Have A Question? Search This Site:
In Colorado, DUI laws are not always as straightforward as people think. Many drivers assume that failing a breath test — commonly known as a breathalyzer — is the only way they can be arrested for DUI. But the reality is more complex. The state’s DUI enforcement system is built on more than just numbers. In fact, Colorado law allows for DUI arrests even when a breath test result is below the legal limit, or if no breath test is taken at all.
The short answer: Yes, you can be arrested for DUI in Colorado without failing a breath test. Law enforcement uses a combination of observations, physical signs, and behavioral evidence to assess impairment. If an officer believes you are too impaired to drive safely — even without a high BAC — an arrest may still occur.
This post will clarify how DUI arrests happen in Colorado, how much weight breath tests carry in the process, and what other forms of evidence can lead to an arrest. It’s important to understand the full picture so that drivers in Colorado can stay informed and cautious on the road — whether or not a breath test is part of the encounter.
How Colorado Defines DUI and Impairment
Colorado law defines DUI (Driving Under the Influence) as operating a vehicle while your ability to drive is substantially impaired by alcohol, drugs, or a combination of both. The standard 0.08% BAC limit is just one method of proving this impairment — it’s not the only one.
Impairment can also be established through:
- Field sobriety test performance
- Driving behavior before the stop
- Physical signs like slurred speech or bloodshot eyes
- Odor of alcohol or marijuana
- Poor coordination or confusion
Even with a BAC below 0.08%, you could be charged with DWAI (Driving While Ability Impaired) if there are signs that alcohol or drugs have affected your ability to drive safely. The legal threshold for DWAI in Colorado begins at a BAC of 0.05%, but the charge can also be supported by observed impairment alone.
In other words, the law doesn’t require a failed breath test to justify an arrest. It only requires that the officer has probable cause to believe you are impaired.
The Role of Field Sobriety Tests in DUI Arrests
Field sobriety tests (FSTs) are often the first step officers use to assess impairment. These tests involve a series of physical and mental tasks that help gauge coordination, balance, and the ability to follow instructions. They play a critical role in DUI arrests, particularly when a breath test is not failed or not administered.
Common FSTs used in Colorado include:
- Horizontal Gaze Nystagmus (HGN): Tracks eye movement while the subject follows a moving object
- Walk-and-Turn: Requires walking heel-to-toe in a straight line, turning, and walking back
- One-Leg Stand: Tests balance and focus while standing on one foot for a timed period
Poor performance on these tests can be enough for an officer to believe the driver is impaired — regardless of breath test results. In some cases, drivers who pass a breath test still fail multiple field sobriety tests, leading to a DUI arrest.
FST results are subjective, but they’re used alongside other observations to form a complete picture of a driver’s condition.
Can Refusing a Breath Test Still Lead to Arrest?
Yes. Colorado operates under express consent laws, which means drivers agree to take a chemical test if lawfully requested by an officer. Refusing a breath or blood test does not prevent arrest — in fact, it often strengthens the officer’s suspicion of impairment.
Refusal may result in:
- Immediate license suspension (typically for one year on the first offense)
- Mandatory ignition interlock device if driving privileges are restored
- Use of the refusal as evidence in a DUI case
In some cases, officers may still obtain a blood test after a refusal, especially if a warrant is granted. Refusing the test does not stop the legal process, and it can lead to separate administrative penalties through the Colorado DMV.
In short, not taking a breath test doesn’t eliminate the risk of arrest — and may carry its own set of serious consequences.
Arrests Based on Observed Behavior Alone
Even if a breath test shows a BAC under the legal limit — or no test is conducted — an officer can arrest a driver based on their overall behavior and appearance. This includes how the driver was operating the vehicle and how they responded to questions or instructions.
Examples of behavior that can justify a DUI arrest include:
- Swerving or driving erratically
- Slurred or slow speech
- Difficulty maintaining balance
- Fumbling with documents
- Confusion or contradictory answers
These signs, combined with field sobriety results and other physical indicators, can support an arrest even if the BAC is below 0.08%.
This is especially relevant in cases involving drug-related impairment, where a breath test for alcohol may not detect the presence of substances like marijuana, prescription medication, or other drugs. In these cases, a blood test or officer training in drug recognition may be used to support the arrest.
Drug-Related DUIs Without a Breath Test
Breath tests measure alcohol — but they do not detect drugs. For drivers under the influence of cannabis, prescription drugs, or other controlled substances, impairment must be assessed through non-breath-based methods.
Officers trained as Drug Recognition Experts (DREs) may conduct evaluations that include:
- Eye examinations
- Pulse and body temperature checks
- Observation of muscle tone and coordination
- Interview and behavior assessment
If the officer suspects drug impairment, they may request a blood test, which is capable of detecting a wide range of substances. Colorado law allows for DUI arrests based on drug impairment, even if no alcohol is detected at all.
This is especially important in Colorado, where recreational marijuana is legal. Legal status doesn’t change DUI laws — drivers can still be arrested if they are judged to be impaired while driving, regardless of the substance involved.
The Importance of Officer Discretion and Probable Cause
In every DUI case, the arrest decision rests on a combination of evidence and officer judgment. Colorado officers are trained to use their discretion in deciding whether a driver appears too impaired to safely operate a vehicle.
An officer’s ability to make an arrest does not require a failed breath test — only probable cause based on the totality of the situation. That includes:
- Observed behavior while driving
- Physical and verbal signs of intoxication
- Results from field sobriety tests
- Refusal to comply with testing or instructions
Once arrested, the legal process continues with chemical testing, DMV hearings, and possibly court proceedings. But the initial arrest can occur before any test is failed — and sometimes even without one being taken at all.
Understanding this discretion helps clarify why relying on breath test results alone doesn’t provide full protection against DUI arrest in Colorado.
FAQ: DUI Arrests Without a Failed Breath Test in Colorado
Can I be arrested for DUI even if my BAC is under 0.08%?
Yes. Colorado allows DUI or DWAI charges based on observed impairment, regardless of BAC level.
What if I pass the breath test but fail field sobriety tests?
You can still be arrested. FST performance and other behavioral cues are used alongside chemical tests to determine impairment.
Is a breath test always required during a DUI stop?
Not always. While often requested, the officer may arrest based on other observations if the test is refused or not available.
Can prescription drugs lead to a DUI arrest?
Yes. If the medication impairs your ability to drive, you can be arrested — even if it was legally prescribed and no alcohol is involved.
What happens if I refuse to take the breath test?
Refusal can lead to automatic license suspension and may be used as evidence of impairment in a DUI case.
Does marijuana use trigger DUI charges in Colorado?
Yes. Even though marijuana is legal in the state, driving while impaired by it can result in DUI charges.
Is a DUI arrest the same as a conviction?
No. Arrest is the beginning of the process. Whether charges lead to conviction depends on evidence, testing, and court decisions.
Conclusion
Colorado law allows for DUI arrests based on much more than just a failed breath test. Drivers can — and often are — arrested based on a combination of field sobriety tests, observed behavior, and officer judgment. Refusing a breath test or registering a BAC under the legal limit doesn’t guarantee that you’ll avoid arrest if impairment is suspected.
Understanding how DUI arrests really work in Colorado helps dispel common myths. Breath tests are just one part of a broader system of enforcement. Whether alcohol, drugs, or a mix of both is involved, officers have the authority to act when a driver appears unable to safely control a vehicle.
For more information about how DUI arrests begin and what officers look for, read our What Triggers a DUI Arrest During a Traffic Stop resource. You can also learn how these situations fit into the larger DUI system on our How DUI Laws Work pillar page.