2), C.R.S.
  3. 42-4-1301 (1) (b), C.R.S.
  4. 42-4-1301 (2) (d), C.R.S.


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